Neurocritical Care

, Volume 17, Supplement 1, pp 79–95

Emergency Neurological Life Support: Acute Non-Traumatic Weakness

Authors

    • Department of Intensive CareRoyal North Shore Hospital
  • Christine Bowles
    • Department of Emergency MedicineRoyal North Shore Hospital
  • Eelco Wijdicks
    • Department of NeurologyMayo Clinic Rochester
  • Scott D. Weingart
    • Division of ED Critical CareMount Sinai School of Medicine
  • Wade S. Smith
    • Department of NeurologyUniversity of California
Review Article

DOI: 10.1007/s12028-012-9752-7

Cite this article as:
Flower, O., Bowles, C., Wijdicks, E. et al. Neurocrit Care (2012) 17: 79. doi:10.1007/s12028-012-9752-7

Abstract

Acute non-traumatic weakness may be life-threatening if it involves respiratory muscles or is associated with dysautonomia. Most patients presenting with an acute muscle weakness have a worsening neurologic disorder that requires a rapid, systematic approach, and detailed neurologic localization of the findings. In many patients, urgent laboratory tests are needed and may involve neuroimaging. Because acute weakness is a common presenting sign of neurological emergencies, it was chosen as an Emergency Neurological Life Support protocol. An inclusive list of causes of acute weakness is explored, both by presenting complaint and anatomical location, with an outline of the key features of the history, examination, investigations, and treatment for each diagnosis.

Keywords

Neuromuscular failureHemiparesisTetraparesisNeurological examRespiratory failureENLS

Introduction

The differential diagnosis of acute non-traumatic weakness ranges from the imminently life-threatening to the trivial. The approach to this problem necessarily comprises synchronous resuscitation with investigations and management tailored to the individual patient.

Assessment of the airway is the initial priority. During resuscitation, consideration should be given to a several other time-critical diagnoses that require specific management. These are discussed in connection with tables that include the main features of the history, examination, investigations, and treatment for each diagnosis. Trauma is neither discussed here nor is weakness that is not acute in onset.

The ENLS suggested algorithm for the initial management of acute weakness is shown in Fig. 1. Suggested items to complete within the first hour of evaluating a patient with acute weakness are shown in Table 1.
https://static-content.springer.com/image/art%3A10.1007%2Fs12028-012-9752-7/MediaObjects/12028_2012_9752_Fig1_HTML.gif
Fig. 1

ENLS acute non-traumatic weakness protocol

Table 1

Acute weakness checklist for the first hour

□ Assess airway, breathing, and circulation

□ Characterize the weakness by detailed exam

□ Build an initial differential diagnosis of the causes of weakness

□ Consider emergency causes

□ Labs: glucose, electrolytes, Ca, Mg, PO4, BUN/Cr, LFTs, and coags

□ Special labs: TFTs, CK, ESR

□ Relevant imaging

Assessing Ventilation and the Need for Urgent Intubation

When breathing becomes compromised in patients with neurological weakness, the usual cause is collapse of the oropharyngeal muscles. Diaphragmatic weakness is another significant cause, the diaphragm being responsible for two thirds of respiratory effort. Poor gas exchange may also occur but is less common.

When there is uncertainty regarding the respiratory status and the direction of its trajectory, it is generally safer to intubate the patient prior to transport, if that is anticipated. If the airway is protected, and respiratory failure is due to the lower respiratory apparatus such as the intercostal muscles or the diaphragm, a trial of non-invasive ventilation may be considered—but not in a rapidly deteriorating patient (e.g., Guillain–Barré syndrome). Also, see the Airway, Ventilation, and Sedation protocol.

In the setting of acute weakness:
  • Consider oropharyngeal weakness, which increases the risk of aspiration and prevents clearance of secretions.

  • Consider pulmonary function tests to quantify neuromuscular respiratory insufficiency.

  • Continue to regularly assess the patient as his or her clinical condition may deteriorate rapidly.

Table 2 outlines factors to consider when deciding on whether to intubate. No single parameter independently predicts the need for intubation; rather, the constellation of signs and symptoms with a temporal trend should be considered. Certain salient points that are specific to intubation of patients presenting with weakness are listed in Table 3.
Table 2

Factors to consider in the decision to intubate [1, 2]

General

 Increasing generalized muscle weakness

 Dysphagia

 Dysphonia

 Dyspnea on exertion and at rest

Subjective

 Rapid shallow breathing

 Tachycardia

 Weak cough

 Interrupted speech (gasping for air)

 Use of accessory muscles

 Abdominal paradoxical breathing

 Orthopnea

 Weakness of trapezius and neck muscles: inability to lift head from bed

 Inability to perform single-breath count: count from 1 to 10 in single exhalation (roughly equal to FVC <1.0 L)

 Cough after swallowing

Objective

 Decreased level of consciousness (have a lower threshold to control the airway if patient requires transfer or movement to unmonitored areas)

 Hypoxemia

 Vital capacity <1 L or 20 mL/kg, or 50 % decrease in VC in a day

 Maximum inspiratory pressure >−30 cm H2O

 Maximum expiratory pressure <40 cm H2O

 Hypercarbia (a late finding)

Table 3

Special considerations for intubation [3]

Rapid sequence induction/intubation is advised

Avoid use of succinylcholine if there is evidence of underlying progressive neuromuscular disease (e.g., Guillain–Barre, chronic muscular weakness, or prolonged immobility). Consider 1.0–1.4 mg/kg rocuronium as an alternative [4]. Succinylcholine will be relatively ineffective to achieve muscle relaxation in myasthenia gravis. Either a higher dose (approximately 2.5 times standard dose) of succinylcholine can be used or half-dose of non-depolarizing agents (rocuronium 0.5–0.6 mg/kg)

Consider non-invasive ventilation as a temporizing measure in a neurologically stable patient with a neuromuscular condition expected to have rapid resolution (e.g., myasthenia gravis exacerbation)

Prepare atropine/glycopyrrolate, fluids, and vasopressors if there is evidence of autonomic instability

See the Airway, Ventilation, and Sedation protocol for additional information

Emergency Etiologies

In the initial assessment, a few conditions must be considered first. These are all time-critical emergencies that require resuscitation and rapid, safe neuroimaging to achieve a diagnosis and expedite treatment.

Acute ischemic stroke, typically presenting with hemiparesis or hemiplegia, is probably the most important emergency etiology to diagnose, since specific time-sensitive treatments are available. While it cannot be clinically discerned whether the acute stroke is ischemic or hemorrhagic, acute stroke teams (if available) should be notified immediately, or acute transfer to a primary or comprehensive stroke center should be considered if stroke treatments are not available locally. Rapid imaging and establishing the time of onset are imperative in gaging this urgency.

Acute onset of paraplegia or quadriplegia (tetraplegia) may indicate acute spinal cord compression, which is an emergency. Spinal cord compression may be traumatic or non-traumatic. Non-traumatic spinal cord injury may occur from compression (e.g., epidural abscess, hematoma, expanding tumor), spinal cord infarct, or acute demyelination. See Tables 6 and 7 for further details. Acute spinal cord injury may be the first manifestation of an underlying disorder (e.g., aortic dissection, acute leukemia) (Table 11).

In the acute phase, a flaccid paralysis below the level of traumatic spine injury is seen, and a sensory level will localize the involved segment. Certain cord injury syndromes have their own features. For example, acute cauda equina syndrome may present with lower limb weakness, prominent back pain, sciatica, perineal hypesthesia, bowel and bladder dysfunction, and decreased lower limb reflexes.

A postictal patient or a patient in status epilepticus can also present with weakness. Typically, there is little confusion about the diagnosis in a post-ictal patient. However, both post-ictal state and non-convulsive status epilepticus should be considered in the patient with acute weakness, particularly when a collateral history is not available.

In addition, acute generalized weakness may occur due to meningitis or encephalitis or an acute electrolyte disorder, most notably hypokalemia, hyperkalemia, or hypermagnesemia (Table 35). Marked hyperglycemia may present with an acute hemiplegia, but the majority of electrolyte disorders result in symmetric involvement. Hypoglycemia must be excluded early, but it should be noted that most of these patients are confused or have a decreased level of consciousness. Other causes that must be considered include magnesium and phosphate abnormalities.

Finally, specific drugs may cause acute weakness. For example, acute weakness may be caused by a lingering neuromuscular blocker administered during transport or intubation. Acute weakness is also a prominent feature of certain envenomations and organophosphate toxicity, though the latter is rare in the developed world (see Tables 9, 10).

Localization

To form a workable and realistic list of differential diagnoses, the etiology may be considered either in terms of the clinical presentation or by the anatomical location of the lesion.

Clinical Localization

Accurately defining the presenting complaint helps generate a focused differential diagnosis. A good clinical history is essential, as the examination may be difficult or unreliable in the obtunded or confused patient. However, it should be possible to elicit whether the deficit is unilateral or bilateral, which anatomical region is affected, and whether there is a sensory deficit.

With a cooperative patient, it should also be possible to establish whether the deficit is symmetrical or asymmetrical, and proximal or distal. Note that it is important to attempt to differentiate between upper motor neuron (UMN) and lower motor neuron (LMN) lesions in the acute setting, though this may be difficult in some situations. In well-established UMN lesions, hyperreflexia (brain and spinal cord), increased tone, and a positive Babinski sign are seen. In comparison, LMN lesions (from the anterior horn cells to the muscles) cause a flaccid, arcflexic weakness and, with time, atrophy and fasciculations. However, in the acute phase, UMN lesions may mimic a LMN lesion: flaccid paralysis, normal or reduced tone, and unreliable reflexes. There is often not enough time for atrophy to be evident, and fasciculations are rarely seen.

Hemiparesis

  • Acute stroke: ischemic, hemorrhagic, or subarachnoid hemorrhage

  • Intracranial mass (Table 18)

  • Meningitis/encephalitis

  • Hypoglycemia/hyperglycemia (Tables 8, 16)

  • Postictal Todd’s paresis (Table 17)

  • Hemiplegic migraine (Table 15)

  • Brown–Séquard syndrome (Table 19)

Hemiparesis is acute weakness involving only one side of the body. While acute hemiplegia is most commonly due to an ischemic stroke, other differentials must be considered, as management of these differentials vary.

The history and demographic of the patient is likely to narrow the diagnosis, and examination findings provide further clues. A blood glucose level and a non-contrast head computed tomography are part of the initial workup.

Quadriparesis/Paraparesis ± Sensory Level

  • Spinal cord compression

  • Spinal cord infarction (Table 6)

  • Transverse myelitis (Table 7)

Quadriparesis/paraparesis is symmetrical weakness of either all four limbs (quadriparesis) or legs (paraparesis), characteristically with a sensory level. Non-traumatic spinal cord injury may occur from compression (e.g., epidural abscess, hematoma, expanding tumor, prolapsed intervertebral disc), ischemia, or inflammation (transverse myelitis).

In the acute phase, a flaccid paralysis below the level of cord injury is typically seen, with an accompanying corresponding sensory level, although there is considerable variation. Neurologic examination should localize the lesion in patients with acute paraplegia or quadriplegia. Sensory abnormalities localize in the vertical plane (cervical, lumbar, or sacral) and, when combined with other long tract signs, point to localization in the horizontal plane (extradural, intradural, or intramedullary). Key sensory levels (T4 nipple, T10 navel) should be used. Spinal cord infarction and transverse myelitis may cause acute cord injury without cord compression; these are outlined in the Tables 6 and 7.

Proximal Weakness

  • Acute myopathy (Table 28)

  • Guillain–Barré syndrome (Table 21)

  • Acute diabetic lumbosacral radiculoplexus neuropathy (DLRN) (Table 30)

  • Myasthenia gravis (Table 13)

  • Acute West Nile virus associated paralysis

  • Lambert–Eaton myasthenic syndrome (LEMS) (Table 29)

Proximal weakness is weakness predominantly affecting the hip or shoulder girdle musculature. Acute proximal weakness classically presents with difficulty rising from a chair or brushing hair. The most common cause is myopathy. Less common causes include LEMS (Table 29) and myasthenia gravis. DLRN may be the presenting feature of diabetes mellitus and is also important to consider. While poliomyelitis is very rare in western countries, it remains endemic elsewhere (Table 34). West Nile virus, with similar semiology as acute poliomyelitis, is more common in the United States and Europe.

Distal Weakness

  • Vasculitic neuropathy (Table 31)

  • Toxin induced peripheral neuropathy (Table 32)

  • Nerve compression syndromes (Table 33)

Distal weakness is weakness mainly affecting the extremities. It is typically caused by peripheral neuropathies that often present along with sensory symptoms. Distal weakness affects the hands and feet, causing the patient to drop objects or develop gait disturbance due to foot drop. The pattern of weakness and history are of great significance.

Of the many types of peripheral neuropathy, vasculitic and toxin induced are the most likely to produce an acute weakness. It may also be produced by local nerve compression syndromes (e.g., carpal tunnel syndrome that predominantly affects peripheries, causing both sensory and motor symptoms).

Monoparesis

  • Acute stroke

  • Intracranial mass (Table 18)

  • Postictal Todd’s paresis (Table 17)

  • Nerve compression syndromes (Table 33)

  • Diabetic lumbosacral radiculoplexus neuropathy (Table 30)

  • Acute poliomyelitis (Table 34)

Monoparesis refers to paralysis of a single muscle, muscle group, or limb. Acute paralysis involving a single limb may be caused by a central or a peripheral lesion. Historical and examination factors may help to localize the lesion. For example, sudden onset right arm weakness with an associated dysphasia is most likely to result from a central lesion, whereas wrist drop in the right hand, with hypoesthesia on the back of the hand following falling asleep with the arm over the back of a chair, results from a peripheral nerve compression syndrome. Poliomyelitis is rare, but can occur in the unvaccinated.

Significant Associated Findings

Certain constellations of symptoms and signs can make specific, often unusual diagnoses more likely. Table 4 lists some of these, and each is elaborated further in separate tables. Stroke syndromes may also have characteristic patterns which are too numerous and varied to discuss here. However, findings such as aphasia, agnosia, apraxia, and neglect with acute weakness or sensory signs should prompt consideration of acute stroke.
Table 4

Significant associated findings

Associated findings

Diagnosis to consider

Acute tetraplegia, facial muscles paralyzed except eyes, clear sensorium

Locked-in syndrome (also consider residual neuromuscular blockade) (Table 20)

Fatigable weakness in eyelids and extra-ocular muscles with variable weakness elsewhere and no sensory symptoms

Myasthenia gravis (Table 13)

History of animal bite, descending paralysis, and possible coagulopathy, rhabdomyolysis, and shock

Envenomation (Table 10)

Severe, refractory hypertension with headache and transient, migratory neurological non-focal deficits

Hypertensive encephalopathy (Table 12)

Ascending paralysis following upper respiratory mild viral illness/infection

Guillain–Barre syndrome (Table 21)

Descending symmetrical paralysis with a clear sensorium and no fever

Botulism (Table 22)

Weakness with prominent cholinergic signs and symptoms

Organophosphate toxicity (Table 9)

Heavy metal exposure, prominent gastrointestinal symptoms, then multi-organ failure

Heavy metal toxicity (Table 23)

Episodic proximal weakness with family history

Periodic paralysis (Table 24)

Heliotrope rash with proximal weakness

Dermatomyositis (Table 25)

Abdominal pain, proximal weakness, psychiatric symptoms, red urine

Acute intermittent porphyria (Table 26)

Tick bite followed by ascending paralysis

Tick paralysis (Table 27)

Not Neuromuscular

Some disease states may produce symptoms of generalized weakness or fatigue that do not have a neuromuscular basis. These may be medical emergencies in their own right meriting urgent specific treatment (see Table 14).

Anatomical Localization

Understanding the cause of weakness can be aided by localizing anatomically, since diseases are often specific for each anatomic region. The neurological examination greatly aids the localization of weakness by anatomic means. Figure 1 breaks down anatomic regions into the brain and spinal cord, the anterior horn cell, the peripheral nerve, neuromuscular junction (NMJ), and muscle.

Diseases of the brain and spinal cord produce “UMN weakness,” meaning disruption of descending motor axons or cell bodies that innervate the LMN (the anterior horn cell, peripheral nerve, and NMJ). After performing a neurological examination, refer to Table 5 to ascribe the appropriate anatomic localization.
Table 5

Physical exam findings for each anatomic localization of weakness

Localization

Pattern of weakness

Sensory loss

Reflexes

Acute etiologies

Cerebral cortex, brainstem, or spinal cord

Distal > proximal, extensors > flexors, hemiparesis or single limb

May be present depending on whether sensory tracts or cortex are involved

Elevated however, reflexes may be decreased initially but later increase

Acute stroke, subarachnoidhemorrhage, seizure, hypertensive encephalopathy

Spinal cord

Distal > proximal, extensors > flexors, paraparesis, quadriparesis, rarely hemiparesis

May be present depending on whether sensory tracts are involved; loss of sensation below a certain spinal level is diagnostic

Elevated however, reflexes may be decreased initially initially but later increase

Epidural abscess, tumor, spinal cord infarct

Anterior horn cell

Proximal and distal, fasciculations are prominent

Absent

Decreased if muscle bulk is severely decreased; increased in ALS

ALS, polio

Peripheral nerve

In the distribution of the nerve, or diffusely present as stocking/glove weakness

Present

Decreased

Guillain–Barre syndrome, vasculitis

Neuromuscular junction

First in eye muscles, neck extensors, pharynx, diaphragm, followed by more generalized weakness

Absent

Normal, decreased if muscle is paralyzed

Botulism, tick bite, organophosphate

Muscle

Proximal

Absent

Normal unless muscle severely weak

Rhabdomyolysis

The key features to focus on are the presence or the absence of sensory signs (loss of sensory modality) or symptoms (complaints of numbness or tingling). If sensory signs/symptoms are absent, peripheral nerve is eliminated, and central nervous system processes are reduced in likelihood.

Anterior horn cell causes are principally Lou–Gehrig’s disease (ALS) and polio, neither of which have acute treatments. Reflexes are helpful to determine among the remaining causes which is most likely to occur. In general, lesions of the brain and spinal cord and the NMJ are the most emergent causes to consider, as there are specific treatments for some of these diseases (acute stroke and spinal cord compression) or public health concerns (botulism, Table 22).

Ideally, both the anatomic and the clinical localizations will agree with each other and the diagnosis can then be made. Substantial disagreement in localizations should raise concerns over one or both localizations.
Table 6

Spinal cord infarction [5]

History

 Acute tetraparesis or paraparesis with a sensory level corresponding with level of cord infarct

 No historical suspicion of trauma or infection

 60 % of patients present with pain that localizes to the level of injury

 May be associated with aortic surgery or procedures such as celiac ganglion ablation

 Risk factors: female sex, atrial fibrillation with no anticoagulation, hypertension, hypercholesterolemia, type II diabetes, smoking, hypercoagulable states

Examination

 Anterior spinal artery syndrome is most common: loss of motor function and pain/temperature sensation, with relative sparing of proprioception and vibratory sense below the level of lesion

 Initially presents with a flaccid paralysis and loss of deep tendon reflexes

 Usually bilateral weakness, occasionally unilateral

 Posterior spinal artery syndrome: loss of proprioception and vibratory sense below the level of the injury and total anesthesia at the level of injury; weakness usually mild/transient

 Other variants possible

Investigations

 MRI is diagnostic, showing an ischemic lesion defined as a well-demarcated T2-weighted hyperintensity matching an arterial territory of the cord

 Spinal angiogram recommended if vascular malformation suggested from MRI

 Other investigations are as for ischemic stroke, i.e., pro-thrombotic and vasculitis screen, toxicology screen, echocardiography, duplex ultrasonography of the cervical arteries, chest X-ray, electrocardiography, 24-h Holter electrocardiography

Treatment

 Supportive treatment only

 Corticosteroids are currently not recommended, as the current literature indicates minimal benefits outweighed by the risks of this treatment

 Consider anti-platelet agents in patients with underlying vascular risk factors or co-morbid vascular disease to prevent more secondary atherothrombotic events

Table 7

Transverse myelitis [6]

History

 The development of isolated spinal cord dysfunction over hours or days in patients in whom there is no evidence of a compressive lesion

 Segmental spinal cord injury caused by acute inflammation, usually thoracic cord

 50 % have preceding infection, often viral

 Can occur in multiple sclerosis

 Symptoms usually develop over hours

 Present with weakness and sensory disturbance below the level of the lesion

 Back pain with bladder and bowel dysfunction is common

Examination

 Evidence of myelopathy, with weakness and sensory symptoms that correspond to a specific dermatomal and myotomal level

 Increased or decreased sensation with paresthesia may be present

Investigations

 MRI is diagnostic; however, negative MRI does not exclude diagnosis

Treatment

 Many patients are treated with IV methylprednisolone, IVIG, or plasma exchange

Table 8

Hypoglycemia (BGL < 3 mmol/L) [7]

History

 Diabetes

 Insulin regimen

 Oral hypoglycemics

 Alcohol

 Sepsis

 Liver disease

 Any cause of hypocortisolemia

Examination

 Generalized non-specific weakness

 Many forms of focal neurological deficit possible, which may mimic stroke

 Tremor, palpitations, anxiety, sweating, hunger, and paresthesia

 Dysphoria

 Seizures

 Decreased consciousness

Investigations

 Blood glucose level (more accurate from venous or arterial blood rather than capillary and measured in a blood gas analyzer)

 CT head

Treatment

 20 mL IV 50 % dextrose

 Repeat if necessary

 Oral carbohydrate if patient safe to swallow

 Alternatively, 1 mg glucagon IM or IV

Table 9

Organophosphate toxicity [8, 9]

History

 Insecticide exposure (e.g., malathion, parathion, diazinon, fenthion, dichlorvos, chlorpyrifos, ethion)

 Nerve gas exposure (e.g., sarin, VX, soman, tabun)

 Ophthalmic agents (e.g., echothiophate, isoflurophate)

 Anti-helminthics (trichlorfon)

Examination

 Fasciculations with paralysis

 Bronchospasm, bradycardia, miosis, lacrimation, salivation, bronchorrhea, urination, emesis, and diarrhea

 At 48–72 h, neck flexion weakness, decreased deep tendon reflexes, cranial nerve abnormalities, proximal muscle weakness, and respiratory insufficiency may develop

 At 1–3 weeks, ascending flaccid paralysis may develop (delayed neuropathy)

Investigations

 RBC acetyl cholinesterase (if available) for severity and to guide oxime therapy

Treatment [9]

 Remove contaminated clothes

 100 % oxygen

 Intubation (no succinylcholine)

 Atropine 1.2 mg IV stat, then double the dose every 5 min until bronchospasm and secretions are controlled; an infusion may be required, and glycopyrrolate is an alternative

 Pralidoxime 2 g IV over 15 min, then as an infusion

 Diazepam to prevent seizures

Table 10

Envenomation [10, 11]

History

 Snake bite [11]

 Scorpion sting (C. exilicauda and C. suffusus)

 Marine envenomation (mainly Australia):

  Stonefish

  Blue-ringed octopus

  Ingestion of puffer fish (prepared as delicacy in Japan: fugu)

Examination

 Snake bites [11]

  Cardiovascular: hypotension, shock, arrest

  Neurological: paralysis-ptosis, diplopia, bulbar palsy, dysarthria; progression to respiratory muscle paralysis; desaturation is a late sign

  Coagulopathy: decreased GCS due to intracranial hemorrhage, bleeding from bite site, ecchymoses, bleeding gums, hemarthroses

  Rhabdomyolysis: tender muscles

  Bite site: bleeding and necrosis; do not remove the pressure immobilization bandage to examine the bite site

 Scorpion sting

  Cranial nerve and somatic skeletal neuromuscular dysfunction, with pain and paresthesia

 Blue-ringed octopus and puffer fish envenomation

  Descending symmetrical flaccid paralysis with clear sensorium, nausea and vomiting, blurred vision, ataxia, respiratory failure; symptoms delayed if ingested

 Stonefish envenomation

  Weakness in the affected limb, severe pain, shock

Investigations

 All envenomations: serial pulmonary function tests if descending paralysis; other investigations as clinically indicated

 Snake bite: FBC, EUC, LFTs, CK, whole blood clotting time, coagulation screen, D-dimer, fibrinogen levels, urinalysis for blood (myoglobin), head CT if decreased GCS; if envenomation suspected on the basis of clinical findings and pathology, use venom detection kit for bite swab and urine to determine appropriate anti-venom

Treatment

 Pressure immobilization bandage

 Anti-venom, preferably specific

 Supportive care with early intubation for paralysis

Table 11

Aortic dissection [1214]

History

 Severe, sharp or “tearing” posterior chest or back pain

 Anterior chest pain

 Chest pain may be associated with an acute neurological deficit

 Neurological features may include hemiplegia, monoplegia, and paraplegia

 History of hypertension is common

Examination

 One-third experience neurological deficits [13]

 May present with only neurological manifestations in 10 % of Type A dissections

 Acute aortic regurgitation may be present (31.6 %) [12]

 Weak or absent pulse (15.1 %) (carotid, brachial, or femoral) [12]

 Other features may include acute myocardial infarction, cardiac tamponade, hemothorax, hypotension, pain, abdominal pain, back or flank pain, renal failure, or Horner’s syndrome

 If hypotensive, look for evidence of tamponade, cardiogenic shock, and blood loss

Investigations

 FBC, group, and save

 ECG to exclude myocardial infarction (may be associated if coronary arteries occluded)

 CXR for widened mediastinum and hemothorax

 Bedside transesophageal echocardiogram (transthoracic if transesophageal not available)

 CT aortogram

 CT head

Treatment

 Reduce systolic BP to 100–120 mmHg and heart rate to 60–80 bpm with an IV beta-blocker; consider a nitroprusside infusion; avoid hydralazine

 Type A: urgent surgery

 Type B: initial medical management, though 20 % still require surgery; consider surgery if patient demonstrates progression of dissection, intractable pain, organ malperfusion, or extra-aortic blood

Table 12

Hypertensive encephalopathy [15, 16]

History

 Long standing, poorly controlled hypertension

 Drug history and poor compliance with anti-hypertensives, especially clonidine

 Headaches, confusion, visual disturbances, nausea, and vomiting

 Symptoms from other end-organ damage

Examination

 Severe, sustained hypertension, with a diastolic BP that is usually >130 mmHg

 Transient, migratory neurological non-focal deficits, ranging from nystagmus to weakness, and an altered mental status, ranging from confusion to coma

 Fundoscopy may reveal grade IV retinal changes including papilledema, hemorrhage, exudates, and cotton wool spots

 Cardiovascular exam findings consistent with severe chronic hypertension

 Other causes of weakness, including hemorrhagic stroke, are excluded

Investigations

 FBC (microangiopathic hemolytic anemia)

 Urea and creatinine, urinalysis (hypertensive nephropathy)

 Urine toxicology screen

 CT head

Treatment

 Invasive BP monitoring

 Use a continuous infusion of an IV anti-hypertensive (e.g., sodium nitroprusside, beta-blocker, or calcium channel antagonist)

 Lower the diastolic pressure to 100–110 mmHg within 6 h

 Aim to reduce initial MAP by no more than 25 %

 Avoid lowering BP too much, too quickly, as it may lead to cerebral ischemia

Table 13

Myasthenia gravis [17, 18]

History

 History of myasthenia gravis (but may have not been diagnosed)

 Acute decompensation may be spontaneous or precipitated by infection, surgery, or tapering of immunosuppression

 Drugs may precipitate symptoms, including certain antibiotics, beta-blockers, and magnesium

 Excessive treatment with cholinesterase inhibitors may paradoxically cause weakness (see Table 9)

 A myasthenic crisis refers specifically to respiratory failure due to acquired autoimmune myasthenia gravis

Examination

 85 % of patients have involvement of the eyelids and extra-ocular muscles, resulting in ptosis and/or diplopia [18]

 Weak, flaccid facial muscles

 Nasal speech with impaired bulbar reflexes

 Neck and proximal limb weakness may occur

 Respiratory failure occurs in 1 %

 Respiratory exam may reveal evidence of aspirated secretions or infection

Investigations [18]

 Ice pack test (e.g., ice on affected eyelid improves ptosis)

 ACh receptor antibody if diagnosis uncertain

 Pulmonary function tests

 Consider arterial blood gas

 Consider CT chest (thymoma may affect breathing)

Treatment

 For acute decompensation, admit to ICU

 Frequent forced vital capacity measurement

 If intubated, withdraw anticholinesterase medications

 Plasmapheresis or IV immunoglobulin

 High-dose steroids (e.g., 80 mg prednisolone)

 Consider other immunosuppressants

Table 14

Non-neuromuscular pathology

Consider

 Any severe medical illness can have weakness as a symptom, but generally these will become clinically obvious during the patient’s evaluation

 Diagnoses of exclusion

  Malingering

  Conversion disorder

  Chronic fatigue syndrome

  Anxiety disorders

  Fibromyalgia

Table 15

Hemiplegic migraine [19, 20]

History [19]

 Typical hemiplegic migraine attacks start in the first or second decade of life and include gradually progressing visual, sensory, motor, aphasic, and often basilar-type symptoms, accompanied by headaches

 Most patients also have attacks of migraine with typical aura without weakness

 Aura consists of a fully reversible motor weakness

 The weakness may resolve before the headache starts or may persist for days

 May be preceded by a prodrome of affective symptoms 24–48 h prior to the migraine

 May be accompanied by ipsilateral numbness or tingling, with or without a speech disturbance

 In familial hemiplegic migraine (FHM), at least one first or second degree relative has had similar episodes

 Sporadic hemiplegic migraine is diagnosed when no first or second degree relative has had attacks of hemiplegic migraine

Examination

 Neurological exam assessing for other causes of hemiplegia

 The short time course and full reversibility of deficit are key components

Investigations

 Diagnosis of exclusion

 CT or MRI to exclude other etiologies

 SPECT scan may show hypoperfusion during the aura phase

 Genetic testing is available for FHM

Treatment

 Early neurologist involvement

 Anti-emetics, non-steroidal anti-inflammatory drugs, and non-narcotic pain relievers

 Triptans and ergotamine preparations are contraindicated because of their potential vasoconstrictive effects

 There is no evidence for anti-platelet agents

 Prophylactic treatment may include lamotrigine and acetazolamide

Table 16

Hyperglycemia [21, 22]

History

 History of diabetes

 Possible precipitating events (e.g., infection, myocardial infarction, surgery, critical illness)

 Diabetic regimen and compliance

 Neurological symptoms primarily occur when plasma osmolality is >320 mOsmol/L

 Neurological symptoms may include hemiparesis, focal motor deficits, decreased consciousness, and seizures

 Diabetic ketoacidosis (DKA) usually evolves rapidly, over a 24-h period

 Symptoms of hyperosmolar hyperglycemia syndrome (HHS) develop gradually with polyuria, polydipsia, and weight loss for several days before presentation

Examination

 Level of consciousness may be reduced

 Detailed neurological exam may reveal focal motor and sensory deficits including aphasia, hyperreflexia, hemianopia, and brainstem dysfunction

 Other findings associated with HHS include evidence of volume depletion

 Patients with DKA may present with hyperventilation and abdominal pain

Investigations

 Serum glucose

 Plasma osmolality

 Serum electrolytes (with anion gap), urea, and creatinine

 Complete blood count with differential

 Urinalysis, and urine ketones by dipstick

 Serum ketones (if urine ketones are present)

 Blood gas (if urine ketones or anion gap are present)

 Electrocardiogram

 CT head to exclude other causes

Treatment

 Fluid replacement to correct hypervolemia and hyperosmolality

 Insulin infusion

 Close electrolyte monitoring with potassium, magnesium, and phosphate replacement

 Treat precipitant (e.g., sepsis)

Table 17

Postictal Todd’s paresis [23, 24]

History

 Follows seizure

 More common when seizures prolonged (status epilepticus)

 Can last seconds, but often has a duration of hours

Examination

 Weakness always present, but wide variation in location, severity, duration, tone reflexes, and sensory involvement

Investigations

 To exclude other forms of weakness

Treatment

 Supportive

Table 18

Intracranial mass [25, 26]

History

 Hemiparesis is uncommon with brain tumors

 Other symptoms of brain tumors vary widely from headaches, seizures, nausea, ataxia, and cognitive dysfunction to focal neurological deficits

 Manifestations may be subtle, particularly in the early stages

 As with other UMN lesions, weakness is generally more pronounced in flexors of lower extremities than in extensors, and more pronounced in extensors than flexors in upper extremities

 Transient weakness may represent a postictal state, as in postictal Todd’s paresis

 Fever, headache, and focal neurological deficit is characteristic of a brain abscess

Examination

 Detailed neurological exam may help localize the lesion and create a list of differential diagnoses

Investigations

 CT head with and without contrast to identify tumor, exclude other diagnoses, look for associated hemorrhage, and assess for bone or vascular involvement

 MRI usually required

 Consider functional MRI, perfusion MRI, PET, and SPECT imaging, depending on the situation

Treatment

 Involve neurological clinicians

 Peritumoral vasogenic edema responds to glucocorticoids (dexamethasone IV 10 mg stat then 4 mg IV every 6 h)

 Corticosteroid use should be avoided prior to biopsy or surgery if either a primary CNS lymphoma or infectious process is part of the differential diagnosis

 Manage raised ICP in the standard step-wise approach

 If there is evidence of intra-tumoral hemorrhage, correct any coagulopathy and control BP

 Brain abscesses require targeted anti-microbial treatment and sometimes drainage

Table 19

Brown–Séquard syndrome [27, 28]

History

 Sudden onset hemiplegia with contralateral loss of pain and temperature

 Non-traumatic causes include

  Extramedullary spinal neoplasm

  Herniated cervical intervertebral disc

 Incomplete hemisection causing Brown-Sequard syndrome plus other signs and symptoms is more common than the classical form

Examination

 Ipsilateral weakness

 Impaired ipsilateral proprioception and vibratory sensation

 Contralateral loss of pain and temperature sensation

Investigations

 MRI

 CT myelography if MRI contraindicated

Treatment

 Spinal precautions if from traumatic injury

 Surgery with spinal cord decompression

 See Spinal Cord Compression and Traumatic Spinal Injury Protocols

Table 20

Locked-in syndrome [29, 30]

History

 Sudden onset tetraplegia, facial weakness, and frequently loss of horizontal gaze

 Most commonly caused by ischemic stroke

 May be caused by central pontine myelinolysis, encephalitis, or tumor

Examination

 Flaccid symmetrical tetraparesis

 Consciousness preserved, with voluntary vertical eye and eyelid movements possible

 Hearing, vision, pupillary reflexes, and sensation all normal

 Consciousness may be affected initially but returns to normal

Investigations

 CT brain with spiral CT angiography [30]

 Consider MRI/MRA

Treatment

 See Acute Stroke protocol

Table 21

Guillain–Barré syndrome [3136]

History [34]

 Usually follows 2–4 weeks after mild respiratory or gastrointestinal illness

 Typically symmetrical ascending paralysis

 10 % present with upper limb or facial weakness

 Respiratory failure occurs in approximately 10 % and oculomotor weakness in 15 %

 Limb paresthesia are common (80 %)

 Dysautonomia occurs in 70 %

Examination [34]

 Symmetrical ascending paralysis

 Absent deep tendon reflexes

 Signs of respiratory failure (see Table 3)

 Miller Fisher syndrome variant presents with ophthalmoplegia, ataxia, and areflexia

 In acute motor axonal neuropathy variant, sensation is preserved and occasionally deep tendon reflexes

 Acute motor and sensory axonal neuropathy has more sensory symptoms

 Other rarer variants exist [35]

Investigations

 CSF analysis: elevated protein, normal cell count

 Electromyography

 Nerve conduction studies

 Glycolipid antibodies may be associated with different subtypes

Treatment

 Supportive care

 Plasma exchange and IVIG are equivalent in efficacy, and both improve outcome. Choice depends on local availability, patient preference, risk factors, and contraindications

 No benefit for corticosteroids [36]

Table 22

Botulism [3739]

History

 Descending symmetrical paralysis with a clear sensorium and no fever

 No sensory deficits other than blurred vision

 If foodborne, follows ingestion by 12–36 h

 Prodromal symptoms include nausea, vomiting, abdominal pain, diarrhea, and dry mouth with sore throat [37]

 Wound botulism may follow deep infected regions with the presence of spores

 Infantile botulism occurs from 1 week to 1 year in infants who are formula fed and may present with constipation followed by weakness, feeding difficulties, descending or global hypotonia, drooling, anorexia, irritability, and weak cry [38]

Examination

 Cranial nerves first affected: fixed dilated pupils (causing blurred vision), diplopia, nystagmus, ptosis, dysphagia, dysarthria, and facial weakness

 Flaccid paralysis descends and commonly involves muscles of respiration and may cause bladder and bowel dysfunction

Investigations

 Do not delay treatment waiting for tests

 Stool, vomit, suspected food and wound cultures looking for C

 Botulinum spores serum assay for botulinum toxin

 Pulmonary function tests

Treatment [39]

 Equine serum heptavalent botulism antitoxin used for children >1 year of age and adults

 Human-derived botulism immune globulin used for infants <1 year of age

·Penicillin G (or metronidazole) for wound botulism but not for other forms

Table 23

Heavy metal toxicity [4042]

History

 Peripheral neuropathies may occur within a few hours to days of acute high-dose exposure, especially lead, arsenic, and thallium [42]

 Metal toxicities most commonly present with nausea, persistent vomiting, diarrhea, and abdominal pain and often with encephalopathy, cardiomyopathy, dysrhythmias, acute kidney injury, and metabolic acidosis

Examination

 Detailed CNS and PNS exam

 Lead neuropathy initially affects motor fibers in radial and peroneal distributions

 Mees lines (horizontal hypopigmented lines across all nails)

 Evidence of anemia and renal or liver failure

Investigations

 FBC (anemia) with blood film analysis (looking for basophilic stippling, which is found in lead toxicity or arsenic toxicity but is not specific)

 Urea, creatinine, electrolytes, and liver function tests and coagulation studies assessing for renal or liver failure

 Serum and urine metal levels (specifically, depending on which metal suspected)

Treatment

 Stop further exposure

 Consult toxicologist/poison center

 Consider polyethylene glycol whole bowel irrigation

 Consider chelation therapy in lead intoxication with encephalopathy (e.g., succimer, dimercaprol)

Table 24

Periodic paralysis (PP) [43]

History

 Episodes of flaccid muscle weakness occurring at irregular intervals with normal strength between episodes

 Usually hereditary, therefore family history is important

 Various types of periodic paralysis exist, including

  Hyperkalemic PP

  Hypokalemic PP

  Paramyotonia congenita

  Thyrotoxic PP

  Andersen–Tawil syndrome

 Seek precipitants (e.g., post exercise, fasting, cold alcohol, stress, and duration of episode)

Examination

 All forms usually exhibit

  Interictal lid lag and eyelid myotonia

  Normal sensation

  Fixed proximal weakness

  Diminished reflexes during episode

 Differentiating findings include perioral and limb paresthesias, myotonia between attacks, pseudo-hypertrophy of muscles, and findings of thyrotoxicosis

Investigations

 Serum potassium (although not always low in “hypokalemic” PP)

 Elevated creatine kinase

 Potassium: creatinine ratio

 Blood gas analysis for evidence of concomitant metabolic acidosis or alkalosis

 ECG

 Consider EMG and nerve conduction studies

Treatment

 Hyperkalemic PP (milder) usually responds to high carbohydrate food; thiazide or acetazolamide for prophylaxis

 For hypokalemic PP (more severe weakness), potassium supplementation (e.g., 40–60 mmol KCl orally, IV if severe weakness); acetazolamide for prophylaxis

 Paramyotonia congenita: weakness mild, no specific treatment

 Thyrotoxic PP: beta-blockers; treat thyrotoxicosis

 Andersen–Tawil syndrome: acetazolamide as prophylaxis for PP

Table 25

Dermatomyositis [44]

History

 May present with skin and/or muscle involvement

 Proximal muscle weakness: muscle fatigue or weakness when climbing stairs, walking, rising from a sitting position, combing hair, or reaching for items above shoulders

 Characteristic rash

 Systemic symptoms include arthralgia, arthritis, dyspnea, dysphagia, arrhythmia, and dysphonia

Examination

 Heliotrope rash (blue-purple discoloration on the upper eyelids)

 Raised, violaceous, scaly eruption on the knuckles (Gottron’s papules)

 Proximal symmetrical muscle weakness

 Muscle pain and tenderness may be present

 Sensation is normal, and tendon reflexes are preserved

 Joint swelling (particularly of the hand) occasionally occurs in some patients with dermatomyositis

 May be signs of underlying malignancy (present in 20–25 %)

Investigations

 Elevated CK, aldolase, lactate dehydrogenase, or alanine aminotransferase

 Auto-antibody serology not useful for acute diagnosis

 Skin biopsy

 Muscle biopsy: inflammation, perifascicular atrophy

Treatment

 Corticosteroids: prednisone (0.5–2 mg/kg/day) up to a dose of 60 mg/day initially

 Consider immunosuppressive or cytotoxic steroid sparing agents

 Consider IVIG if refractory

Table 26

Acute porphyria [45]

History

 Rare disorder presenting with abdominal pain and psychiatric symptoms

 Pain may begin in chest or back and move to abdomen

 Gastrointestinal symptoms are common (e.g., vomiting, diarrhea, constipation)

 Acute weakness may occur early or late

 Seizures possible

 Use of certain medications known to exacerbate

Examination

 Muscle weakness usually begins proximally and more often in upper limbs

 Symmetrical hypotonic, hyporeflexic flaccid paralysis

 Up to 20 % suffer respiratory muscle paralysis

 No rash unlike other forms of porphyria

 Tachycardia and hypertension may be present

Investigations

 Sodium: hyponatremia

 Urine color: dark/reddish

 Urine analysis: increased porphobilinogen

Treatment

 IV hemin

 Manage hyponatremia appropriately

 Consider anti-epileptic drugs

 Supportive management

Table 27

Tick paralysis [46, 47]

History

 Typically presents with unsteady gait followed by an ascending symmetrical flaccid paralysis 2–6 days post-tick attachment

 Sensory symptoms include paresthesias and hypoesthesia in limbs and face

 Anorexia, lethargy, drowsiness, and confusion may precede weakness

 Ataxia may be only symptom

Examination

 Tick found attached to patient

 Ascending symmetrical flaccid paralysis

 Hypotonic, hyporeflexic

 Progresses to affect all cranial nerves including pupillary dilatation

 Potential respiratory muscle compromise

 Sensory function is generally preserved other than mild paresthesias and hypoesthesis

 No fever

Investigations

 Locate tick

 EMG shows reduced amplitude of compound muscle action potentials

 No abnormalities seen with repetitive nerve stimulation studies

 Labs, CSF analysis, MRI all typically normal

Treatment

 Paralyze tick with insecticide and remove with forceps

 Supportive care

Table 28

Acute myopathy [43, 48]

History

 Metabolic causes: periodic paralyses, hypo and hyperkalemia, hypophosphatemia (Table 36)

 Inflammatory causes: polymyositis, dermatomyositis, rhabdomyolysis, infectious causes

 Toxic etiologies: alcohol, corticosteroids, statins, retroviral agents, colchicine, cocaine, heroin

 Endocrine causes: Addison’s disease, Cushing’s disease, hypo or hyperthyroidism, hyperparathyroidism

 Typically presents with symmetric proximal muscle weakness, malaise, and fatigue

 No sensory complaints except occasional myalgia

 In rhabdomyolysis, dark colored urine and/or fever may be present

Examination

 Symmetric proximal muscle weakness

 No sensory disturbance other than myalgia

 Dark urine in rhabdomyolysis

 Fever may be present in rhabdomyolysis, polymyositis, and infectious causes

 Other findings specifically associated with associated endocrinopathies may be present

Investigations

 CK with isoenzymes (may not correlate with clinical condition)

 Electrolytes, calcium, magnesium

 Serum urea, creatinine, and electrolytes

 Complete blood count

 Erythrocyte sedimentation rate

 Aspartate aminotransferase

 Urinalysis: myoglobinuria

 Specific workup for individual endocrinopathies

 Consider EMG, nerve conduction velocity testing, and muscle biopsy

Treatment

 Remove or treat any precipitant

 Safely correct electrolyte abnormalities

 Vigorous hydration for rhabdomyolysis

Table 29

Lambert–Eaton myasthenic syndrome (LEMS) [4850]

History

 In 40 % of patients with LEMS, cancer (commonly small cell lung cancer) is present

 Progressive proximal lower limb weakness (e.g., difficulty standing from sitting)

 Ptosis, diplopia, and dysarthria as cranial nerves become involved, (less commonly than in myasthenia gravis)

 Autonomic dysfunction with dry mouth

 Exacerbated by heat or fever and certain drugs

Examination [49]

 Proximal muscle weakness, lower limbs more than upper

 Depressed tendon reflexes, post-tetanic potentiation, and autonomic changes

 Sensation preserved

 Ptosis or diplopia (usually mild) in 25 %

 Respiratory failure rare

Investigations

 Voltage gated calcium channel antibodies

 AChR antibodies

 Repetitive nerve stimulation: characteristic findings

 EMG: characteristic findings

 Look for malignancy with imaging, consider bronchoscopy

Treatment [50]

 Confirm diagnosis and distinguish from myasthenia gravis before starting treatment

 Supportive treatment in interim

 Treat underlying malignancy if it is found

 When confirmed, consider 3,4-diaminopyridine, IVIG, or plasma exchange

Table 30

Diabetic lumbosacral radiculoplexus neuropathy [51, 52]

History

 Diabetes mellitus with proximal weakness in the quadriceps, hip adductors, and iliopsoas muscles

 Asymmetrical pain in the hip, buttock, or thigh

 Often occurs in conjunction with significant recent weight loss

 Associated with poor glycemic control

 Patients without distal symmetrical polyneuropathy most often have sudden, unilateral onset

 Occasionally the initial presenting feature of diabetes mellitus

Examination

 Proximal lower limb muscle weakness and wasting

 Minimal sensory loss is observed

 Knee-jerk reflex is absent, with commonly preserved ankle jerks

 Ankle jerks may also be absent, with underlying distal symmetrical polyneuropathy

Investigations

 Fasting blood glucose and HbA1C

 Imaging of lumbo-sacral spine to exclude other causes

 EMG and nerve conduction studies

Treatment

 Optimize glycemic control

 Physical and occupational therapy

Table 31

Vasculitic neuropathy [53, 54]

History

 May be part of systemic vasculitis or a non-systemic vasculitic neuropathy

 Asymmetric or multifocal painful sensorimotor neuropathy is most common presentation

 May present as mononeuritis multiplex or a sensorimotor neuropathy, which may or may not be symmetric

 Typically sensory symptoms of pain, burning, or paresthesias precede weakness of muscles supplied by the affected nerve

 Sensory symptoms virtually always present

 Constitutional symptoms, including weight loss, anorexia, fatigue, arthralgias, myalgias, and fevers, occur in approximately two-thirds of patients

Examination

 Detailed neurological exam reveals a flaccid asymmetric paresis with sensory abnormalities in variable distributions

 Lower limbs are more commonly involved than upper limbs

 Distal involvement is more frequent than proximal

 Cranial nerve involvement occurs in 8 % of patients, typically involving the facial nerve

 Proximal symmetric polyneuropathy is least frequent presentation

Investigations

 Vasculitic screen, including erythrocyte sedimentation rate, anti-nuclear antibodies, extractable nuclear antigens, rheumatoid factor, anti-neutrophil cytoplasmic antibodies, hepatic enzymes, renal function tests, serum complement serum immunoelectrophoresis (or immunofixation) and quantitative immunoglobulins, cryoglobulins, Hepatitis B antigen and antibody, Hepatitis C antigen, and CBC (anemia)

 Nerve conduction studies and EMG

 Nerve and muscle biopsy

Treatment

 Consider combination therapy with steroids and cyclophosphamide in liaison with treating neurologist

 Manage neuropathic pain with agents such as gabapentin, amitriptyline, nortriptyline, or carbamazepine

Table 32

Toxin-induced peripheral neuropathy [55]

History

 Many drugs and industrial chemicals may cause distal axonopathy

 Drugs include alcohol, amiodarone, chloramphenicol, disulfiram, isoniazid, lithium, metronidazole, nitrofurantoin, nitrous oxide, thalidomide, vincristine, and thallium. Dose, duration of exposure and host factors affect outcome

 Presentation is often with pain, paresthesiae, and hypoesthesia in the feet, with distal weakness and gait disturbance

 Autonomic dysfunction may be present

Examination

 Sensory changes in glove and stocking distribution

 Distal weakness progressing proximally

 Hyporeflexia, symmetrical loss of ankle jerks first

 May be evidence of CNS involvement

Investigations

 EMG

 Nerve conduction study

 Serum levels for suspected toxin

 Consider nerve and muscle biopsies

Treatment

 Prevent ongoing exposure

 Supportive care

Table 33

Nerve compression syndromes [56, 57]

History

 History of acute or prolonged neural pressure causing a radiculopathy, plexopathy, or peripheral neuropathy

 History depends on the region involved

 Pain and paresthesias typically precede hypoesthesia and weakness/atrophy

 Common specific examples include median nerve at wrist, ulnar nerve at elbow and wrist, radial nerve in proximal forearm, scapular nerve, lateral femoral cutaneous nerve, common peroneal nerve, tibial nerve, and lower brachial plexus

 May be caused by pregnancy, obesity, or systemic conditions (e.g., hypothyroidism)

 Nerve root weakness from a prolapsed intervertebral disc produces symptoms in the affected dermatome and myotome

Examination

 Reduced strength in the muscles supplied by the affected nerve

 Flaccid, hypotonic, hyporeflexic paralysis

 Wasting and atrophy if chronic

 Sensory symptoms include pain, paresthesias, and hypoesthesia

 Skin changes include dry, thin, hairless skin; ridged, thickened, cracked nails; and recurrent skin ulceration

Investigations

 Nerve conduction studies

 MRI

 Consider EMG

Treatment

 Treat or remove precipitants

 Surgery if conservative management fails

Table 34

Acute poliomyelitis [58]

History

 Typically occurs in unvaccinated patients from an area with endemic polio (Afghanistan, India, Nigeria, Pakistan, Angola, Chad, and Democratic Republic of the Congo)

 However, may rarely occur after receiving live attenuated vaccine

 Only a minority of infections (<5 %) experience paralytic poliomyelitis

 Flaccid asymmetric weakness and muscle atrophy, lower limbs more than upper limbs

 Incubation period 4 days–5 weeks

 Severe muscle pain and spasms are followed by weakness

 Bulbar symptoms are more common in adults

 Transient acute urinary retention in 50 %

Examination

 Asymmetric proximal weakness is typically present, with more involvement of lumbar than cervical segments

 Sensation is preserved

 Deep tendon reflexes are diminished or absent

 Atrophy of muscle may be detected three weeks after onset of paralysis, which becomes maximal at 12–15 weeks and remains permanent

 Cranial nerves may also be affected uni- or bi-laterally

Investigations

 Elevated WBC

 CSF: pleocytosis, mildly elevated protein with normal glucose

 Viral studies for throat swab, stool, blood, and CSF

 MRI may show localization of inflammation to the spinal cord anterior horns

 EMG

Treatment

 Supportive care

Table 35

Hypermagnesemia [59]

History

 Typically follows excessive magnesium administration in context of renal impairment

 More likely when supranormal magnesium levels targeted (e.g., in management of pre-eclampsia)

 Lethargy and confusion are most common neurologic manifestations

 As concentrations rise, generalized weakness develops, which progresses to involve muscles of respiration resulting in respiratory failure

Examination

 Hyporeflexia: early loss of deep tendon reflexes often precedes other signs

 Flaccid tetraparesis involving all muscle groups

 Lethargy, confusion

Investigations

 Serum magnesium levels

Treatment

 Cease magnesium administration

 IV calcium gluconate or chloride if symptoms severe

 IV fluids

 Consider dialysis

Table 36

Hypophosphatemia [6062]

History

 Hypophosphatemia may occur with

  Intracellular shift: re-feeding syndrome, respiratory alkalosis, diabetic ketoacidosis, rapidly growing malignancies, osmotic diuresis, certain drugs including diuretics, malabsorption, renal tubular acidosis

  Increased urinary excretion: primary or secondary hyperparathyroidism, osmotic diuresis (e.g., hyperosmolar hyperglycemic syndrome), diuretics, renal tubular acidosis, transplanted kidneys, congenital defects, or Fanconi syndrome)

  Decreased intestinal absorption: diarrhea, malabsorption syndromes, phosphate binders (e.g., aluminum hydroxide)

  Decreased dietary intake: anorexia nervosa or chronic alcoholism

 Weakness may present as a painful proximal myopathy

 Other neurological symptoms may include changes in mental function, seizures, and neuropathies

 Other features may include arrhythmias, skeletal muscle weakness, respiratory failure, rhabdomyolysis, leukocyte dysfunction, sepsis, and sudden death

Examination

 Proximal muscle weakness is common, though any muscle group may be involved, alone or in combination, ranging from ophthalmoplegia to proximal myopathy to dysphagia or ileus

 Muscle pain is common

 Weakness may be so profound as to mimic Guillain–Barre syndrome [60, 62]

 Confusion, seizures, and coma may occur

 Impaired cardiac contractility may occur, leading to generalized signs of myocardial depression

Investigations

 Serum phosphate

 Hypomagnesemia is commonly associated

 Hypercalcemia if hyperparathyroidism

 Urea, creatinine, other electrolytes

 Rhabdomyolysis screen

Treatment

 Correct precipitant

 Replace total body phosphate with careful IV sodium or potassium phosphate

Communication

A checklist of items to consider with assessment and referral for affected patients is provided in Table 37.
Table 37

Acute weakness communication with assessment and referral

\(\square\) Cause of weakness if known; differential diagnosis if not known

\(\square\) Airway status and any respiratory issues

\(\square\) Salient history and exam findings

\(\square\) Relevant labs and imaging (if done)

\(\square\) Treatments provided

Copyright information

© Neurocritical Care Society 2012