Syringomyelia is the progressive formation of a cavity or syrinx within the spinal cord that compresses the grey spinal cord tissue causing a variety of neurological symptoms.1 It has traditionally been categorized as either congenital or acquired. The congenital form is associated with Arnold-Chiari malformation and is the most common presentation (80-85%).2 This is referred to as “communicating” syringomyelia due to an initial or persisting continuity between the syrinx and cerebrospinal fluid (CSF) in the central canal of the spinal cord. The acquired form, also known as “non-communicating” syringomyelia, can be related to many factors, including inflammatory, neoplastic, and traumatic etiologies.

Post-traumatic syringomyelia (PTS) is typically seen following trauma to the spinal cord, and many theories have been proposed to explain its pathogenesis,3,4 including cavitation following spine ischemia or infarction, arachnoiditis, inflammatory response, and intraparenchymal hematoma and its subsequent absorption leaving a cystic cavity.5,6 According to Di Lorenzo et al.,2 all types of syringomyelia have a common underlying cause, i.e. the alteration of normal CSF flow due to blockage at some level of the subarachnoid space.

The prevalence of syringomyelia was estimated to be around 9 per 100,000, and 25% of those were associated with PTS.5 It is important to note that this estimation was proposed prior to the widespread use of magnetic resonance imaging (MRI), so the actual prevalence is likely to be much higher. A prevalence as high as 130 per 100,000 has been reported recently in some regions of the Russian Federation.7,8 It is estimated that 1-9% of patients with spinal cord trauma have the likelihood of developing symptomatic syringomyelia within 30 years of trauma.5

Although a few cases of peripartum management of patients with syringomyelia have been reported in the literature, these reports are described in the context of congenital form and not PTS.1,9-14 We present the successful peripartum anesthetic management of a parturient suffering from PTS. The patient gave written informed consent for the publication of this case report.

Case presentation

A 30-yr-old woman, gravida 3 para 1, presented to the preadmission clinic at Mount Sinai Hospital for anesthetic consultation at 31 weeks’ gestation. She was diagnosed with cervical PTS secondary to a whiplash injury to her spine sustained in a motor vehicle accident three years earlier.

Her symptoms started within a few days after the accident and involved pain in the cervical spine and torticollis toward the right side. The pain in her cervical spine evolved over time to include upper and lower thoracic as well as lumbar spine and paraspinal areas. Her back pain increased significantly with Valsalva maneuvers, such as bearing down, coughing or sneezing, and prevented her from walking normally or sitting upright in a chair. She had decreased sensations below C2 dermatome and diffuse non-focal weakness involving her arms, mainly the left. She also experienced a few spontaneously resolving syncopal episodes which were preceded by severe pain and dizziness. She denied other symptoms of autonomic dysfunction.

Eight months following her accident, she was referred to a neurosurgeon for further investigations. Magnetic resonance imaging of her spine revealed a cervico-thoracic syrinx of 2 mm in diameter extending from C4 to T1 level with disc protrusions in the C4-C6 region indenting the thecal sac without cord compression (Figure). There was no evidence of Arnold-Chiari malformation or raised intracranial pressure (ICP).

Figure
figure 1

Magnetic resonance imaging scan of the spinal cord at the cervicothoracic level revealing a 2-mm dilated syrinx in the central canal from C4 to T1 (arrow at C7 level). Sagittal view (A) and axial view (B). There is no Arnold-Chiari malformation

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The patient also had a history of childhood asthma, sickle cell trait, depression, and anxiety. Her medications were fluoxetine, trazadone, clonazepam, famotidine, and oxycodone 120 mg daily (40 mg in the morning and 80 mg at night). She smoked medicinal marijuana two to three times a day. On physical examination at 31 weeks’ gestation, she was found to be 165 cm tall and her weight was 84.5 kg. She was distressed because of her back pain, and she walked slowly with some limp. Her vital signs were stable, and airway examination revealed Mallampati class 2 score with limitations in the range of her neck movements in all directions due to a firm mass in the left shoulder area and torticollis. Her spinous processes could not be palpated due to spasm of her paravertebral muscle columns. Her lumbar spine was lordotic, and she could not voluntarily reverse this lordosis because of her back pain. No evidence of scoliosis was found.

In preparation for her delivery, thorough planning was carried out by a team consisting of an obstetrician, an anesthesiologist, a neurosurgeon, a neonatologist, and a psychiatrist. Another MRI of her spine was ordered, which showed no changes in the size of her syrinx. After consultation with the neurosurgeon, obstetrician, and the patient, it was decided to perform an elective Cesarean delivery at 393/7 weeks’ gestation. We discussed the options of both general and regional anesthesia with the patient and informed her about the lack of anesthesia literature in patients with PTS. The risks of changes in CSF dynamics and pressure during tracheal intubation and spinal anesthesia were explained to the patient. The usual risks of general anesthesia in pregnant patients, such as possible aspiration and difficult tracheal intubation were also discussed. Titrated epidural anesthesia was considered a preferred choice due to the possibility of less CSF pressure change and the ability to use the epidural catheter postoperatively for pain management. Both the patient and the obstetrician were informed about the risk of unintentional dural puncture and its unknown consequences in patients with PTS. We reassured both of them that measures would be taken to minimize these risks, and we agreed to have the most senior anesthesiologist available perform the epidural procedure.

There was no change in the patient’s neurological condition or vital signs on the day of the planned Cesarean delivery. Premedication of ranitidine 50 mg and metoclopramide 10 mg was given intravenously. Epidural anesthesia was performed with the patient in the sitting position after determining the L3-4 interspace, the needle insertion point, and the estimated depth to the epidural space by ultrasonography. To position her comfortably, she was administered fentanyl 100 μg intravenously in aliquots of 50 μg each. Using an 18G Tuohy needle, the epidural space was located through the pre-determined insertion point by loss of resistance to saline technique. Anesthesia was established by slowly injecting 2% lidocaine with epinephrine 1:200,000 (in aliquots of 3-5 mL for a total of 25 mL) with fentanyl 50 μg. A bilateral sensory block height of T4 was achieved. The patient’s preoperative blood pressure was 120/60 mmHg and her heart rate was 85 beats·min−1. Her blood pressure was maintained within 10% of the baseline levels throughout the procedure using vasopressors (intravenous phenylephrine 400 μg total) and lactated Ringer’s solution (1,500 mL total). A healthy neonate was delivered with Apgar scores of 8 and 9 at one and five minutes, respectively; the neonate did not require ventilatory assistance. After the delivery, the patient received an intravenous infusion of oxytocin (20 units·L−1 at the rate of 150 mL hr−1), epidural morphine 2.5 mg, ketorolac 30 mg iv, and acetaminophen 1,300 mg rectally. She was given oral diclofenac 50 mg every eight hours and acetaminophen 1 g every six hours in addition to her daily analgesic medications. Patient-controlled analgesia was offered, but the patient refused it. She received a total of 20 mg of intravenous morphine for breakthrough pain during the first two days postpartum. Her abdominal pain was under control; however, she continued to have back pain. No other complications were encountered, and she was discharged three days after the Cesarean delivery.

Discussion

Our patient presented with the diagnosis of PTS with chronic pain syndrome and was managed successfully for Cesarean delivery under epidural anesthesia.

Patients with syringomyelia may present with diverse pathophysiology and clinical features. The clinical manifestations include altered pain and temperature sensations in the upper limbs (lateral spinothalamic tracts), flaccid weakness in the upper limbs and shoulder girdle (anterior horn cells), and spastic paresis in the lower limbs (corticospinal tracts). Weakness of the paraspinal musculature may lead to thoracic scoliosis.2 The presence of posterior column signs usually signifies advanced disease. Involvement of the autonomic nervous system is not uncommon. Syringomyelia associated with Arnold-Chiari malformation may present with signs of increased ICP. As these two conditions are closely associated with each other in the majority of cases, Arnold-Chiari malformation must be ruled out when syringomyelia is diagnosed.2 These patients should undergo a comprehensive preoperative assessment that includes the degree of neurological deficits and, signs of increased ICP and autonomic neuropathy.

The CSF flow dynamics in patients with syringomyelia may have implications during labour, delivery, and anesthetic management of these patients. The pathophysiology of the development of a syrinx is still poorly understood. An “intramedullary pulse pressure theory” has been proposed recently to explain the hydrodynamics of syringomyelia. The theory suggests that a syrinx is caused by increased pulse pressure in the spinal cord that is greater than that in the nearby subarachnoid space.15 The pressure in the syrinx is higher than that in the surrounding CSF and is influenced by changes in subarachnoid space compliance. In patients with PTS, the presence of a locally tethered cord or a blockage by arachnoid scarring may diminish subarachnoid space compliance, which can lead to an increase in CSF inflow. Consequently, syrinx enlargement, cord enlargement above or below obstruction, or cord dissection can occur.5,15

It is possible that the process of labour itself, similar to coughing and straining, can be a precipitating factor for syrinx enlargement.16 Therefore, in our case, Cesarean delivery was preferred over vaginal delivery to avoid sudden clinical deterioration and worsening of neurological symptoms. Although vaginal delivery is not contraindicated, an assisted second stage is advocated.17

The challenges in the anesthetic management of our case included: (a) potential difficulty in the placement of regional block due to lumbar spine hyperlordosis, pain, and paraspinal muscle spasms; (b) considerations for avoiding pressure changes within the syrinx due to administration of spinal or epidural drugs and pressor response during general anesthesia; (c) potential difficulty in tracheal intubation due to a dystonic neck mass; and (d) difficult postoperative pain management due to the patient’s chronic high-dose opioid use.

Spinal anesthesia may not be a preferred option for Cesarean delivery in patients with PTS, as abrupt changes in CSF pressure as well as severe hypotension are to be avoided, especially in the event of disautonomia. Spinal anesthesia could also produce unpredictable effects due to abnormal CSF flow dynamics in these patients. Two case reports of aggravated signs and symptoms within two weeks of dural puncture have been described in syringomyelia associated with Arnold-Chiari malformation.18-20

Daskalakis et al. 1 described an uncomplicated elective Cesarean delivery under general anesthesia in the presence of PTS. The authors discussed both general and epidural anesthesia as possible techniques. However, several critical issues have to be considered while providing general anesthesia in such patients, including avoidance of increase in ICP and pressure changes in the syrinx as a result of pressor response during intubation, coughing, vomiting, hypoxia, or hypercarbia. Close hemodynamic monitoring is also necessary in patients with autonomic neuropathy. Other issues with the administration of general anesthesia include ventilation-perfusion abnormalities due to vertebral column deformities and an unpredictable response to muscle relaxants in patients with neurological involvement.21,22 Our patient had severe torticollis and a dystonic muscle mass in the neck, which might have posed an additional problem during airway intervention.

Epidural anesthesia was chosen in our case as it may offer several advantages over spinal and general anesthesia in patients with PTS. These benefits include avoidance of the potential hazards of securing the airway, reduced incidence of hypotension and deterioration of autonomic neuropathy, and minimal change in the existing CSF pressure relationship if the medication is titrated gradually. The difficulty in epidural placement due to the hyperlordotic state in our patient was overcome by prior administration of intravenous fentanyl and use of ultrasound for accurate localization of the landmarks. Moreover, the procedure was performed carefully by a senior anesthesiologist and not by a trainee. Although the possibility of accidental dural puncture with an epidural needle and subsequent alterations in CSF pressures cannot be ruled out, the above measures decreased the likehood of such events. There is still a possibility of sudden distension of the epidural space due to the local anesthetic injection, which in turn could induce subarachnoid space compression thereby increasing ICP and creating a potentially damaging pressure wave within the syrinx.10,23,24 To minimize this problem, gradual titration of local anesthetic was instituted through an epidural catheter. Considering the patient’s chronic pain syndrome, the added advantage of placing an epidural catheter was to provide additional local anesthetics and opioids if required in the postoperative period.

The successful management of this case suggests that an epidural can be considered in women with post-traumatic cervical syringomyelia presenting for a Cesarean delivery.