Intraoperative Patient Positioning and Neurological Injuries

Abstract

Thoracic cases usually involve repositioning the patient after induction of anesthesia. Vigilance is required to avoid major displacement of airway devices, lines, and monitors during and after position changes. Obtaining central venous access after changing to the lateral position is extremely difficult. If a central line may be needed, it should be placed at induction. Prevention of peripheral nerve injuries in the lateral position requires a survey of the patient from the head and sides of the operating table prior to draping. Post-thoracotomy paraplegia is primarily a surgical complication.

Clinical Case Discussion

A 60-year-old woman presents for a left thoracotomy for left lower lobectomy for lung cancer. Past medical history includes a remote myocardial infarction with a preoperative ejection fraction of 40%, controlled hypertension, and diet-controlled diabetes mellitus. Regular medications are taken the morning of the OR, including metoprolol and aspirin 81 mg. A flexible epidural catheter with inner stainless steel coil wire is placed at T6/7 for postoperative analgesia. After an epidural test dose of 3 ml lidocaine 2%, an infusion of bupivacaine 0.1% plus hydromorphone 15ug/ml is started at 5 cc/h. A central line is placed after induction. The operation is remarkable for intraoperative hypotension requiring dopamine and norepinephrine and brisk bleeding near the costovertebral junction. Immediately postoperatively, blood pressure is in the patient’s normal range with no support, there is no motor deficit, and pain is well-controlled. Six hours postoperatively, a nurse from the ward calls to report that the patient is complaining of bilateral lower extremity motor weakness.

• 1. What is the differential diagnosis?

At this point, the differential is wide and includes a motor block secondary to epidural local anesthetic solution, an intrathecal catheter, compression of the nerve roots or spinal cord from an epidural hematoma or a foreign body, arterial embolus to a radicular artery, or a hypoperfusion state.

• 2. What should be done immediately?

Vital signs should be taken and documented, the epidural solution should be stopped, and the catheter should be aspirated. A focused chart review should be undertaken with special note taken of any recently administered anticoagulants. The surgeon should be called and be advised of the problem. A complete neurological examination should be performed.

• 3. What does the initial assessment reveal?

The patient is awake and alert. Her blood pressure is 89/65 with a normal heart rate and oxygen saturation. No blood or CSF is aspirated through the catheter. She is unable to move her legs. She has loss of sensation to pain and temperature in both legs, but proprioception is intact. Thirty minutes after the epidural solution has been turned off, there is no change in her neurological status. The last documented INR is 1.29 5 h ago. The patient received subcutaneous heparin for DVT prophylaxis 1 h ago.

• 4. What should be done next? What bloodwork, imaging, and consults should be ordered?

Dopamine is started through the patient’s central line to keep the blood pressure in her normal range (120/80) with continuous cardiac monitoring. “STAT” complete blood count and coagulation tests are drawn. There is hesitance to remove the epidural catheter in the context of a coagulation abnormality combined with recent heparin administration and aspirin. MRI is the preferred modality to diagnose an epidural hematoma. However, the in situ epidural catheter is not permitted in the scanner. After consultation with the radiologist, the epidural is left in place, and a CT is performed. The neurosurgeon and neurologist are called and made aware of the patient.

• 5. What is found on additional testing?

The CT shows no epidural hematoma or mass. The hemoglobin is 90 g/L. Platelets are normal. INR is 1.21. The patient is seen by the neurologist and given a provisional diagnosis of spinal cord ischemia causing an anterior cord syndrome.

• 6. What else can be done?

The patient is moved to a step-down unit with continuous monitoring. Neurologic vitals are done every 4 h. Dopamine is continued, and the patient is given 100 mg methylprednisolone IV q8h × 3 doses. Hemoglobin is maintained at 100 g/L. The epidural is removed 6 h after the last subcutaneous heparin dose. An MRI is then performed and is normal. Pain is controlled with hydromorphone intravenous PCA. Over the next 4 days, the patient gradually and completely recovers.