|LETTER TO EDITOR
|Year : 2014 | Volume
| Issue : 3 | Page : 432-433
Transient brain stem ischemia following cervical spine surgery: An unusual cause of delayed recovery
Nirmala Jonnavithula1, Kavya Cherukuri1, Padmaja Durga1, Dilip Kumar Kulkarni1, Vijayasaradhi Mudumba2, Gopinath Ramachandran3
1 Department of Anesthesiology and Intensive Care, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India
2 Department of Neurosurgery, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India
3 Department of Neurosugery, Nizam's institute of Medical Sciences, Hyderabad, Andhra Pradesh, India
|Date of Web Publication||22-Jul-2014|
Department of Anesthesiology and Critical Care, Nizam's Institute of Medical Sciences, Punjagutta, Hyderabad - 500 082, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Jonnavithula N, Cherukuri K, Durga P, Kulkarni DK, Mudumba V, Ramachandran G. Transient brain stem ischemia following cervical spine surgery: An unusual cause of delayed recovery. J Anaesthesiol Clin Pharmacol 2014;30:432-3
|How to cite this URL:|
Jonnavithula N, Cherukuri K, Durga P, Kulkarni DK, Mudumba V, Ramachandran G. Transient brain stem ischemia following cervical spine surgery: An unusual cause of delayed recovery. J Anaesthesiol Clin Pharmacol [serial online] 2014 [cited 2020 May 28];30:432-3. Available from: http://www.joacp.org/text.asp?2014/30/3/432/137290
The causes of prolonged unconsciousness after anesthesia can be pharmacological, metabolic or organic. Recognizing the organic conditions is important as they require prompt surgical intervention to reverse the serious sequelae. Most cases of delayed recovery are usually attributed, at least in the beginning, to residual anesthetic effects. This approach, at times, may result in loss of valuable time in investigation and initiation of appropriate measures for rapidly reversible surgical causes. The operating team should be aware of such surgical causes to make objective decisions on postoperative imaging and follow-up action without any delay. Although cervical hematoma and compression of the vertebral artery is reported following cervical spine trauma, , brain stem ischemia due to hematoma in anterior cervical spine surgery is rarely reported. We report a case of coma and areflexia following vertebral corpectomy and anterior cervical disc fusion.
A 65-year-old male patient was admitted with cervical compressive myelopathy and central cord syndrome with C4-C5 subluxation. He was scheduled for a C5-C6 corpectomy, C3-C6 lateral mass plating and cage placement. There was no history of diabetes, hypertension, abnormal heart rhythm, transient ischemic attacks or giddiness. He was not a known alcoholic or a smoker. A standard general anesthesia was provided with propofol 2-3 mg.kg-1, fentanyl 2 μgkg-1 and tracheal intubation was facilitated with atracurium 0.1 mg.kg-1. Anesthesia was maintained with an inspired isoflurane concentration of 1.0MAC in 70% nitrous oxide, oxygen gas mixture and an infusion of atracurium and fentanyl. The patient was placed in supine position with hyperextension of the neck. The surgical procedure lasted for 150 minutes. There was bleeding from the vertebral body which was controlled by applying bone wax. Intraoperatively, the patient was hemodynamically stable. At the end of surgery which lasted for 150 min, the patient showed no signs of recovery from anesthesia even after 60 min of discontinuation of all anesthetic agents. The patient was comatose and unresponsive. Pupils were normal in size but not reacting to light. Suction of the trachea elicited no response; pharyngeal or laryngeal reflexes were absent. There was a flaccid paralysis of all the four limbs. There were no respiratory efforts. The patient was normothermic and hemodynamically stable throughout the observation period. Arterial blood gases, serum electrolytes and blood glucose were within the normal range. An increased collection of blood was noted in the closed suction drain suggesting bleeding at surgical site. As there was no pharmacological or physiological evidence for the absence of brain stem reflexes and unresponsiveness, an organic cause of hematoma compressing cervico-medullary area involvement was considered. The operative wound was immediately re-explored under sevoflurane, air and oxygen anesthesia. At the surgical site, a hematoma of 4 × 4 cms was noted compressing the vertebral artery, which was evacuated. The anesthetic was discontinued at the conclusion of the procedure. The patient regained spontaneous breathing and was able to move the limbs and obey commands within 15 minutes of discontinuation of sevoflurane. The pupillary reaction to light was restored. In view of the possible ischemic insult to the brain stem the patient was mechanically ventilated for 24 hours. There was a complete neurological recovery without any new deficits. Postoperative ECHO cardiogram, neck vessel doppler, MR angiography for evaluation of risk factors for cerebrovascular disease were unremarkable.
There are several anesthetic causes for delayed recovery. Most often delayed awakening is implicated to the anesthetic cause and organic conditions are often overlooked  especially when the surgery is remote from the brain. In the present report the patient developed transient brain stem ischemia which recovered completely after evacuation of hematoma which was compressing the vertebral artery. The bleeding might have resulted from dislodgement of the bone wax from the vertebral body after the surgical incision was closed. It is possible that the compression of the artery by the hematoma resulted in ischemia due to compromised blood supply of the brain stem and the patient manifested with the signs of coma and areflexia. Immediate exploration of surgical site was performed in view of the continued hemorrhage and prolonged unconsciousness which if due to cervico medullary area may become irreversible. This devastating complication could have been prevented if brain stem auditory and somatosensory evoked potentials (neurophysiological monitoring) had been employed. The evidence for brain stem ischemia in this report is only circumstantial; the location of the hematoma compressing the vertebral artery, and improvement of the neurological symptoms following evacuation prompted the diagnosis of brain stem ischemia though no confirmatory investigations were possible. There are several potential causes of brain stem ischemia during cervical spine surgery. Tsai and colleagues  described a case of fatal ischemic brain stem stroke resulting from the occlusion of the basilar artery during cervical spine surgery in a previously asymptomatic patient. Cervical traction, intraoperative manipulations of the severely inflamed vertebral artery, vibrations from a high-speed drill and prolonged hyperextension and rotation of the neck are a few possible mechanisms ,, that can result in occlusion of the blood flow to the vertebral artery causing brain stem ischemia. The contribution of these factors in causing vertebral artery injury cannot be clinically excluded in this case but the rapid reversal of ischemia favors compression due to hematoma. The restoration of blood flow is better in compressive injuries than in distractive injuries. It is because of lesser vasospasm and also a minor degree of stretch on the vessels which may cause reversible occlusion. 
Hematoma is a potentially reversible devastating complication. Many investigations which are recommended to confirm brain stem ischemia are not readily available in the OT complex. The duration of unconsciousness is affected by context-sensitive half-life, amount of drug, co-administration with other drugs, and patient factors. The initial endeavor of the anesthesiologist should be to find a reasonable explanation for the delay in recovery. In the absence of the above causes an organic cause should be contemplated. Waiting too long for a confirmatory diagnosis or under the assumption that anesthetic is responsible for delayed recovery may result in losing valuable time which may be detrimental to the outcome. Therefore, a bold decision to proceed with surgery based on clinical evidence may be rewarding in such circumstances.
This report highlights the importance of the vulnerability of vertebral artery to injury during the cervical spine surgery and hematoma as another potential cause brain stem ischemia during cervical spine surgery. Early recognition and prompt intervention is essential for forestalling the devastating and lethal complications.
At times a bold decision to proceed with surgery without waiting for substantiating the diagnosis may be rewarding.
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