Department of Anaesthesia Intensive care and Pain Management, St Vincents University Hospital, Elm Park, Dublin 4, Ireland
*Corresponding author: Intensive Care Unit, Middlesex Hospital, Mortimer Street, London W1T 8AA, UK. E-mail: patrickbreen@eircom.net Presented on 16 May 1997 at the Annual Scientific Meeting, Royal College of Anaesthetists, Royal College of Surgeons in Ireland, Dublin, Ireland.
Accepted for publication: August 18, 2003
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Abstract |
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Br J Anaesth 2004; 92: 2868
Keywords: brain, ventral pons; complications, cranial nerve palsy; complications, postoperative neurological deficit; complications, synovial sarcoma; complications, tetraplegia
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Introduction |
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Case report |
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Anaesthesia was induced with fentanyl and propofol. Vecuronium 6 mg was given to allow insertion of a left-sided, double-lumen endobronchial tube and a further 4 mg to maintain neuromuscular blockade. Anaesthesia was maintained using isoflurane (FE' 0.51.5%) with nitrous oxide 660% in oxygen. Arterial and central venous pressures were measured with appropriate cannulae. The patient was carefully positioned on her left side with the head and neck in a neutral position, and a right upper lobectomy was performed. Systolic pressure remained within 20% of the conscious value, which was 110 mmHg. SpO2 was never less than 95%. Morphine was given for analgesia (total intraoperative dose 10 mg), and intercostal blocks were done under direct vision by the surgeon, using bupivacaine 0.25%, 10 ml.
Neostigmine 2.5 mg and glycopyrrolate 0.5 mg were given i.v. to antagonize neuromuscular blockade, and spontaneous respiration started. Oxygen 100% was given and the patient was carefully placed in the supine position with the head and neck in the neutral position. She remained deeply unconscious. Her vital signs were stable. The trachea remained intubated. The pupils were constricted and did not react to light. A painful stimulus caused eye opening and decerebrate posturing. Arterial blood gas analysis and blood glucose values were normal. A computed axial tomographic (CAT) brain scan, done without contrast enchancement, showed no abnormality. Blood electrolytes, and renal and liver function tests were normal.
The following morning, a second CAT scan was performed with contrast enchancement. This showed two low-density lesions in the right cerebellar hemisphere, one in the left side of the pons and one in the thalamus. The patient received ventilatory support and was sedated with morphine and midazolam. Four days later a diagnosis of locked-in syndrome was confirmed. The only voluntary effort was vertical eye movement. The patient was able to understand and respond appropriately to commands. She communicated by moving her eyes upwards for no and downwards for yes.
Histological examination of the resected lobe of lung confirmed metastatic synovial sarcoma. Tumour was present within and adjacent to the pulmonary vein.
The patients neurological condition remained stable, with no arm or leg movement. After tracheostomy, she breathed spontaneously. A magnetic resonance scan showed probable metastatic disease in the brain stem. The patient remained in a locked-in state and died 7 months later.
Post-mortem examination revealed a basilar artery occlusion caused by a tumour embolus (metastatic synovial sarcoma). The ventral pons was extensively replaced with metastatic tumour. The tumour appeared to arise from within the artery, extending through the vessel wall into the surrounding pons. It was not possible to determine when tumour embolism had occurred. Other findings were a small intraventricular haemorrhage, bilateral Wallerian degeneration of the corticospinal tracts at the level of the pons, caused by metastatic tumour, bilateral symmetrical olivary hypertrophy, and sarcomatous metastases in both kidneys and in the right adrenal gland.
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Discussion |
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Locked-in syndrome is usually caused by pontine infarction after prolonged vertebrobasilar ischaemia.4 Other causes include haemorrhage, tumour,5 trauma,6 central pontine myelinolysis,7 pontine abscess,8 interscalene brachial plexus blocks9 and postinfective polyneuropathy.10 Cerebral air embolism and transient vertebrobasilar insufficiency are potentially reversible causes. The site of the lesion is usually in the basis pontis and there may be variable involvement of the pontine tegmentum, medulla and midbrain.1 Preservation of voluntary eye movements occurs when the lesion remains caudal to the nucleus of the oculomotor nerve; consciousness is preserved when the reticular formation in the dorsal pons is unaffected by the lesion. The diagnosis can be made clinically. The prognosis after ventral pontine infarction is often fatal from respiratory failure or extension of the infarct. Recovery can occur from the locked-in syndrome,11 but most survivors remain in a chronic locked-in state or are severely impaired. Significant recovery may occur when the duration of the syndrome is less than 24 h, usually after a transient ischaemic attack.
Perioperative locked-in syndrome following coronary artery bypass graft has been described on two occasions.2 12 One case, occurring a few hours after surgery, was attributed to cerebral air embolism, with air bubbles noted in the grafts during surgery.12 Recovery was complete after treatment in a hyperbaric oxygen chamber. Kenny and colleagues2 described basilar artery embolism causing the syndrome within 24 h of surgery. The patient remained in a locked-in state.
We suspect that our patient developed locked-in syndrome from a tumour embolus that occurred during surgery. The clinical features were not apparent at first. Decerebrate posturing is not typical. The low-density changes seen on the contrast-enhanced CAT scan may have been caused by infarction. This was confirmed at autopsy. Tumour was found in the pulmonary vein of the resected lobe. The pulmonary artery is usually ligated before the vein. This reduces bleeding from the lung during resection but may increase the likelihood of tumour embolization.
How relevant is this case report to anaesthetic practice? The locked-in syndrome is an unlikely reason for delayed recovery from anaesthesia, and other causes should be excluded first. Some patients may have an increased risk of developing the syndrome during surgery. Cervical osteoarthritis can cause vertebrobasilar insufficiency if osteophytes compress the vertebral artery during neck movements. Patients with this condition should therefore be positioned carefully when anaesthetized, with their head and neck in the neutral position. Inadvertent vertebral artery injection during interscalene brachial plexus block may cause the syndrome. Emboli from atheroma can occur after cannulation of an atherosclerotic proximal aorta.13 This is best detected by epiaortic ultrasonography.14 Locked-in feelings have also been reported in patients receiving neurolept anaesthesia.15 Synovial sarcomas are malignant high-grade neoplasms that account for 78% of all malignant soft-tissue tumours and are quite common in young people. Complete resection remains the treatment of choice.16
We present a case of locked-in syndrome associated with metastatic disease. Careful preoperative evaluation may serve to identify patients at particular risk of developing such complications during surgery.
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References |
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