The incidence of the chromaffin cell tumour , phaeochromocytoma, is ≈0.13% . It occasionally occurs in multiple endocrine neoplasia associated with thyroid carcinoma, parathyroid adenoma and mucosal adenomas . Phaeochromocytoma is particularly important to the anaesthesiologists because of the high mortality when the tumour is undiagnosed preoperatively . The induction of anaesthesia is an especially dangerous period.
The present authors report the anaesthetic management of a patient for cerebral aneurysm surgery who had a coexisting phaeochromocytoma.
A 48-year-old woman was admitted to hospital complaining of an intractable headache after she had squatted down suddenly. For 10 years, she had suffered headaches that had come on after palpitations and nausea. She had 3+ neck stiffness, but no other neurological findings. A diagnosis of grade 1 subarachnoid haemorrhage was made. Cerebral angiograms performed the next day showed an anterior communicating artery aneurysm and bilateral middle cerebral artery aneurysms. The subject had a sudden attack of sweating and palpitations after the angiogram, and her blood pressure reached 180/120 mmHg.
The patient's full blood count was normal. Blood glucose was slightly raised, but there were no other biochemical abnormalities on routine screening. Her catecholamine metabolites were measured because of her sweating attack after angiography. The level of urinary vanyl mandelic acid (VMA) was 13.6 μg VMA mg−1 creatinine (normal range=0-6 μg VMA mg−1 creatinine), and total vanyl mandelic acid was 10.56 mg 24 h−1 (normal range=0.7-6.8 mg 24 h−1). Abdominal ultrasonography and computerized tomography showed a 65 × 85 mm left suprarenal cystic mass, which was possibly a phaeochromocytoma.
Pre-operatively, prazosin 0.5 mg and propranolol 20 mg were given orally every 6 h. The blood pressure was kept between 110/70 and 140/90 mmHg. It was planned to clip the aneurysms on the tenth day after the subarachnoid haemorrhage.
The patient did not need premedicant drugs. Three electrocardiogram electrodes were placed in the CM5 position, and a pulse oximeter probe, a non-invasive blood pressure cuff and an axillary temperature probe were also used. The left radial artery was cannulated with a 20-gauge catheter to monitor blood pressure and to collect samples for blood gas analysis.
Anaesthesia was induced with propofol (2 mg kg−1), followed by fentanyl (2 mg kg−1). Dexamethasone (16 mg), furosemide (40 mg) and lignocaine (100 mg) were given a few minutes before tracheal intubation, for which vecuronium bromide (0.1 mg kg−1) was injected. After induction, a 16-gauge femoral vein catheter was inserted to measure central venous pressure. A gas analyser was connected to the endotracheal tube to monitor carbon dioxide, oxygen, nitrous oxide and isoflurane.
Anaesthesia was maintained with 50% nitrous oxide and 0.6-1% end-tidal isoflurane in oxygen. Increments of fentanyl (2 μg kg−1) were given when necessary. The operation lasted 10 h. The arterial partial pressure of carbon dioxide was 4.2-4.7 kPa throughout the operation. A total of 5000 mL crystalloid solution, 700 mL colloid solution and 2 units of blood were given; the urine output was 3300 mL and estimated blood loss was 1100 mL. A nitro-glycerine infusion was used for short periods during the induction and emergence to maintain the blood pressure within the physiological range.
The mean arterial pressure was kept between 70 and 75 mmHg by titration with isoflurane while the aneurysms were being clipped. After the aneurysms had been clipped, the mean arterial pressure was gradually allowed to increase to 85-100 mmHg by rapid infusion of colloid solutions and blood.
The patient opened her eyes and responded to verbal commands shortly after the termination of anaesthesia. She remained haemodynamically and neurologically stable throughout the post-operative period.
One week later, the subject underwent removal of the left suprarenal mass, again without peri-operative complications. She was discharged from hospital 23 days after admission and was neurologically normal at this time.
Better diagnosis and pharmacological management have reduced the complications of phaeochromocytoma . The clinical manifestations of a phaeochromocytoma are often mistaken for signs of other neurological, cardiovascular or psychiatric disorders, and a high degree of suspicion is needed to make the diagnosis of this rare tumour. Surgical complications occur when there is an undiagnosed phaeochromocytoma: 27% of patients with undiagnosed tumours died of hypertensive or hypotensive crises during minor surgery . The operative mortality of patients with known tumours is 1.3% .
There have been reports of neurological symptoms in patients with phaeochromocytoma. In a series of 100 patients, 11 subjects had visual disturbances, or numbness and paraesthesia in the hands and face. Three patients had cerebral infarctions and two had intracerebral bleeding, although no mechanism for these findings was given . In one case report , cerebral vasospasm was seen in combination with angiography in a patient with phaeochromocytoma who had reported a 3-week history of headache. An acute stroke was also reported in a patient with phaeochromocytoma . This was ascribed to high catecholamine concentrations inducing a form of cerebral vasculitis rather than to vasospasm.
In the present subject, the neurological examination raised the suspicion of a subarachnoid haemorrhage and angiography confirmed three aneurysms. Phaeochromocytoma was suspected after the sweating, palpitations and hypertension following the angiography, and the diagnosis was supported by urinary concentrations of catecholamine metabolites.
The present authors' main concern was to maintain normal cerebral perfusion pressure so as to avoid cerebral ischaemia from possible vasospasm, and to avoid peaks of systolic pressure that might cause rebleeding or rupture of an aneurysm. The patient's blood pressure was maintained as close to normal as possible by titration of anaesthesia and nitroglycerine. The anaesthetic agents were chosen taking account of both the aneurysms and the phaeochromocytoma. Propofol was injected slowly at induction because of its proposed cerebral protective and antioxidant effects . Delivering fentanyl, lignocaine and isoflurane before laryngoscopy allowed the intubation of the trachea without haemodynamic disturbance. The present authors used isoflurane for maintenance of anaesthesia because it is easily titrated. It is also a potent depressor of cerebral metabolism which has little effect on cerebral blood flow .
The pharmacological and anaesthetic management of patients with cerebral aneurysms and phaeochromocytoma is complex, and needs to be managed carefully by titrating anaesthetic agents and vasoactive drugs. The primary concern is the maintenance of cerebral perfusion pressure and autoregulation throughout the procedure. Because the present patient survived the operation neurologically intact, it can be presumed that the management approach which was adopted helped to achieve this outcome.
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