Deliberate hypotension for intracranial aneurysm surgery: changing practices

White Matter Lesions as Brain Frailty and Age are Risk Factors for Surgical Clipping of Unruptured Intracranial Aneurysms in the Elderly

INTRODUCTION

We aimed to identify the risk factors for surgical treatment of unruptured intracranial aneurysms (UIAs) in individuals aged >60 years, particularly focusing on white matter lesions (WMLs).

MATERIAL AND METHODS

We investigated a total of 214 patients with UIAs. The patient group comprised 53 males and 151 females with an average age of 68.2 years. UIA size ranged from 2.7 to 26 (mean: 7.3) mm. The primary endpoint of the study was patient prognosis evaluated at the time of discharge using the modified Rankin Scale. We examined the risk factors for poor outcome and WMLs using magnetic resonance imaging.

RESULTS

Poor outcome was observed in 23 (10.7%) patients. Significant correlations were observed between poor outcome and UIA size (P < 0.0001), UIAs located posteriorly (P = 0.0204), UIA thrombosis (P = 0.0002), and presence of WMLs (P < 0.0001) in univariate regression analysis. However, no significant correlations were noted between poor outcome and age (P = 0.1438). Multivariate logistic regression analyses showed significant correlations between poor outcome and UIA size (P < 0.0001), presence of WMLs (P = 0.001). Severe WMLs based on the Fazekas classification was correlated to age (P < 0.0001) and atherosclerosis (P = 0.0001). Severe WMLs were associated with ischemia (P < 0.001) and epilepsy (P = 0.0502) as well as length of hospitalization (P < 0.0001).

CONCLUSION

Severe WMLs are risk factors for surgical treatment of UIAs in the elderly. Surgical indications must be considered and caution should be taken when managing patients with severe WMLs.

[Peroperative risks in cerebral aneurysm surgery]

The perioperative complications associated with cerebral aneurysm surgery require a specific anaesthetic management. Four major perioperative accidents are discussed in this review. The anaesthetic and surgical management in case of rebleeding subsequent to the re-rupture of the aneurysm is mainly prophylactic. It includes haemodynamic stability assurance, maintenance of mean arterial pressure (MAP) between 80-90 mmHg during stimulation of the patient such as endotracheal intubation, application of the skull-pin head-holder, incision, and craniotomy. The aneurysmal transmural pressure should be adequately maintained by avoiding an aggressive decrease of intracranial pressure. Once the skull is open, the brain must be kept slack in order to decrease pressure under the retractors and avoid the risks of stretching and tearing of the adjacent vessels. If, despite these precautions, the aneurysm ruptures again. MAP should be decreased to 60 mmHg and the brain rendered more slack, in order to allow direct clipping of the aneurysm, or temporary clipping of the adjacent vessels. The optimal agents in this situation are isoflurane (which decreases CMRO2), intravenous anaesthetic agents (inspite their negative inotropic effect, they may potentially protect the brain) and sodium nitroprusside. Vasospasm occurs usually between the 3rd and the 7th day after subarachnoid haemorrhage. It may be seen peroperatively. The optimal treatment, as well as prophylaxis, is moderate controlled hypertension (MAP > 100 mmHg), associated with hypervolaemia and haemodilution, the so-called triple H therapy, with strict control of the filling pressures. Other beneficial therapies are calcium antagonists (nimodipine and nicardipine), the removal of the blood accumulated around the brain and in the cisternae, and possibly local administration of papaverine. Abrupt MAP increases are controlled in order to maintain adequate aneurysmal transmural pressure. Beta-blockers, local anaesthetics administered locally or intravenously, a carefully titrated level of anaesthesia, a maintained volaemia play a protective role. Cerebral oedema is sometimes already present at the opening of the skull or may arise later, due to a high pressure under the retractors, to the surgical manipulations of the brain or to brain ischaemia subsequent to temporary clipping. Its treatment is aggressive, with intravenous agents, mannitol, deep hypocapnia and/or lumbar drainage. Prophylaxis, according to the "brain homeostasis concept", is the preferred method to avoid these four peroperative accidents. It includes normal blood volume, normoglycaemia, moderate hypocapnia, normotension, soft manipulation of the brain and optimal brain relaxation.

Total intravenous anesthesia with propofol for burst suppression in cerebral aneurysm surgery: preliminary report of 42 patients

Forty-two patients underwent cerebral aneurysm clipping at our institution in 1991, 35 with a ruptured aneurysm and 7 with an unruptured aneurysm. Preoperatively, 22 patients with a ruptured aneurysm were graded I or II according to the World Federation of Neurosurgical Societies and 21 underwent an operation on the first day. All underwent a standard cerebral protective general anesthesia, combining propofol with fentanyl, arterial normotension (mild hypertension with volume loading and/or dopamine during temporary clipping and once the aneurysm was secured), normocarbia or slight hypocarbia, brain relaxation with lumbar drainage, mannitol and propofol, and electroencephalogram burst suppression when temporary clipping (> or = 2 min) was required. Propofol doses for induction were 1.8 +/- 0.1 mg/kg (mean +/- standard error); for maintenance, doses were 86 +/- 3.5 micrograms/kg per min; and for burst suppression doses were 500 micrograms/kg per min. After clipping, the propofol dose rate was reduced to allow early recovery and neurological examination in the operating room. In 21 patients, temporary clipping was required for a mean duration of 8.8 +/- 1.3 minutes (range, 2-29); none of these patients deteriorated as compared with their preoperative neurological state. Twenty-four of the 42 patients (57%) had a Glasgow Coma Outcome Scale (GOS) score of 1, 7 patients had a GOS score of 2, 8 had a score of 3, and 3 had a score of 5. Thirty-two patients were extubated in the operating room with a mean GOS Score of 13.2 +/- 0.5, and 10 were extubated later in the intensive care unit.(ABSTRACT TRUNCATED AT 250 WORDS)