Lumbar puncture should not be delayed in subarachnoid haemorrhage

Diagnosis of subarachnoid hemorrhage in the emergency department

To decide which patients with headache ought to be evaluated for SAH, physicians should focus on specific elements of the patient history, such as onset, severity, and quality of the headache and associated symptoms. These questions should be asked and the responses documented for every patient with a headache. The physical examination should be compulsive with regard to vital signs, HEENT. and neurologic signs. Then, the physician should form an explicit differential diagnosis and have reasons for diagnosing migraine, tension, or sinus headache and other benign causes. If there is no clear-cut alternative hypothesis, the patient should be evaluated by CT and LP (if the CT is negative, equivocal, or technically inadequate). Physicians should understand the limitations of this diagnostic algorithm. In addition, the CSF should be carefully analyzed, including measuring the opening pressure. In patients whose CT scans and CSF analyses are normal, further testing is rarely indicated.

How valuable is a lumbar puncture in the management of patients with suspected subarachnoid haemorrhage?

OBJECTIVE

The aim of the study was to determine the range of cerebrospinal fluid findings associated with emergency department disposition and treatment of patients with headache suspicious of subarachnoid haemorrhage but a negative or equivocal computed tomography head scan, in particular the role of xanthochromic index.

METHODS

A retrospective review of medical records of 196 adult patients who underwent cerebrospinal fluid examination for red cell count and xanthochromia for suspected subarachnoid haemorrhage but had a normal or equivocal computed tomography scan.

RESULTS

Included in the study were 196 patients. Only one patient out of 189 with a negative computed tomography scan was found to have a subarachnoid haemorrhage caused by a ruptured aneurysm (0.5%; 95% confidence intervals 0-2.9%). Three other patients were diagnosed with benign subarachnoid haemorrhage. Ninety-one patients were stratified into the lowest possible risk group for subarachnoid haemorrhage and discharged home from the emergency department. All patients with equivocal computed tomography head scans and a positive xanthochromic index were admitted for cerebral angiography. In many cases, cerebrospinal fluid findings did not appear to influence clinical decision-making.

CONCLUSIONS

In the study institution, cerebrospinal fluid results appeared to have a variable influence on clinical decision-making for patients with suspected subarachnoid haemorrhage and a non-diagnostic computed tomography head scan. Of particular concern is the lack of validation of the tests used in this investigative approach, the frequency of patients having a lumbar puncture where the results did not influence their management, the inconsistency in the laboratory's technique for performing tests on cerebrospinal fluid and the very low yield of detecting patients with subarachnoid haemorrhage and a potentially treatable causative lesion.

Subarachnoid haemorrhage

A high percentage of the population has aneurysms of the cerebral vessels, which are detected only by chance or after spontaneous rupture. Subarachnoid haemorrhage is still a problem because of high morbidity and mortality. Many patients do not fully recover neurologically and suffer from physical and psychosocial symptoms. The aims of treatment are to prevent the patient from rebleeding and to prevent secondary neurological damage. Whereas in former times, clipping of the aneurysm was often delayed for days or weeks, early operative intervention is the rule today, if the patient is not moribund and if there is no significant cerebral oedema. The anaesthetist can support the neurosurgeon with a spectrum of different methods of anaesthesia and monitoring, individually tailored to the needs of the patient. Most important, however, is a stable haemodynamic status, stable and normal intracranial pressure and a sufficient cerebral perfusion pressure. Vasospasm is still the main problem, as is early rebleeding. To treat this, nimodipine is the drug of choice combined with volume therapy, a slightly elevated cardiac output and a modestly elevated blood pressure.