Subarachnoid hemorrhage: a review

Interference of apoptosis in the pathophysiology of subarachnoid hemorrhage

Programmed cell death is crucial for the correct development of the organism and the clearance of harmful cells like tumor cells or autoreactive immune cells. Apoptosis is initiated by the activation of cell death receptors and in most cases it is associated with the activation of the cysteine proteases, which lead to apoptotic cell death. Cells shrink, chromatin clumps and forms a large, sharply demarcated, crescent-shaped or round mass; the nucleus condenses, apoptotic bodies are formed and eventually dead cells are engulfed by a neighboring cell or cleared by phagocytosis. The authors have summarized the most important data concerning apoptosis in subarachnoid hemorrhage that have been issued in the medical literature in the last 20 years.

Apoptotic mechanisms for neuronal cells in early brain injury after subarachnoid hemorrhage

OBJECTS

The major causes of death and disability in subarachnoid hemorrhage (SAH) may be early brain injury (EBI) and cerebral vasospasm. Although cerebral vasospasm has been studied and treated by a lot of drugs, the outcome is not improved even if vasospasm is reversed. Based on these data, EBI is considered a primary target for future research, and apoptosis may be involved in EBI after experimental SAH.

METHODS

We reviewed the published literature about the relationship between SAH induced EBI and apoptosis in PubMed.

RESULT

Most available information can be obtained from the endovascular filament perforation animal model. After onset of SAH, intracranial pressure is increased and then cerebral blood flow is reduced. Many factors are involved in the mechanism of apoptotic cell death in EBI after SAH. In the neuronal cells, both intrinsic and extrinsic pathways of apoptosis can occur. Some antiapoptotic drugs were studied and demonstrated a protective effect against EBI after SAH. However, apoptosis in EBI after SAH has been little studied and further studies will provide us more beneficial findings.

CONCLUSIONS

The study of apoptosis in EBI after experimental SAH may give us new therapies for SAH.

Molecular mechanisms of early brain injury after subarachnoid hemorrhage

OBJECTIVES

Increasing body of experimental and clinical data indicates that early brain injury after initial bleeding largely contributes to unfavorable outcome after subarachnoid hemorrhage (SAH). This review presents molecular mechanisms underlying brain injury at its early stages after SAH.

METHODS

PubMed was searched using term 'subarachnoid hemorrhage' and key words referring to molecular and cellular pathomechanisms of SAH-induced early brain injury.

RESULTS

The authors reviewed intracranial phenomena and molecular agents that contribute to the early development of pathological sequelae of SAH in cerebral and vascular tissues, including cerebral ischemia and its interactions with injurious blood components, blood-brain barrier disruption, brain edema and apoptosis.

DISCUSSION

It is believed that detailed knowledge of molecular signaling pathways after SAH will serve to improve therapeutic interventions. The most promising approach is the protection of neurovascular unit including anti-apoptosis therapy.

Sensitivity of new-generation computed tomography in subarachnoid hemorrhage

OBJECTIVE

To determine the sensitivity of the initial new-generation CT (NGCT) scan interpretation for detection of acute nontraumatic subarachnoid hemorrhage (SAH) and to decide whether lumbar puncture (LP) should follow a "normal" NGCT scan.

METHODS

A retrospective chart review was performed of patients admitted between March 1988 and July 1994 with proven SAH. Exclusion criteria were age < 2 years, diagnosis other than acute SAH, history of head trauma within 24 hours before symptom onset, NGCT scan not done before diagnosis, and records not available. Patients were placed into two groups: symptom duration < 24 hours (group 1) and > 24 hours (group 2) prior to CT scan. The resolution of each NGCT scanner was recorded. An NGCT scanner was defined as a third-generation scanner or more recent.

RESULTS

Of 349 SAH patients, 181 met inclusion criteria. The sensitivity of NGCT scans for SAH was 93.1% for the group 1 patients (n = 144) and 83.8% for the group 2 patients (n = 37). The overall sensitivity was 91.2%. All the patients who had SAH not detected by NGCT scans were diagnosed by LP. There was no significant relationship between NGCT scanner resolution and sensitivity for SAH.

CONCLUSION

Initial interpretation of NGCT scans to detect SAH does not approach 100% sensitivity. A "normal" NGCT scan does not reliably exclude the need for LP in patients who have symptoms suggestive of SAH.

Subarachnoid hemorrhage: an unusual presentation of shock

A 42-year-old woman became profoundly hypotensive shortly after arriving at our emergency medical center after a seizure. The patient's blood pressure did not respond to aggressive fluid resuscitation, administration of inotropic agents, vasopressors, or corticosteroids. After a thorough search for the cause of shock, she was found to have a subarachnoid hemorrhage (SAH). Hypotension is a rare occurrence in SAH. Several mechanisms of SAH are reviewed in this report and are invoked to explain this patient's lack of response to the standard therapies for hypotension. Emergency physicians should consider SAH in the differential diagnosis of refractory shock in patients who present with neurologic abnormalities.

Cognitive performance following rupture and repair of intracranial aneurysm

Modern microsurgical techniques enable most survivors of subarachnoid haemorrhage following ruptured intracranial aneurysm to make a good functional recovery. Nevertheless, it has been suggested that such patients suffer from a persistent disturbance of cognitive function. When tested 6 weeks after their discharge from the neurosurgical unit, patients from a consecutive series of 76 cases of aneurysmal subarachnoid haemorrhage demonstrated a moderate impairment of performance across a broad range of cognitive tasks. This was more pronounced in the case of patients who had suffered generalized postoperative vasospasm, but was unrelated to the site of the ruptured aneurysm. However, when patients were tested 6 months after discharge, the only consistent deficits were in the speed of retrieval of verbal items from semantic memory, and there was little evidence of any generalized cognitive impairment.

Recognition of subarachnoid hemorrhage

The medical records of 109 patients who presented to the emergency department during a five-year period with proven nontraumatic, spontaneous subarachnoid hemorrhage (SAH) were retrospectively reviewed. The clinical presentation, diagnostic modalities used, and accuracy of diagnosis by emergency physicians were analyzed. The most common historical features were headache (81 patients, or 74%), nausea or vomiting (85 patients, or 77%), and loss of consciousness (58 patients, or 53%). Nonexertional activities preceding SAH were more frequent than exertional events (57% vs 21%). Neurologic findings were present in 70 patients (64%) and consisted primarily of altered levels of consciousness. Thirty-eight patients (35%) had nuchal rigidity. Ninety-six emergency cranial computed tomography scans were performed, of which 91 were diagnostic for SAH (sensitivity, 95%). Lumbar puncture was performed on two patients with normal computed tomography scans and revealed bloody spinal fluid. The overall diagnostic accuracy by emergency physicians was 85%. The correct diagnosis was delayed in 16 patients (15%), the majority of whom had headaches and normal neurologic examinations. Atypical symptoms, the warning leak syndrome, and the need for prompt diagnosis and therapy are reviewed.