Headache in patients with chronic subdural hematoma: analysis in 1080 patients.

Headache is a major symptom in chronic subdural hematoma (CSDH) patients. However, some CSDH patients do not complain headache although the hematoma is thick with definite midline shift. This clinical study was performed to identify the mechanism of headache in CSDH patients. We compiled clinical data of 1080 surgically treated CSDH patients (711 males and 369 females), and in 54 cases, the pressure of hematoma was measured during burr hole surgery using a glass-stick manometer. Headache was recognized in 22.6% of patients, while nausea or vomit suggesting increased intracranial pressure was detected in only 3.0%. Ophthalmological examination was performed in 238 patients, and papilledema was identified in only one patient (0.4%). The mean age of patients with headache (59.8 ± 16.9 years) was significantly younger than that of those without (75.7 ± 11.2 years) (P < 0.01). In 54 cases, the mean hematoma pressure was not significantly different between patients with (17.1 ± 6.2 mmH2O) and without (18.4 ± 7.2 mmH2O) headache (P > 0.10). Hematoma thickness was significantly greater in patients without headache (P < 0.01), but the ratio of midline shift to hematoma thickness was significantly greater in patients with headache (P < 0.01). In our results, the status of increased intracranial pressure was rare in CSDH patients, and high hematoma pressure was not a cause of headache. Midline shift was the most influenced factor for headache in our study, and based on the results, the authors consider that the potential cause of headache in CSDH might be stretching or twisting of the pain-sensitive meninges and meningeal arteries or veins.

Clipping Surgery for Unruptured Middle Cerebral Artery Aneurysms.

Clipping surgeries for 139 consecutive unruptured middle cerebral aneurysms were performed between April 1991 and March 2014. Left hemiparesis occurred in one case (0.7 %). Transient symptoms arose in six patients due to perforator injury, arterial branch occlusion, damage to the venous system, or chronic subdural hematoma. Neither mortality nor decline in cognitive function was noted in this study. Clipping surgery for unruptured middle cerebral artery aneurysms can be done with minimal morbidity. However, meticulous management during the perioperative period as well as the use of modern technologies during the surgery, such as MEP monitoring and ICG videoangiography, are needed for safe and secure clipping surgery.

Distal basilar artery aneurysms: conditions for safe and secure clipping.

In general, vertebro-basilar aneurysms are good indications for endovascular treatment. However, basilar artery (BA) bifurcation aneurysms, BA-superior cerebellar artery (SCA) aneurysms, and sometimes mid-basilar aneurysms are also good indications for clipping. In this paper, conditions for safe and secure clipping for distal basilar aneurysms are discussed.There are several tips for the clipping of distal BA aneurysms. Among them, the following are very important: patency of the perforators, posterior cerebral artery (P1), and SCA must always be maintained. Several modalities including micro-Doppler ultrasonography and indocyanine green video-angiography (ICGVA) should be used to confirm the patency of these vessels. Each confirmation of patency of the vessels after clipping must be compared to those from before the clipping. Intra-operative digital subtraction angiography (DSA) is needed for large or giant aneurysms.

Relationship between time from ambulance call to arrival at emergency center and level of consciousness at admission in severe stroke patients.

INTRODUCTION: Timely access to acute medical treatment can be critical for patients suffering from severe stroke. Little information is available about the impact of prehospital delays on the clinical conditions of stroke patients, but it is possible that prehospital delays lead to neurological deterioration. The aim of this study was to examine the impact of prehospital delays related to emergency medical services on the level of consciousness at admission in patients with severe stroke. METHODS: This retrospective study assessed 712 consecutive patients diagnosed with cerebrovascular diseases who were admitted to an intensive care unit in Tokyo, Japan, from April 1998 through March 2008. Data, including the time from the call to the ambulance service to the arrival of the ambulance at the patient location (on-scene), and the time from the arrival of the ambulance on-scene to its arrival at the emergency center were obtained. The following demographic and clinical information also were obtained from medical records: sex, age, and Glasgow Coma Scale (GCS) score at admission. RESULTS: The mean time from ambulance call to arrival on-scene was 7 (SD=3) minutes, and the mean time from ambulance call to arrival at the center was 37 (SD=8) minutes. A logistic regression model for predicting GCS scores of 3 and 4 at admission was produced. After adjusting for sex, age, and time from arrival on-scene to arrival at the center, a longer call-to-on-scene time was significantly associated with poor GCS scores (OR = 1.056/min; 95% confidence interval, [CI] = 1.008-1.107). After adjusting for sex and age, a longer call-to-arrival at the center time also was significantly associated with poor GCS scores (OR = 1.020; 95% CI = 1.002-1.038). CONCLUSIONS: Prehospital delays were significantly associated with decreased levels of consciousness at admission in patients suffering from a stroke. As level of consciousness is the strongest predictor of outcome, reducing prehospital delays may be necessary to improve the outcomes in patients with severe stroke.

[A case of infected subdural hematoma accompanied by cerebral infarction].

Infected subdural hematoma(ISH)is a rare disease caused by hematogenous infection of a preexisting subdural hematoma. We report a rare case of ISH accompanied by cerebral infarction. A 76-year-old man who had suffered a closed head injury 3 months before presented fever, headache and left hemiparesis during the medical treatment of acute cholangitis and obstructive jaundice with pancreatic cancer at the department of surgical gastroenterology. At the consultation, computed tomography(CT)scan indicated right chronic subdural hematoma. We performed a burr hole opening surgery on the same day. Abscess and hematoma was aspirated from the subdural space, and methicillin-resistant Staphylococcus aureus(MRSA)was detected in this specimen. Thus the diagnosis of the infected subdural hematoma was confirmed. However, despite the antibiotics therapy, follow-up CT showed a low-density area close to the residual abscess, which suggested cerebral infarction. Cerebral angiography showed a vasospasm at the cortical segment of the right middle cerebral artery near the residual abscess. Eventually we carried out a small craniotomy to evacuate the abscess. Our case showed that prompt surgical treatment is required in case of ISH and the whole hematoma and abscess should be removed as soon as possible with an image diagnosis and an additional surgical operation.

[Characteristics and treatment of dural and perimedullary arteriovenous fistula at the craniocervical junction presenting with subarachnoid hemorrhage].

Dural and perimedullary arteriovenous fistula (AVF) at the craniocervical junction tend to cause subarachnoid hemorrhage (SAH). However, their natural history and clinical manifestations still remain to be elucidated. From 2003 to 2009, we encountered 5 cases of dural and perimedullary AVF presented with SAH. They were all male, ranging in age from 53 to 85 year-old (mean: 68 year-old). Rebleeding occurred in 1 patient on day 11. Outcome estimated by modified Rankin Scale did not change remarkably from 2.6 on admission to 2.4 at 3 months later on average. Cerebral angiography and 3D-CT angiography disclosed feeders originating from radicular or intracranial vertebral arteries which drained into the epidural venous plexus or spinal meningeal veins. One patient died of systemic complication during his clinical course. Thus we performed open surgery in the remaining 4 patients. Of these, we failed to occlude feeders completely in the initial surgery without intraoperative digital subtraction angiography (DSA) in 2 patients. Following this treatment we performed coil embolization and repeated open surgery with the aid of intraoperative DSA, respectively. In 1 patient out of the remaining 2 patients, we utilized intraoperative DSA to confirm complete disappearance of AVF composed of multiple feeders. These observations show that SAH caused by dural and perimedullary AVF at the craniocervical junction should be mainly treated by open surgery with the aid of intraoperative DSA in order to accomplish obliteration of the feeders because, otherwise, we might fail to confirm complete disappearance of AVF.

Surgical procedure and results of cisternal washing therapy for the prevention of cerebral vasospasm following SAH.

In 1994, we started cisternal washing therapy (CWT) using urokinase combined with head-shaking method in order to prevent cerebral vasospasm. In this paper, we showed the surgical procedure for CWT and reported the effect of this therapy in preventing vasospasm following SAH. A total of 332 consecutive cases with Fisher group 3 SAH since 1988 were analyzed. Of these patients, 118 cases (56 cases before 1994 and 62 cases after 1994) had not CWT, and, 214 cases after 1994 had this therapy. All of these patients had clipping surgery within 3 days following SAH, and had postoperative management both with normovolemia and normal to mild hypertension. In these two groups, the incidence of symptomatic vasospasm (transiently symptomatic vasospasm without infarction), cerebral infarction due to vasospasm on CT, and mortality and morbidity (M&M) due to vasospasm were analyzed. In the group without CWT, the incidences of symptomatic vasospasm, cerebral infarction on CT, and M&M due to vasospasm were 4.2%, 28.8%, and 17.8%, respectively. On the other hand, in the group with CWT, they were 3.7%, 6.5%, and 2.8%, respectively. In the patients with CWT, the incidence of cerebral infarction on CT due to vasospasm and M&M due to vasospasm were significantly (p < 0.05) decreased. CWT was effective in preventing cerebral vasospasm.

Importance of the initial grade of subarachnoid hemorrhage in the patients with the age of 80 years and older from a single center analysis.

In the developed countries, especially Japan, elderly population is rapidly increasing, but outcomes of elderly patients with the age of 80 years and older suffering from subarachnoid hemorrhage (SAH) remain still unclear. We retrospectively reviewed the medical records of nontraumatic SAH patients aged 80 years and older, who were hospitalized in a single center between 1998 and 2009. There were 28 patients (80-90 years old and 75% female), representing 5.9% of all non-traumatic SAHs (n = 474). Of those, 16 patients received an intervention (ten clipping and six endovascular coiling) and the remaining 12 patients were managed conservatively. The median survival time of intervention group was 110 days and that of conservative group 49 days (p = 0.12, log rank analysis). Cox's proportional hazards model yielded two variables, the Japan Coma Scale (JCS) grade on admission ( hazard ratio: 2.93 [p = 0.009]) and conservative treatment (hazard ratio: 2.14 [p = 0.054]). In the outcome of the modified Rankin Scale between these two groups, logistic regression analysis had significant variable; the JCS grade on admission (odds ratio: 280, [p = 0.020]). In the elderly patients with good initial clinical condition, an acute intervention may have good outcome.

Blood pressure management in acute intracerebral haemorrhage: low blood pressure and early neurological deterioration.

OBJECT: Lowering the blood pressure (BP) of patients with intracerebral haemorrhage (ICH) can prevent haematoma enlargement but may also promote secondary infarction in areas adjacent to the haematoma, which can lead to neurological deterioration. Little is known about the effects of low BP on early neurological deterioration (END). We conducted a retrospective study to determine whether low BP after admission was associated with END in patients with acute ICH. METHODS: We investigated 100 consecutive patients diagnosed with spontaneous ICH. We obtained data on minimum systolic blood pressure (SBP) in the 24 h after admission and related factors and assessed END in this time window. RESULTS: END occurred in 38 patients. The frequencies of END by minimum SBP quartile were 52% ( 130 mmHg). A logistic regression model for predicting END was developed using SBP at admission, Glasgow Coma Scale at admission, haematoma volume, minimum SBP, and squared minimum SBP. A U-shaped relationship between minimum SBP and END (p = 0.02) was observed, with the lowest risk for END at a minimum SBP of 123 mmHg. The curve was nearly flat for a minimum SBP of 115-130 mmHg, indicating that the risk of END is relatively low across this range of minimum SBPs. CONCLUSIONS: Our findings suggest that a minimum SBP of approximately 120-125 mmHg after admission is associated with a beneficial impact on a reduced risk of END.

Association between symptom duration and cerebrospinal fluid pressure, protein concentration, and number of cells in patients with intracranial hypotension.

We sought to investigate the association between symptom duration and cerebrospinal fluid (CSF) pressure, protein concentration, and cell counts in patients with intracranial hypotension, in addition to examining differences between spontaneous and post-traumatic types. We investigated 115 consecutive patients with CSF leaks, demonstrated by radionuclide cisternography. In patients with spontaneous CSF leaks, a significant decrease in pressure and increase in protein concentration and number of cells were observed in patients with a symptom duration of 3 months. Symptom duration was not associated with those CSF parameters in patients with post-traumatic CSF leaks.

L-PDMP improves glucosylceramide synthesis and behavior in rats with focal ischemia.

BACKGROUND: It has been shown that exogenic administration of glycosphingolipids (GSLs) induces outgrowth of neurites from cultured nerve cells. Furthermore, the activator of glucosylceramide synthase, L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (L-PDMP), is thought to exhibit stimulatory effects on both the biosynthesis and neurotrophic actions of GSL in the same culture system. To investigate the effect of GSLs on focal cerebral ischemia in vivo, L-PDMP was injected into the intraperitoneal space of rats during the chronic phase following permanent occlusion of the left middle cerebral artery (MCA) and thereafter, the levels of GSLs and their effects on behavioral changes were examined Methods: The levels of cerebrosides, sphingomyelin (SM) and ceramide in the ischemic cortex were measured by gas-liquid chromatography (GLC) after separation by high-performance thin-layer chromatography, using the internal standards N-heptadecanoyl-D-cerebroside, N-heptadecanoyl-D-sphingomyelin and N-heptadecanoyl-D-sphingosine, respectively. To determine the sugar components of the cerebrosides, the trimethylsilylated derivatives of their methylglycosides after methanolysis were analysed directly by GLC. RESULTS: The L-PDMP treatment induced a 2.4-fold increase in glucosylceramide, the precursor of gangliosides, but no changes were evident in the levels of SM and ceramide in the ischemic cerebral cortex. The ischemic rats treated with L-PDMP showed improved re-acquisition of memory and learning in the Morris water maze task. CONCLUSION: These results suggest that the pharmacological effects of L-PDMP include significant facilitation of glucosylceramide biosynthesis and improvement of neural function.

Symptom predictors of cerebrospinal fluid leaks.

BACKGROUND: Spinal cerebrospinal fluid (CSF) leaks, which are considered a cause of intracranial hypotension, generally do not cause any local symptoms. Although symptoms are key elements for further evaluation, few studies have examined symptom predictors of intracranial hypotension. The aim of this study was to determine what symptoms are predictors of CSF leaks in patients suspected of intracranial hypotension. METHODS: We performed radionuclide cisternography in 207 consecutive patients suspected of intracranial hypotension. Intracranial hypotension was suspected when a patient had a history of minor trauma and complained about uncontrolled headache, cranial nerve dysfunction, autonomic dysfunction, or higher brain dysfunction. The leakage of CSF was defined as direct signs of tracer leak into the spinal epidural space or early accumulation of the tracer in the urinary bladder. We obtained information on 16 symptoms commonly reported in previous studies. RESULTS: CSF leaks were observed in 154 cases (74%). Back pain, limb pain, and limb numbness were inversely associated with CSF leaks (p = 0.042, p = 0.045, and p = 0.006, respectively). In logistic regression analysis, diplopia was a positive predictor of CSF leaks (odds ratio [OR], 6.53; 95% confidence interval [CI], 1.49 to 28.51), whereas limb numbness was a negative predictor (OR, 0.38; 95% CI, 0.17 to 0.84). Of the 21 patients in whom diplopia was present and limb numbness was absent, 20 had CSF leaks (specificity, 98%; positive predictive value, 95%). CONCLUSION: Some symptoms may be helpful in the diagnosis of CSF leaks in patients suspected of intracranial hypotension.

Preservation of the lesser occipital nerve during microvascular decompression for hemifacial spasm. Technical note.

The authors report on their technique for preserving the lesser occipital nerve (LON) during lateral suboccipital craniotomy. In their technique, the LON, which runs along the surface of or just beneath the sternocleidomastoid muscle, is identified and preserved. Lesser occipital nerve preservation using their technique was attempted in 25 patients who underwent microvascular decompression for hemifacial spasm. The LON was successfully preserved in 16 of these patients, was impossible to preserve in two patients, and could not be identified in seven patients. Among the patients in whom LON preservation was successful, 87.5% were free of sensory disturbance 6 months after surgery, whereas both patients in whom the LON could not be preserved complained of sensory disturbances in the occipital area and the posterior part of the auricula. Fifty-seven percent of the patients whose LON could not be identified complained of sensory disturbance. Thus, this technique for preserving the LON reduces the incidence of sensory disturbance in the occipital region after suboccipital craniotomy for microvascular decompression for hemifacial spasm.

Effectiveness of interferon-beta and temozolomide combination therapy against temozolomide-refractory recurrent anaplastic astrocytoma.

BACKGROUND: Malignant gliomas recur even after extensive surgery and chemo-radiotherapy. Although a relatively novel chemotherapeutic agent, temozolomide (TMZ), has demonstrated promising activity against recurrent glioma, the effects last only a few months and drug resistance develops thereafter in most cases. Induction of O6-methylguanine-DNA methyltransferase (MGMT) in tumors is considered to be responsible for resistance to TMZ. Interferon-beta has been reported to suppress MGMT in an experimental glioma model. Here we report a patient with TMZ-refractory anaplastic astrocytoma (AA) who was treated successfully with a combination of interferon-beta and TMZ. CASE PRESENTATION: A patient with recurrent AA after radiation-chemotherapy and stereotactic radiotherapy was treated with TMZ. After 6 cycles, the tumor became refractory to TMZ, and the patient was treated with interferon-beta at 3 x 106 international units/body, followed by 5 consecutive days of 200 mg/m2 TMZ in cycles of 28 days. After the second cycle the tumor decreased in size by 50% (PR). The tumor showed further shrinkage after 8 months and the patient's KPS improved from 70% to 100%. The immunohistochemical study of the initial tumor specimen confirmed positive MGMT protein expression. CONCLUSION: It is considered that interferon-beta pre-administration increased the TMZ sensitivity of the glioma, which had been refractory to TMZ monotherapy.

Pituitary cyst presenting with hyponatremia and increased secretion of brain natriuretic peptide. Case report.

In most cases of pituitary cyst there are no clinical symptoms and the lesions are found incidentally. The authors report the case of a 60-year-old man with a pituitary cyst causing visual disturbance and hyponatremia. The patient presented with appetite loss and general fatigue. On admission, blood workup showed severe hyponatremia (112 mEq/L), and bitemporal hemianopsia was observed on neurological examination. Magnetic resonance imaging revealed an intra- and suprasellar region cystic mass extending to the frontal base and hypothalamic area. The serum level of brain natriuretic peptide (BNP) was elevated (92 pg/ml) with polyuria and excessive Na excretion. Transsphenoidal surgery was performed to drain the cyst. The cyst wall was partially excised and the cystic fluid was aspirated. The secretion of BNP normalized postoperatively, and the hyponatremia and visual symptoms resolved. Histological examination, including an electron microscopy study, confirmed the diagnosis of a simple cyst. This appears to be the first reported case of a pituitary simple cyst associated with hyponatremia and an elevated BNP level.

Pituitary apoplexy as a consequence of lymphocytic adenohypophysitis in a pregnant woman: a case report.

OBJECTIVE AND IMPORTANCE: A patient with pituitary apoplexy resulting from lymphocytic adenohypophysitis, which caused visual disturbance during pregnancy, is described. This is the first report of such case. CLINICAL PRESENTATION: A 23-year-old primigravida in her 25th week of gestation experienced headache and bitemporal hemianopsia of sudden onset. Magnetic resonance imaging (MRI) revealed a large pituitary mass with intratumoral hemorrhage. Although conservative treatment with intravenous glycerol improved the symptoms partially, the visual symptoms worsened again 6 weeks later. After delivering a girl by scheduled caesarean section her visual symptoms improved. Despite the symptomatic improvement, MRI showed the chiasmatic compression by the enlarged pituitary gland had not changed. Therefore, trans-sphenoidal surgery to decompress the chiasm was performed. Necrotic tissue was seen exuding behind the enlarged pituitary gland and adenohypophysitis with bleeding (apoplexy) was diagnosed histologically. After follow-up for 40 months, she was doing well without any visual or neurological deficits. CONCLUSION: Although relatively rare, pituitary apoplexy as a consequence of lymphocytic adenohypophysitis should be borne in mind when a pregnant woman presents with headache and visual disturbance of sudden onset.

Blood pressure management in acute intracerebral hemorrhage: relationship between elevated blood pressure and hematoma enlargement.

BACKGROUND AND PURPOSE: The association between elevated blood pressure (BP) and hematoma enlargement in acute intracerebral hemorrhage (ICH) has not been clarified. We investigated the association between maximum systolic BP (SBP) and hematoma enlargement, measuring SBP between a baseline and a second CT scan in patients with hypertensive ICH. METHODS: We assessed 76 consecutive patients with hypertensive ICH retrospectively. We usually attempted to lower SBP below targets of 140, 150, or 160 mm Hg. Recordings of serial BP from admission until the second CT scan were assessed. A neuroradiologist, who was not informed of the aim of this study, reviewed CT films. Hematoma enlargement was defined as an increase in volume of > or =140% or 12.5 cm3. RESULTS: Hematoma enlargement occurred in 16 patients. Maximum SBP was significantly associated with hematoma enlargement (P=0.0074). A logistic regression model for predicting hematoma enlargement was constructed with the use of maximum SBP, hematoma volume, and Glasgow Coma Scale score at admission. After adjustment for these factors, maximum SBP was independently associated with hematoma enlargement (odds ratio per mm Hg, 1.04; 95% CI, 1.01 to 1.07). Target SBPs of > or =160 mm Hg were significantly associated with hematoma enlargement compared with those of < or =150 mm Hg (P=0.025). CONCLUSIONS: Our findings suggest that elevated BP increases the risk of hematoma enlargement. Efforts to lower SBP below 150 mm Hg may prevent this risk.

Differences in the extent of primary ischemic damage between middle cerebral artery coagulation and intraluminal occlusion models.

The authors studied the differences between heat-shock/stress protein 70 (hsp70) gene expression and protein synthesis in the unilateral middle cerebral artery (MCA) microsurgical direct occlusion (Tamura's) model and the unilateral intraluminal occlusion model. In Tamura's model, expression of hsp70 mRNA and HSP70 protein and decreased protein synthesis were detected in the ischemic areas, including the ipsilateral cortex and caudate. These phenomena, however, were not observed in the areas outside the MCA territory, including the ipsilateral thalamus, hippocampus, and substantia nigra. These results were consistent among the experimental rats. In the intraluminal occlusion model, however, induction of both hsp70 mRNA and HSP70 protein and impairment of protein synthesis were noted in the areas outside the MCA territory, including the ipsilateral thalamus, hypothalamus, hippocampus, and substantia nigra, as well as in the MCA territory, including the ipsilateral cortex and caudate. These results were not consistent among the experimental rats. These different results might be due to widespread damage resulting from internal carotid artery (ICA) occlusion in the intraluminal occlusion model. Accordingly, the authors suggest that this model be called an ICA occlusion model, rather than a pure MCA occlusion model.

In vivo influence of ceramide accumulation induced by treatment with a glucosylceramide synthase inhibitor on ischemic neuronal cell death.

It has been shown that exogenous ceramide induces delayed neuronal death (DND) of cultured hippocampal neurons. To evaluate the role of endogenous ceramide in ischemic DND, the glucosylceramide synthase inhibitor, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), was used to generate ceramide in gerbil hippocampi in vivo. The trimethylsilylated derivatives of ceramide were analyzed directly by gas chromatography mass spectrometry, after separation with high-performance thin-layer chromatography. The ceramide compositions in vehicle hippocampus consisted mainly of C18:0 fatty acyl sphingosine (87.9%), with C16:0 and C20:0 ceramides being minor components (7.1% and 5.1%, respectively). Ceramide level in the hippocampi from gerbils subjected to D-PDMP treatment was 1.5-fold higher than those from vehicle-treated gerbils. In spite of the accumulation of ceramide observed in the D-PDMP group, the histological studies did not reveal any ischemic neuronal death in hippocampal CA1 neurons with the gerbils that had been subjected to a sham operation (2-min sublethal ischemia). These results suggest that the ceramide accumulation induced by blocking the de novo synthesis of glucosylceramide with D-PDMP may be independent of the metabolic pathway underlying ischemic DND.

Natural hypothermia immediately after transient global cerebral ischemia induced by spontaneous subarachnoid hemorrhage.

OBJECT: Spontaneous subarachnoid hemorrhage (SAH) has an aspect of graded transient global cerebral ischemia. The purpose of the present study was the documentation of sequential changes in body temperature immediately after SAH-induced transient global cerebral ischemia in humans. METHODS: Patients admitted within 12 hours after the initial onset of SAH were examined retrospectively (426 patients). Patients with unruptured cerebral aneurysms served as a control group (73 patients). Body temperature measured at the axilla on admission was analyzed. The grade of SAH was established according to the Glasgow Coma Scale (GCS): Grade I, GCS Score 15; Grade II, GCS Score 11 to 14; Grade III, GCS Score 8 to 10; Grade IV, GCS Score 4 to 7; and Grade V, GCS Score 3. The mean body temperature of patients in the control group was 36.49 +/- 0.45 degrees C (mean +/- standard deviation). The mean body temperature of patients in the SAH group who had been admitted within 4 hours of onset for Grades I to V were significantly different (p < 0.001, analysis of variance [ANOVA]): 36.26 +/- 0.7 degrees C, 59 patients; 35.98 +/-0.85 degrees C, 73 patients; 35.52 +/- 0.79 degrees C, 25 patients; 35.9 +/- 1.09 degrees C, 108 patients; and 35.56 +/- 1.14 degrees C, 73 patients, respectively. These values were significantly lower than those in control volunteers, except for patients with Grade I SAH. The reduction in body temperature was unrelated to the location of the cerebral aneurysm and was not the product of circadian rhythm. The temperatures of patients in the SAH group who were admitted beyond 4 hours after onset for each grade were significantly different (p < 0.01, ANOVA): 36.8 +/- 0.91 degrees C, 36 patients; 36.74 +/- 0.68 degrees C, 31 patients; 36.73 +/- 0.38 degrees C, three patients; 37.41 +/- 1.37 degrees C, 17 patients; and 38.9 degrees C, one patient, respectively. These values were significantly higher than those in patients admitted within 4 hours of SAH onset for all grades except Grade V, and significantly higher than control values in patients with Grades I and IV SAH. CONCLUSIONS: These results indicate that body temperature falls and then rises immediately after the SAH-induced transient global cerebral ischemia without cardiac arrest in humans. The reduction in temperature may be a natural cerebral protection mechanism that is activated shortly after ischemic insult.