Supratentorial intracerebral hemorrhage following posterior fossa surgery

Early postoperative acetylsalicylic acid administration does not increase the risk of postoperative intracranial bleeding in patients with spontaneous intracerebral hemorrhage

Administration of acetylsalicylic acid (ASA) at early stage after surgery for spontaneous intracerebral hemorrhage (SICH) may increase the risk of postoperative intracranial bleeding (PIB), because of potential inhibition of platelet function. This study aimed to investigate whether early ASA administration after surgery was related to increased risk of PIB. This retrospective study enrolled SICH patients receiving surgery from September 2019 to December 2022 in seven medical institution. Based on postoperative ASA administration, patients who continuously received ASA more than three days within seven days post-surgery were identified as ASA users, otherwise as non-ASA users. The primary outcome was symptomatic PIB events within seven days after surgery. Incidence of PIB was compared between ASA users and non-ASA users using survival analysis. This study included 744 appropriate patients from 794 SICH patients. PIB occurred in 42 patients. Survival analysis showed no statistical difference between ASA users and non-ASA users in incidence of PIB (P = 0.900). Multivariate Cox analysis demonstrated current smoker (hazard ratio [HR], 2.50, 95%CI, 1.33-4.71, P = 0.005), dyslipidemia (HR = 3.03; 95%CI, 1.31-6.99; P = 0.010) and pre-hemorrhagic antiplatelet therapy (HR = 3.05; 95% CI, 1.64-5.68; P < 0.001) were associated with PIB. Subgroup analysis manifested no significant difference in incidence of PIB between ASA users and non-ASA users after controlling the effect from factors of PIB (i.e., sex, age, current smoker, regular drinker, dyslipidemia, pre-hemorrhagic antiplatelet therapy and hematoma location). This study revealed that early ASA administration to SICH patients after surgery was not related to increased risk of PIB.

Remote supratentorial intraparenchymal bleed after posterior fossa surgery: A rare occurrence

Background

Intraparenchymal hemorrhage at the operative site is one of the major complications of brain surgery. It is unusual to occur at a site remote from the operative site, but when it happens, it may cause significant morbidity and mortality.

Case Description

We report the case of a 27-year-old male who presented with complaints of paresthesias over the left side of his face and decreased hearing from the left ear for two years. His radiology was suggestive of a large left cerebellopontine angle epidermoid cyst. The patient underwent left retro mastoid suboccipital craniotomy and near-total excision of the epidermoid cyst. The immediate postoperative non-contrast computed tomography scan of the brain was suggestive of no hematoma at the operated site but a remote left parafalcine frontoparietal intraparenchymal bleed, which was managed conservatively. At two months follow-up, he had no neuro deficits, and magnetic resonance imaging of the brain was suggestive of near-total excision of the epidermoid cyst with resolving left parafalcine frontoparietal bleed.

Conclusion

We report this case due to the unique case observation of an intracranial bleed at a remote site rather than at the operated site.

Supratentorial Intracerebral Hematoma as a Rare Complication of Posterior Fossa Surgery in Prone Position: A Case Report with Review of Literature

Supratentorial intracerebral hematoma is a rare complication after posterior fossa tumor surgery in prone positioning. Although rare, its occurrence may cause significant impact on survival of the patient. We had described this rare complication and their possible pathophysiology in this report. A 52-year-old male with fourth ventricle epidermoid tumor with noncommunicative hydrocephalus was presented to us in drowsy condition in emergency department. Right-sided medium pressure ventriculoperitoneal surgery was performed in emergency. After shunt surgery patient become conscious and oriented. Total excision of tumor was done via suboccipital craniotomy in prone positioning after preanesthesia fitness. Patient extubated from anesthesia and was conscious but after 2 hours patient condition deteriorated. Patient was intubated again and taken on ventilatory support. Postoperative plain computed tomography brain showed total excision of tumor with left temporal lobe hematoma. Patient was managed conservatively and his condition improved in 3 weeks' periods. Supratentorial intracerebral hematoma after posterior fossa surgery in prone positioning is a rare complication. Despite the rarity of this complication, it is still challenging as it may lead to significant morbidity and mortality.

Supratentorial intracerebral hemorrhage as a complication of infratentorial tumor removal: A case report

•

Intracerebral hemorrhage (ICH) at the operative site is one of the major complications of brain surgery.

•

Imaging modalities like CT scan can easily discover and diagnose intracerebral hemorrhage.

•

When intracerebral hemorrhage occurs it may lead to deadly complications and best to be surgically evacuated.

•

Supratentorial intracerebral hemorrhage rarely complicates surgeries of infratentorial tumors.

Introduction

In this article we report a case of supratentorial intracerebral hemorrhage developed following days of posterior fossa surgical tumor removal.

Presentation of case

Nine years old female was diagnosed as a patient with posterior fossa tumor and hydrocephalus, endoscopic third ventriculostomy was done and the tumor was resected using craniectomy and trans-vermian approach. The patient was discharged home on post-operative day 10 but re-admitted on day 35 with a new insult of right temporo-parieto-occipital intracerebral hematoma which was evacuated successfully urgently and the patient had got better on day 4, but then she developed right hemispheric ischemia and died.

Discussion

Although this complication is rare, it carries significant morbidity and mortality, literatures discussing this condition are scanty and no obvious cause was mentioned.

Conclusion

We recommend putting in mind such a complication in case of any post-operative neurological deterioration occurs to a patient with surgically excised posterior fossa lesion.

Postoperative Hematoma Requiring Recraniotomy in 1149 Consecutive Patients With Intracranial Tumors

BACKGROUND

The reported 30-day mortality rate after brain tumor surgery is 2.2% to 2.9%, with a postoperative hematoma (POH) as the most frequent cause of death.

OBJECTIVE

To investigate the risk factors for a POH requiring a recraniotomy after brain tumor surgery in a large, contemporary, single-institution consecutive series.

METHODS

We included 1149 patients who underwent surgery for intracranial tumors at the Tokushima University Hospital from 1997 to 2014. The patient charts were retrospectively studied from our prospectively collected database. We analyzed the risk factors, type of hemorrhage, time to reoperation, and outcomes.

RESULTS

The incidence of a POH requiring a recraniotomy was 2.09%. Among the patients with a POH requiring a recraniotomy, 12.5% died within 30 days of the first surgery. The incidence of a POH requiring a recraniotomy significantly correlated with the incidence of a hemangioblastoma, infratentorial tumors, and a prolonged operative time (>10 h), but not with the patient age or sex, surgical procedure (biopsy or craniotomy), surgical type (primary or secondary), bleeding volume, or intraoperative blood transfusion requirement. A recraniotomy for a POH was performed in 54% of the patients just after the first operation, and within 24 h for 79% of the patients. The clinical status at the time of discharge deteriorated in 52% of the patients.

CONCLUSION

Hemangioblastomas, infratentorial tumors, and an operative time exceeding 10 h were significantly correlated with an increased risk of a POH; these factors were responsible for 12.5% of the 30-day surgical mortality rate.

Delayed supratentorial intracerebral hemorrhage following posterior fossa surgery

Delayed supratentorial intracerebral hematoma after posterior fossa surgery is uncommon. Only few cases have been reported in the past. The cause has been attributed to sitting position leading to changes in intracranial arterial and venous pressures. We report two cases of delayed intracerebral hematoma following posterior fossa surgery, none of which were operated in sitting position. MR venogram done in one patient showed venous sinus thrombosis. Intracererbal hematoma following infratentorial surgery is uncommon and is possibly due to venous sinus thrombosis leading to venous hypertension. Control of bleeding from venous sinuses due to avulsion of emissary veins during craniotomy/craniectomy possibly induces sinus thrombosis that may propagate antegrade or retrograde, leading to venous hypertension and parenchymal bleed.

Multiple supratentorial intraparenchymal hemorrhage after posterior fossa surgery

Background:

The intraparenchymal supratentorial hemorrhages after interventions of the posterior fossa is a very rare complication, with very little literature and its precise incidence is unknown (range of 0.4–1.6%). It possesses potentially an etiology diverse from that associated with other postoperative bleeding.

Case Description:

A white, 23-year-old female, with no history of coagulation disorders or other diseases, was referred to our hospital with a large ependymoma, which extended from the floor of the fourth ventricle, emerged from the foramen of Magendie and descended to the C2 level. The patient was submitted to surgical treatment and during resection of the lesion, when near the vagal trigone, the patient presented great pressure lability. In the immediate postoperative period, the patient did not have a level of consciousness sufficient to tolerate extubation. Brain computed tomography (CT) was carried out, which showed multiple supratentorial hemorrhages. On the ninth day of the postoperative period, there was a sudden neurological worsening and anisocoria. A new brain CT was carried out [Figure 4], which demonstrated a diffuse cerebral edema. In spite of the introduction of clinical measures for the control of diffuse cerebral edema, the patient evolved to brain death.

Conclusions:

The principal measures in the management of these cases include early diagnosis, detection of possible coagulation disorders, continual monitoring, and maintenance of adequate cerebral perfusion. Surgical treatment is recommended in cases of the presence of mass effect or diffuse edema not yielding to clinical treatment. High rates of mortality and morbidity are observed.

Unexpected ruptured aneurysm during posterior fossa surgery

BACKGROUND AND IMPORTANCE

Surgery is the recommended treatment for unique significant cerebellar metastasis, particularly in cases of hydrocephalus. Complications of posterior fossa surgery are associated with high risk of morbidity and mortality. We present a unique case of unexpected peroperative rupture of a cerebellar superior artery aneurysm during posterior fossa surgery.

CLINICAL PRESENTATION

During posterior cranial fossa surgery, severe arterial bleeding occurred in front of the medulla oblongata. Immediate postoperative computed tomographic (CT) angiography revealed a fusiform aneurysm from a distal branch of the left superior cerebellar artery.

CONCLUSION

To our knowledge, this is the first reported operative case of unexpected infratentorial ruptured aneurysm during posterior fossa surgery.

Extensive supratentorial hemorrhages following posterior fossa meningioma surgery

Remote supratentorial hematoma soon after posterior fossa surgery for the removal of a space-occupying lesion is a rare but dramatic and dreaded complication, carrying significant morbidity and mortality. A 47-year-old woman presented with headache of 1-year duration that worsened over last 2 months, progressive ataxia of 2 months’ duration, blurring and diminution of vision of 2 months’ duration and forgetfulness of 2 months’ duration. Fundus showed bilateral papille dema, and visual acuity was 6/9 in both eyes. She had left-sided cerebellar signs. There were no focal motor or sensory neurological deficits. MRI brain with contrast showed a large posterior fossa tumor with obstructive hydrocephalus. The patient underwent left paramedian suboccipital craniectomy in prone position with left side up. In the immediate postoperative period, the patient did no recover from anesthesia and was persistently drowsy. Immediate repeat CT scan showed diffuse subarachnoid hemorrhage spread all over the bilateral cerebral hemispheres with diffuse cerebral edema. The patient recovered with conservative management without deficits. This case stresses the importance of early postoperative CT scan and optimal management of the hemorrhage for good outcome.

Multiple supra- and infratentorial intraparenchymal hemorrhages presenting with seizure after massive sacral cerebrospinal fluid drainage

STUDY DESIGN

Case report and review of the literature.

OBJECTIVE

To describe a case of multiple supra- and infratentorial hemorrhages after spinal surgery presenting with seizure.

SUMMARY OF BACKGROUND DATA

Cerebrospinal fluid overdrainage is a well-documented factor associated with remote cerebellar hemorrhage, but supratentorial hemorrhages after spinal surgery have been reported rarely.

METHODS

A 64-year-old woman underwent a sacral laminectomy for recurrent chordoma. A negative pressure wound drain was left in after surgery and drained 1300 mL in the first 48 hours. On the fourth postoperative day, the patient presented with tonic-clonic seizures.

RESULTS

Diagnostic imaging showed multiple supra- and infratentorial intraparenchymal hemorrhages and a massive sacral cerebrospinal fluid leak. The patient underwent emergent surgery for a primary repair of the presumed dural defect.

CONCLUSION

Patients who present with severe positional headache, altered mental status, or tonic-clonic seizures after undergoing intradural spinal procedures involving massive cerebrospinal fluid loss may be suffering from multiple supra- and infratentorial intracranial hemorrhages.

Contralateral acute subdural hematoma occurring after removal of calcified chronic subdural hematoma

Supratentorial craniotomy for a nontraumatic lesion complicated by an acute subdural hematoma on the opposite side is rare. A 47-year-old woman presented with progressive headache and dizziness with no significant past history. Neuroimaging studies revealed a very large calcified chronic subdural hematoma over the entire right hemisphere with prominent mass effect. Despite a near total excision of the hematoma including the inner membranes by a large craniotomy with meticulous dissection, the brain parenchyma remained depressed. The dead space was therefore filled with saline and the operation was completed as usual. Repeat computed tomography scan for signs of left tentorial herniation demonstrated an acute contralateral subdural hematoma with severe shift of midline structures. We propose a prevention strategy for this event, which has not been previously described. We also discuss possible mechanisms involved in this unexpected complication.

Brain shift is central to the pathogenesis of intracerebral haemorrhage remote from the site of the initial neurosurgical procedure

Intracerebral haemorrhage remote from the site of surgery is an uncommon and poorly understood complication after neurosurgical procedures. Although patients under anticoagulant therapy or with perioperative elevated blood pressure are usually considered potentially at high risk of postoperative intracerebral haemorrhage, the aetiology is still unclear for patients without these predisposing factors. In this paper, we suggest that brain shift, unavoidably occurring during all neurosurgical procedures, might play a central role in the aetiology of postoperative remote intracerebral haemorrhage. Brain shift is mainly caused by gravity, aggressive intraoperative dehydration, and cerebrospinal fluid aspiration. Brain shift produces stretching and transient occlusion of the corticodural bridging veins draining into the peripheral dural sinus. Consequently, venous infarcts occur in the venous drainage territories and haemorrhagic transformation results when perfusion is re-established within ischemic tissue. To minimize brain shift and consequent risk of remote intracerebral haemorrhage, we recommend avoiding the use of hyperosmotic agents and cerebrospinal fluid drainage systems during neurosurgical procedures. Moderate head elevation during and immediately after surgery may improve cerebral venous drainage and reduces the risks of this life-threatening complication.

Superatentorial intracerebral hemorrhage following infratentorial surgery

Supratentorial hematoma following infratentorial surgery is rare. We present two such patients with remote site supratentorial hematoma after posterior fossa surgery. In one patient, a supratentorial hematoma developed following surgery for an acoustic tumor. The supratentorial hematoma was located near where a supratentorial meningioma was excised five days before. No hematoma was seen on the immediate postoperative CT scan. In another patient there were two tumors, one in the pons and the other in the basal ganglia. This patient developed a basal ganglia hematoma following brain stem surgery. In both the patients, hematological profile revealed a coagulation abnormality following the posterior fossa surgery. Our first case stabilized conservative management, whereas the second required surgical evacuation of the hematoma. The differential diagnosis of declining level of consciousness after posterior fossa surgery must include supratentorial intracerebral hemorrhage and CT scan of the head is the diagnostic test of choice.

Bifrontal epidural haematomas following surgery for occipital falcine meningioma: an unusual complication of surgery in the prone position

A 25 year old lady underwent surgery for a left occipital falcine meningioma. The patient was positioned prone and following an occipital carniotomy, total excision of the tumour was performed. In the postoperative period, she developed bifrontal epidural haematomas, for which surgical evacuation was performed. Intracerebral haematomas distant from the site of craniotomies are uncommon and epidural haematomas are extremely rare. The literature is reviewed and the possible mechanisms causing this complication are discussed.

Remote cerebellar hemorrhage after supratentorial surgery

OBJECTIVE

Remote cerebellar hemorrhage (RCH) is an infrequent and poorly understood complication of supratentorial neurosurgical procedures. We retrospectively compared 42 patients who experienced RCH with a case-matched control cohort, to delineate risk factors associated with the occurrence of this complication.

METHODS

Between 1988 and 2000, 42 patients experienced RCH after supratentorial neurosurgical procedures at our institution. Diagnoses were made on the basis of postoperative computed tomographic or magnetic resonance imaging findings in all cases. The medical records for these patients were reviewed and compared with those for a control cohort of 43 patients, matched for age, sex, surgical lesion, and type of craniotomy, who were treated during the same period.

RESULTS

RCH most commonly occurred after frontotemporal craniotomies for unruptured aneurysm repair or temporal lobectomy and was frequently an incidental finding on postoperative computed tomographic scans. However, some cases of RCH were associated with significant morbidity, and two patients died. Preoperative aspirin use and elevated intraoperative systolic blood pressure were significantly associated with RCH (P = 0.026 and P = 0.036, respectively). Pathological findings for two cases demonstrated hemorrhagic infarctions in both.

CONCLUSION

RCH most commonly follows supratentorial neurosurgical procedures, performed with the patient in the supine position, that involve opening of cerebrospinal fluid cisterns or the ventricular system (such as unruptured aneurysm repair or temporal lobectomy). Preoperative aspirin use and moderately elevated intraoperative systolic blood pressure are potentially modifiable risk factors associated with the development of RCH. Although RCH can cause death or major morbidity, most cases are asymptomatic or exhibit a benign course. Cerebellar "sag" as a result of cerebrospinal fluid hypovolemia, causing transient occlusion of superior bridging veins within the posterior fossa and consequent hemorrhagic venous infarction, is the most likely pathophysiological cause of RCH.

Intracerebral hemorrhage complicating cervical "hourglass" schwannoma removal. Case report

The authors report a case of infra- and supratentorial intracerebral hemorrhage complicating the postoperative course of a patient who had undergone surgical removal of a cervical schwannoma with an hourglass configuration. To their knowledge, this is the first case in which this neurosurgical procedure was followed by such a complication. Possible mechanisms are discussed; however, pathological events leading to this complication are unclear. The development of new neurological deficits not attributable to the surgical procedure should suggest this possibility.

Chronobiological patterns of onset of acute cerebrovascular diseases

There is a considerable amount of data indicating that several major unfavorable cerebrovascular events are not randomly distributed over time, but show a peculiar distribution along the day, the week, and the months of the year. The authors review the available evidence on the chronobiological (circadian, weekly, and seasonal) patterns of onset of acute cerebrovascular diseases and variations in their possible triggering mechanisms. The existence of a peculiar chronobiological pattern in the onset of acute cerebrovascular disease, characterized by both circadian (morning and evening occurrence), circaseptan (last and first days of the week), and circannual (especially in winter) is confirmed, although differences depending on biological (gender, age), pathological (diabetes, hypertension, smoke, alcohol), cultural, social, and environmental factors exist. A deeper knowledge of the underlying pathophysiologic mechanisms could provide more effective insights for both preventive strategies and optimization of therapeutic approach.

Intracerebral hemorrhage occurring remote from the craniotomy site

OBJECTIVE

The purpose of this study was to analyze the available clinical data on postoperative intracerebral hemorrhages that occur in locations remote from the sites of craniotomy.

METHODS

The findings of 37 cases of postoperative intracerebral hemorrhages occurring remote from the craniotomy sites were reviewed (5 from our records and 32 from the literature).

RESULTS

Remote postoperative intracerebral hemorrhages presented within the first few hours postoperatively in 78% of the patients and were not related to the types of lesions for which the craniotomies were performed. Supratentorial procedures that produced infratentorial hemorrhages involved operations in the deep sylvian fissure and paraclinoid region in 81% of the patients and hemorrhages in the cerebellar vermis in 67% of the patients. Infratentorial procedures that produced supratentorial hemorrhages were performed with the patient in the sitting position for 87% of the patients. The remote supratentorial hemorrhages that occurred were superficial and lobar in 84% of the patients, as opposed to deep and basal ganglionic, which are classic locations for hypertensive hemorrhages. Remote intracerebral hemorrhages occurring after craniotomies were not associated with hypertension, coagulopathy, cerebrospinal fluid drainage, or underlying occult lesions. These hemorrhages commonly led to significant complications; 5 of 37 patients (14%) were left severely disabled, and 12 of 37 patients (32%) died.

CONCLUSIONS

Remote intracerebral hemorrhage is a rare complication of craniotomy with significant morbidity and mortality. Such hemorrhages likely develop at or soon after surgery, tend to occur preferentially in certain locations, and can be related to the craniotomy site, operative positioning, and nonspecific mechanical factors. They do not seem to be related to hypertension, coagulopathy, cerebrospinal fluid drainage, or underlying pathological abnormalities.

Cerebellar hemorrhage complicating temporal lobectomy. Report of four cases

Four cases of cerebellar hemorrhage complicating temporal lobectomy are presented. A case of postoperative hemorrhage located remote from the operative site as a complication of intracranial surgery is rare, especially when it involves the cerebellum after supratentorial craniotomy. In a review of the literature, the authors identified only 12 such cases, none of which was described in the setting of a temporal lobectomy. The possible etiologies for cerebellar hemorrhage in the four cases presented are examined, including the role of epidural suction drains and the position of the head during surgery. The mechanism of cerebellar hemorrhage in this series of patients is probably multifactorial. Special attention throughout the perioperative course must be given to hemodynamic, anatomical, and physiological factors that together can affect the patient negatively.

Contralateral cerebellar hemorrhagic infarction after pterional craniotomy: report of five cases and review of the literature

OBJECTIVE AND IMPORTANCE

Five cases of cerebellar hemorrhagic infarction complicating pterional craniotomy are presented. Recognition of this rare complication may be delayed, with catastrophic consequences, because clinicians are unaware of the possibility. We suggest that the mechanism of this complication is dislocation of the dependent part of the cerebellum and venous obstruction causing hemorrhagic infarction.

CLINICAL PRESENTATION

Five patients undergoing pterional craniotomies for benign conditions (four unruptured aneurysms and one meningioma) developed hemorrhagic infarction of the contralateral cerebellum in the postoperative period. This resulted in obstructive hydrocephalus and brain stem compression. A review of the literature revealed only one previous report of a similar complication in patients with gross coagulopathy. This was not a problem in our patients.

INTERVENTION

The time of onset of symptoms varied from immediately postoperative to 24 hours later. Once the diagnosis was made, the hydrocephalus was drained and the posterior fossa was decompressed.

CONCLUSION

The outcome depended on two variables: 1) the rate of development of hemorrhagic infarction and the associated complications and 2) the amount of time that elapsed before remedial action was taken. Two patients with the first signs of deterioration in the immediate postoperative period had the worst outcome; one died and the other remained severely disabled. In two patients with good neurological recovery, problems were identified and corrected within 4 hours of the first sign of deterioration. Rapid overdrainage of cerebrospinal fluid during supratentorial surgery should be avoided, and the fluid volume should be replaced before closure. Postoperative evaluation of patients whose conditions deteriorate after supratentorial craniotomy should include adequate imaging studies of the posterior fossa.

Remote subarachnoid haemorrhage in the posterior fossa following supratentorial surgery. Clinical observation of 6 cases

Haemorrhage in regions remote from the site of following intracranial operations is rare, but they do occur. We performed supratentorial craniotomy on 639 patients between the time of introduction of computed tomography (CT) for clinical use in 1983 and June 1992; subarachnoid haemorrhage (SAH) in the posterior fossa occurred postoperatively in six of these cases. These included four patients with tumours in the sellar region, one with an arteriovenous malformation (AVM) and one who underwent superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis. The ages of the six patients ranged from 17-72 years. Haemorrhage occurred on the day of operation in one case and was detected on CT examination on the day following surgery in the remaining five cases. Of three patients with disturbance of consciousness, two underwent suboccipital craniectomy for reduction of intracranial pressure, while one received barbiturate therapy and later underwent cerebrospinal fluid (CSF) shunt surgery. No special treatment was necessary for the remaining three patients with less serious lesions. Five of the six patients ultimately recovered their pre-operative neurological status apart from the primary diseases. Factors inducing such haemorrhages seem likely to include displacement of the cerebellum by reduced CSF pressure during and after operations, and stretching and tearing of the veins and venules in the sulci of the tentorial surface of the cerebellum. Consideration should therefore be given to the maintenance of an appropriate CSF pressure during operation; this is particularly important in elderly patients and those with an atrophied cerebral cortex.

Cerebellar hemorrhage complicating supratentorial craniotomy: report of two cases

One of the rare complications of supratentorial craniotomy is the occurrence of a hematoma in the cerebellum. Only seven previous cases have been published, and these have been ascribed to disturbed blood coagulation or decreased intracranial pressure. We present two similar patients, in whom, however, the pathogenetic role of these factors seems improbable.

Circadian rhythmicity of stroke onset. Intracerebral and subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Our purpose was to describe and further understand the determinants of the time of onset of parenchymatous intracerebral hemorrhage and subarachnoid hemorrhage in patients enrolled in the Stroke Data Bank.

METHODS

We analyzed the observed times of onset of intracerebral hemorrhage (n = 237 patients) and subarachnoid hemorrhage (n = 243 patients) compared with expected times of onset if the probability of onset was constant across all time intervals. We also analyzed the role of clinical features (if any) in explaining the findings.

RESULTS

For intracerebral hemorrhage, 52.5% of patients reported onset times between 0600 hours and 1400 hours, with peak onset between 1000 and 1200 hours (chi 2 = 62.94, df = 11, p less than 0.001). Patients with subarachnoid hemorrhage were more likely to lack a history of hypertension compared with patients who had intracerebral hemorrhage (chi 2 = 23.3, df = 1, p less than 0.001). Patients with subarachnoid hemorrhage were more likely to have more uniform onset time throughout the day (chi 2 = 12.92, df = 7, p = 0.074). However, subarachnoid hemorrhage patients with a history of hypertension were more likely to have peak onset times in mid-to-late morning compared with patients without such a history (chi 2 = 35.25, df = 10, p less than 0.001). The nonuniformity of onset times for intracerebral hemorrhage persisted even if patients with unknown onset times were treated as through their onset times were randomly distributed between 0000 and 0800 hours. Seasonal periodicity and the relation between initial systolic or diastolic blood pressure and time of onset for either type of hemorrhage were not observed.

CONCLUSIONS

Our data suggest that the time of onset for both intracerebral hemorrhage and subarachnoid hemorrhage patients with a history of hypertension is similar to the diurnal variation in blood pressure.

Hemifacial spasm: a review

Hemifacial spasm can be diagnosed by observation and clinical history. It is thought to arise primarily from compression of the facial nerve at the pons, usually by an adjacent artery. Although many approaches to treatment have been tried, the most effective is microvascular decompression of the facial nerve at the pons. That operation has well-recognized risks, including ipsilateral deafness. The latter complication ordinarily can be avoided by the use of intraoperative monitoring of auditory evoked potentials.

Cerebellar haemorrhage as a complication after supratentorial craniotomy

Four cases are presented, in whom cerebellar haemorrhages appeared as a complication following supratentorial craniotomy for a giant aneurysm, for tumours in three cases. Two patients died. Intracranial hypotension in combination with disturbed blood coagulation is discussed as possible pathogenesis. Because this seems to be a rare complication--similar cases have not yet been described in the literature--its timely diagnosis may be missed.

Postoperative intracerebral haemorrhages remote from the site of the initial operation

Two cases of postoperative intracerebral haemorrhages remote from the site of the initial craniotomy for saccular aneurysms are reported and the other cases from the literature are reviewed. Lack of a good postoperative recovery and the appearance of neurological signs not related to the site of the operation may suggest this complication, which is associated with high mortality and disability rate. The possible pathogeness of those postoperative haemorrhages is discussed.

Pneumocephalus and tension pneumocephalus after posterior fossa surgery in the sitting position: a prospective study

Thirty patients subjected to posterior fossa surgery in the sitting position were evaluated postoperatively by CT scans in order to assess the true incidence of pneumocephalus and subsequent development, if any, of tension pneumocephalus. This prospective survey shows that the postoperative incidence of intracranial air was 100%, while no progression towards tension pneumocephalus producing severe neurological deterioration was observed. It can thus be claimed that, although the sitting position may favour the development of tension pneumocephalus also other factors contribute to its pathogenesis. Finally, neither nitrous oxide nor temperature play any significant role in the development of this complication.

Postoperative intracerebral hemorrhages: a survey of computed tomographic findings after 1074 intracranial operations

We surveyed computed tomographic findings after 1074 intracranial operations to determine the incidence and etiology of postoperative intracerebral hemorrhages. Medium or large hemorrhages occurred after 42 operations (3.9%). Larger hemorrhages, hemorrhages in the suprasellar region, and hemorrhages associated with other types often preceded a poor outcome. Major etiologies underlying postoperative intracerebral hemorrhages were uncontrolled bleeding from a blind area, difficult dissection of a tumor from the brain, retraction injury, vessel injury from a needle, bleeding from a residual tumor, local hemodynamic changes after removal of a tumor, premature rupture of an aneurysm, and hypertensive putaminal hemorrhage. Hypertension during recovery from anesthesia was another important factor.

Supratentorial space occupying lesions following infratentorial surgery early diagnosis and treatment

Supratentorial complications of infratentorial surgery are rare. In the last 3 years we have operated on 187 patients with infratentorial lesions and have observed an incidence of 3.7% of supratentorial haemorrhages. Postoperative intracranial air, as shown by early postoperative CT control, was encountered mainly in a subdural frontal location and within the interhemispheric fissure. We performed no surgical decompression of the air accumulation because of the lack of clinical symptoms. Predisposing factors for the development of supratentorial complications remote from the surgical area are hypertonia, female sex, brain atrophy and preoperative shunting procedures. Measures to avoid these complications are discussed.

Subdural tension pneumocephalus. Report of two cases

Two patients developed subdural tension pneumocephalus after undergoing posterior fossa surgery performed in the sitting position. The mechanism for entry of air into the intracranial compartment is analogous to the entry of air into an inverted soda-pop bottle. As the fluid pours out, air bubbles to the top of the container. We have thus referred to this as the "inverted pop-bottle syndrome." Computerized tomography provided prompt diagnosis and confirmed brain displacement. Twist-drill aspiration of the air resulted in improvement in both patients, although one patient subsequently died from an intracerebellar hemorrhage. Tension pneumocephalus appears to be another potential complication of posterior fossa surgery in the sitting position. This condition is easily diagnosed and treated, and should be considered whenever a patient fails to recover as expected following posterior fossa surgery.