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Objective: The aim of this study was to assess the value of monitoring somatosensory evoked potentials (SEP) in the prevention of ischaemic stroke occurring during surgical exclusion of middle cerebral artery aneurysms., Methods: SEP monitoring was performed during the surgical exclusion of 131 aneurysms in 122 patients. All SEP variations over 30% were notified to the surgeon and those over 50% were considered as highly significant. If this happened, and in concert with the conduct of the operation, a return to the basal level was systematically sought., Results: Post-operative ischemic stroke was observed after 15 (11.4%) operations, leading to a permanent neurological deficit in 12 (9.2%). During nine (6.9%) operations there was a highly significant SEP change that persisted, or was only partially reversed, after corrective procedure. Nine of these patients had a post-operative ischaemic stroke. In 25 (19%), operations there was a highly significant SEP change followed by complete recovery. Of these 25 patients, 2 suffered a post-operative ischemic stroke. Following 49 operations (37.4%) with less significant SEP modifications, 4 patients suffered a post-operative stroke (8%). A stroke did not occur in the 48 (36.6%) operations during which there was not a variation in SEP. The strokes were related to temporary clipping in 9 patients to definitive clipping in 3 to sylvian fissure opening in 1 to brain retraction in and to dissection of the aneurysm in 1 (1 case)., Conclusion: Changes in the SEP correlated well with the occurrence of post-operative stroke. This early detection of ischemia directs attention to the need for measures such as withdrawal of temporary clipping or identification of another factor (e.g. release of brain retraction or repositioning of an occlusive clip) so that the risk of post-operative is reduced.

In the acute phase, spontaneous intracerebral hemorrhage is surrounded by hypodensity, the origin of which is controversial. Its clinical consequences are still under evaluation. Surrounding cerebral ischemia was suggested as its main etiology, but no experimental or clinical data currently supports this etiology. The hypodensity reflects the presence of cytotoxic and vasogenic edema secondary to prolonged contact between hemorrhage and adjacent brain tissue. This would mainly be due to local release of activated thrombin. However, other metabolites released from blood degradation products would also be involved. This edematous process is unique due to its early occurrence (as early as 2 hours), early maximum peak (24 hours), and regression over the next few days. In humans, no definitive proof exists that this edematous process of variable intensity is pathological. No specific treatment is currently available.

In the initial phase of severe head injury, dysautonomic abnormalities are frequent. Within the framework of a prospective study, evaluating the efficacy of continuous intrathecal Baclofen therapy (CIBT) on hypertonia during the initial recovery phase of severe head injury, the authors report on the preliminary results of this treatment on paroxysmal dysautonomia about four patients. Continuous intrathecal Baclofen infusion was first delivered, for a test period, continuously for 6 days. If a relapse of dysautonomia occurred at the end of the test period, an implantation of a continuous intrathecal infusion pump delivering Baclofen was performed. Results were assessed with four continuous variables; duration (days), dose of Baclofen per day (microg/d), number of dysautonomic paroxysmal episodes per day, and initial recovery evaluated by a scale of the first initial stages of head injury coma recovery. For three patients: (1) the number of dysautonomic paroxysmal episodes per day and the doses of Baclofen during the follow-up period were correlated (p = 0.02, p < 0.001, p = 0.008, respectively, distribution-free test of Spearman), (2) during the test period and the relapse after the test period, the number of paroxysmal episodes and the Baclofen dose are correlated to p < 0.05, p = 0.03, p = 0.04, respectively (distribution-free test of Spearman). The second statistical test was used to prove that Baclofen doses and number of paroxysmal dysautonomic episodes are correlated independently of the duration of follow-up. The fourth patient improved with CIBT without any recurrence at the end of the treatment test period. For the four patients, recovery score increased during the overall follow-up. In the authors' experience CIBT is very efficient to control paroxysmal dysautonomia during the initial recovery phase in severe head injury, and seems to facilitate recovery.

Background and Purpose: Microsurgical exclusion of a cerebral arteriovenous malformation (AVM) can compare favorably with radiosurgery. We sought to assess its rate of morbidity-mortality as it is presently reported in the literature, and to discuss some of its current and worthwhile indications., Methods: Through Medline and additional searches by hand, we retrieved studies reporting the clinical and angiographic results after microsurgical excision of an AVM published between january 1990 and december 2000., Results: a) Postoperative mortality was 3.3% (68/2 452 patients from 25 studies). Permanent postoperative morbidity was 8.6%. Morbidity was never absent varying from 1.5% to 18,7%. The morbidity-mortality rate increased with an increasing Spetzler-Martin's grade, and was related to the location of the AVM. A 4.6% morbidity (from 1.5% to 9.7%) and a zero mortality were reported after microsurgical removal of small lesions of less than 3 cm in diameter. b) Postoperative angiography confirmed a total excision of the AVM in 97% of the cases (1 050/1 076 patients over 11 series), varying from 91% to 100%. c) Permanent morbidity related to pre-surgical embolization varied from 4% to 8.9%. Results from multiple or combined treatment including microsurgery could not be summed up., Conclusions: A complete and definitive microsurgical excision of an AVM can be achieved with a high success rate and a low morbidity-mortality rate, according to sound indications and to the neurosurgeon's personal experience. The choice for a best treatment of an AVM is no longer limited to microsurgery; it is a team decision where the neurosurgeon plays a determining role.

Background and Purpose: Are chronic bilateral subdural hematomas different from unilateral forms in terms of delay of diagnosis, clinical presentation and post-operative recovery or recurrence?, Methods: Etiological, clinical, and radiological aspects and management outcome of bilateral chronic subdural hematomas consecutively managed from 1990 to 1995 were retrospectively analyzed and compared with unilateral forms managed in the same neurosurgical unit during the same period of time., Results: There were 236 cases. Bilateral subdural hematomas occurred in 41 patients (17.4%). A good outcome was obtained in 97.5% of the cases and morbidity was 14.6%. The differences significantly observed between unilateral and bilateral subdural hematomas were duration of the prediagnostic period, pneumatoceles and recurrence rates (12%). Recurrences were all observed during the first postoperative month and treated with the same initial standardized procedure. The rate of infection or epileptic seizures was low., Conclusions: There are few limited differences between uni- and bilateral chronic subdural hematomas. In the latter, a possible correlation between the duration of prediagnostic period and an increased rate of recurrence could be explained by poorer cerebral reexpansion. The overall prognosis of bilateral hematomas is comparable with that observed in unilateral forms. A simple and routinely used burr hole procedure either under local or general anesthesia associated with closed drainage is a safe surgical procedure for either bilateral or unilateral forms and can be performed in all the cases including recurrences. Systematic antiepileptic drugs or antibiotherapy are unnecessary in the medical management of chronic subdural hematomas. One late delayed postoperative clinical control seems to be sufficient.

Modalities of management of arterio-venous malformations are discussed according to natural history and size of lesion, patient clinical status, and potential side effects of available techniques (microsurgery, radiosurgery, ambolization). Clinical cases illustrate this discussion.

Background: The posterior fossa localization of amyloid angiopathy-related hemorrhage is very unusual. Less than 10 cases have been previously reported. Surgical management of amyloid angiopathy-related hemorrhage is the subject of controversy., Results: Typical aspects of amyloid angiopathy were found within the surgically removed biopsies of 71-year-old nonhypertensive, nondemented woman suffering cerebellar hemorrhage., Conclusions: Amyloid angiopathy-related hemorrhage could occur in the cerebellum, and diagnosis might be suspected when no past history of mental deterioration and/or arterial hypertension are present and when angiography rules out vascular malformation. Surgical management seems to have the same restricted indications as in other brain areas.

Baclofen is used for the treatment of post-traumatic spasticity. It carries a risk of overdose as well as of an acute withdrawal syndrome. We report two cases of severe hypertonia and hyperthermia (> 42 degrees C), occurring after accidental discontinuation of intrathecal infusion of baclofen. Both hypertonia and hyperthermia ceased when administration of baclofen was resumed. In parallel, the patients developed transient life-threatening alterations of hepatic (cytolysis), haematologic (coagulopathy) and cardiorespiratory functions for some days. It is concluded that the occurrence of such a withdrawal syndrome should be prevented, especially in patients with chronic intrathecal administration and first symptoms should be recognized without delay. Relationships with other malignant hyperthermias are discussed.

The clinical and imaging features of a paraganglioma of the cauda equina are presented. A peridural anesthesia revealed the cauda equina compression syndrome in a 68 years old man who presented first with a urinary retention. Total surgical excision of a long round-shaped encapsulated tumor was uneventful. Macroscopically this lesion filled up the spinal canal and resembled to a meningioma. It was firmly attached to the filum terminale. Adjacent large arterialized vessels visible on MRI were spared. Although the diagnosis could be evoked pre-operatively on some suggestive patterns on the MRI, the pathological findings finally confirmed the diagnosis of paraganglioma. Along with the evidence of specific light microscopic features, the use of an immunocytochemical demonstration of synaptophysine in these tumors allows a confident diagnosis to be made.

This text summarizes the course organized for residents and trainees by the Société de Neurochirurgie de Langue Française. It was presented by the authors during the annual winter meeting held in Paris in December 1992. The aim of this course was to discuss all the technical points needed to achieve safely a microsurgical clipping of an intracranial aneurysm of the anterior circulation. Although many of these technical points discussed can apply to any kind of intracranial aneurysm, the very specific difficulties of the treatment of giant aneurysms or posterior circulation aneurysms were not mentioned. The usual pterional approach is described. The need of having a slack brain to perform easily the dissection of the aneurysm is stressed. Standards of hemodynamic control during surgery are described either with the use of a total or a proximal temporary clipping under the electrophysiologic control of the somesthetic evoked potential. Prevention of peroperative cerebral ischemia and brain protection are discussed. Dissection of the aneurysm is presented step by step until clipping. Different ways of clipping are discussed after a short description of the characteristics and composition of various available clips. How to deal with a premature intra-operative rupture of the aneurysm is also discussed. The last chapter describes step by step the approach and clipping of the four most frequent aneurysm locations i.e. at the posterior face of the intracranial internal carotid artery, the intracranial carotid bifurcation, the middle cerebral artery, and the anterior communicating artery.

As proposed by Marmarou in 1976, in case of acute hydrocephalus high intracranial pressure (I.C.P.) can be controlled by withdrawing the ventricular cerebrospinal fluid (C.S.F.) at a constant rate equal to the rate of C.S.F. formation. We experienced this procedure since 1989 in 17 patients presenting with acute hydrocephalus consecutive to aneurysmal subarachnoid hemorrhage (11 cases) or infratentorial mass (6 cases). A ventricular catheter was connected to an electrical syringe of which the motor driving direction has been inverted. Using an outflow rate ranging from 0.15 to 0.20 ml/mn, i.e. lower than the physiological C.S.F. rate formation, this controlled continuous mechanical ventricular C.S.F. drainage has serious advantages compared to a traditional external ventricular C.S.F. drainage. These advantages are mainly the better control of intracranial pressure (fiability of I.C.P. monitoring, lowered risk of hyperdrainage), more comfort for the patient and the nursing staff and lower cost.

Using death and functional status as end points, we prospectively analyzed the outcome 6 months after spontaneous intracerebral hemorrhage in 166 patients admitted to an acute-care stroke unit on the first day of their stroke. Seventy-one patients (43%) died, 69 (42%) had a satisfactory outcome, and 26 (16%) had a poor functional outcome. Early (30-day) survival was correlated with morphologic parameters on the initial computed tomogram (hemorrhage size, midline shift, and intraventricular spread of the hemorrhage), while later (6-month) survival was correlated with age. Using logistic regression, we found five independent predictors of satisfactory outcome at 6 months: age, hemorrhage size, intraventricular spread of the hemorrhage, limb paresis, and communication disorders. Of these, age was the most important predictor by far.

This paper reports the findings of a study of head trauma conducted over a one-year period within a defined region with a population of 2.7 million (Aquitaine, France). It includes cases resulting in death prior to hospitalization or requiring hospitalization. During the one-year period, 391 deaths and 8549 hospital admissions due to head trauma occurred, yielding an annual estimate of 8940 head-injured people. The immediate case-fatality rate was 4.4%. Among non-fatal cases, 80% were mild, 11% moderate and 9% severe. The overall annual incidence was 281/100,000 in both sexes (384 and 185/100,000 in males and females respectively). The annual death rate was 22/100,000 (33 and 12, respectively). Patterns of incidence by age and sex were in general agreement with earlier studies. The main causes of head trauma were traffic accidents (60%) and falls (33%). One-third of hospitalized patients had no injury other than the head trauma. The most frequently associated injuries were those involving extremities, whereas the most severe were those involving the abdomen. The Injury Severity Score (ISS) ranged from 4 to 66, with a mean of 9 and a median of 5. At the eighth day following injury, 25% of hospital-treated patients were still hospitalized and 2% had died. The outcome correlated well with the ISS.

Decision theory can be useful for the determination of an optimal diagnostic and/or therapeutic strategy. Of course, the physician remains the only decision-maker, but these methods, quite simple, introduce a scientific background to medical decisions by the quantitative evaluation of the consequences of the choices. We will present the use of such a methodology in the treatment of adults presenting hydrocephalus.

Radionuclide quantitation of cerebrospinal fluid (CSF) flow through a ventricular shunt using a Cordis-Hakim valve was performed in 78 adults (138 studies). All remained supine for at least two hours before the study to avoid possible depletion of ventricular CSF. The absolute flow rate distinguished shunt adequacy from patency by defining flow of less than 0.1 ml/min. as abnormal. Measurements were performed with the patient first supine and then erect. When abnormal supine flow was the criterion of malfunction, all obstructions were detected but there were 6 false positives. When abnormal erect flow was considered, there were 5 false negatives. Abnormal flow in both supine and erect positions is a reliable indication of malfunction. The authors conclude that this technique is valuable for neurosurgical management of ventricular shunts.

When ICP measurement is used for a neuro-surgical patient we wonder about two questions: --which are the highest and the mean ICP value? --is there some spontaneous pathological variations like plateau wave or b wave? To answer these questions it is necessary to record ICP for extended periods of time. Numerical values are difficult and tedious to set up from ICP standard recordings. To resolve this practical problem, JANNY and KULLBERG had proposed a statistical automatic analysis of the different ICP values using a computer. The modal curve of the different classes of ICP amplitudes is then recorded. For 62 patients with various pathological situations (head injury subarachnoid hemorrhage, posterior fossa tumor, normal pressure hydrocephalus and dementia with symetric ventricular enlargement...) ICP has been recorded during 12 hours at the same time on the standard ink-writer recorder, and on a standard multichannels automatical analysis giving the modal curve of ICP amplitudes. On the round-headed modal curve obtained, ICP modal value i.e. the most frequent pressure value, can be read directly. ICP variations beyond this modal value like plateau wave or vasomotor variations modify the general aspect of this modal curve and sometimes in a specifical manner as regarded to the pathological situation. In our findings posterior fossa tumor without high modal ICP level are frequent but in these cases vasomotor response are nevertheless always present. In cases of normal pressure hydrocephalus as defined by clinical aspect, ventriculography and cisternography, the ICP modal value is higher than 12 mm Hg and vasomotor variations like B wave occurs frequently. The most typical monophasic aspect has been noticed in cases of metastatic meningitis. This technical approach of ICP measurement is very useful and gives immediately to the clinician the exact mean or modal ICP value as measured on the modal curve of the different ICP amplitudes with more accuracy and attainability than on the usual long term recordings.

Sixty-five patients with a mean age of 50.2 +/- 10.9 were admitted with a subarachnoid hemorrhage and a subsequent normal cerebral panangiography. On admission, 69% of the patients were graded I or II on the Hunt and Hess scale, versus 14% of them admitted on grade IV or V. Fifty-one patients (78%) were submitted to a second angiography between day 10 and day 132 after their hemorrhage (average day 29). A third angiography was performed on twenty-six patients (40%). Angiographic vasospasm was present on 52% of the first angiograms and affected predominantly the vertebro-basilar arterial system. On the second angiography, the vasospasm was still present on 26 out of 32 angiograms performed before day 30, and was only noted on 2 out of 19 angiograms performed later. No rebleeding was recorded in this group of patients who were followed-up for an average of 49 +/- 23 months. Complication as acute hydrocephalus affected 17% of the patients. In two patients (3%), symptomatic vasospasm was judged responsible of a delayed neurological deficit with concomitant hypodensity on the CT scan. Angiographic explorations were complicated by a transient ischemic deficit in 3 cases and by a fatal stroke in one case (4 cases out of 65 procedures, or 6%). As another patient died with bronchopneumonia during the hospitalization, the initial mortality rate was 3%. During the period of follow-up, two patients died from medical causes unrelated to their initial hemorrhage. Finally, 92% of the patients were alive and in an excellent or good clinical condition.(ABSTRACT TRUNCATED AT 250 WORDS)

The work presented was initiated in order to evaluate the biological and clinical tolerance of the isotonic saline solution (9 p. mille) usually used in neuro-surgery directly in contact with the nervous tissue in comparison with a new solution proposed as a a mock cerebrospinal fluid. Clinically, two patient' populations including 75 patients each, were compared during dynamic investigation of intracranial pressure with intra-ventricular injections of different solutions. The effects of prolonged intra-ventricular perfusion with each solution were studied in animal models by: --electrophysiological analysis of EEG activity during perfusion --morphological observation: electronic microscopy of different cerebral structures after the perfusion. The biological tolerance was analyzed by the use of routine tissue culture of CNS tissue exposed to the two solutions. The results obtained show the toxicity of isotonic saline solution (9 p. mille) and the perfect tolerance of S.21.001 solution as a mock cerebro-spinal fluid.

A variety of lesions of varying complexity were noted during pathological examinations of the brain in 30 cases of acute severe traumatic coma, of whom 27 survived for less than 10 days. "Diffuse brain damage" were present in all cases and contusions were frequently noted (83 p. 100). The lesions appear immediately after, and are directly related to the injury. Ischemic lesions were present in 66 p. 100 of cases and their mechanisms of production are various and interwoven. The frequency of respiratory difficulties associated with brain injuries is stressed. Two thirds of the cases with brain stem lesions (80 p. 100) were secondary to phenomena related to trans-tentorial herniation. Clinical examinations of these patients with acute severe coma demonstrates the difficulties encountered in assessing prognosis based on clinical findings within the first 48 hours.

Six patients developed ventricular arrhythmias with parenteral administration of vincamine. Direct intravenous injection was the mode of administration in 2 cases, intravenous infusion in 3 cases (one at very high dosage) and intramuscular injection in 1 case. The same signs of toxicity were observed in al patients:--5 patients had recorded attacks of "torsades de pointe", which recurred in 1 of them when the drug was restarted.--1 patient had syncope and, although an ECG was not recorded at the time, an ECG shortly afterwards showed a long QT interval and R/T ventricular extrasystoles. Symptoms were generally neurological in nature with syncope, cyanosis, and convulsions. Spontaneous regression was observed in 3 cases but in the others the drug had to be stopped and cardiopulmonary resuscitation instituted. None of our patients died of their arrhythmia. In some patients a predisposing factor was found:--metabolic: hypokalaemia (1 case), moderate reduction of potassium pool (1 case), severe reduction of calcium pool (1 case);--pharmacological: previous treatment with fenoxidil (1 case), thioridazine (1 case);--cardiac: congenital long QT interval (Romano-Ward) (1 case), revealed by vincamine administration. Chronic obstructive airways disease with right ventricular strain and atrial fibrillation (1 case) which might have predisposed the patient to "torsades de pointes". Three patients had no predisposing factors apart from their age. "Torsades de pointes" occurred in a pacemaker patient, but pacemaker function was normal. These six cases may be grouped with the other ten or so cases of vincamine toxicity already reported; they carry and additional warning on the use of intramuscular vincamine. Vincamine toxicity is probably a direct effect on the myocardial cells. This fact merits verification by further electrophysiological studies.

A case of an hemorrhagic cavernous hemangioma of the optic chiasma and the adjacent optic nerve in a 23-year-old woman is reported. The visual disturbance has subacute onset following a sudden lateralized headache. Through a fronto-pterional approach, an intrachiasmal hematoma was evacuated. A small cavernous hemangioma was found in the hematoma cavity, and it was totally removed. Visual symptoms improved slightly postoperatively. Cavernous hemangioma involving the optic nerve and chiasma is extremely rare. Only five similar cases have been reported previously.