Incidence and effects of increased cerebral blood flow velocity after severe head injury: a transcranial Doppler ultrasound study I. Prediction of post-traumatic vasospasm and hyperemia.

Cerebral blood flow velocity was monitored in 50 patients with severe head injury (GCS 8 or less) within 24 h of injury and at least once daily thereafter, using transcranial Doppler ultrasonography (TCD). Delayed post-traumatic vasospasm occurred in 20, and cerebral hyperemia in another 15. Doppler velocities were higher in vasospasm, which also lasted significantly longer than hyperemia. The presence of visible blood on an early CT scan was of some value in predicting vasospasm only (accuracy 59%). Xenon-133 cerebral blood flow (CBF) was also measured within 24 h of injury. An abnormal early cerebral blood flow level, either above or below a narrow central range, was more effective than CT in predicting vasospasm or hyperemia (accuracy 80%), while the combination of an abnormal blood flow and hemorrhagic findings on CT scan helped to determine which of these would occur later. Patients with an abnormal early cerebral blood flow and hemorrhagic findings on CT were more likely to develop vasospasm--accuracy for prediction of vasospasm 73%. This distinction may be of great importance, since these different groups of patients may well need different management.

Incidence and effects of increased cerebral blood flow velocity after severe head injury: a transcranial Doppler ultrasound study II. Effect of vasospasm and hyperemia on outcome.

Cerebral blood flow velocities were measured in 50 severely head injured (Glasgow Coma Scale (GCS) 8 or less) patients using transcranial Doppler ultrasonography (TCD). Abnormally high TCD velocities were recorded in 35 patients; in 20 this was deemed to be due to vasospasm and in the other 15 to hyperemia. Patients who developed hyperemia also had the highest intracranial pressure (ICP) and the lowest cerebral perfusion pressure (CPP) of the three groups. Outcome was assessed at six months after injury using the Glasgow outcome scale and the disability rating scale. In the normal velocity group 87% of patients had a good outcome, compared with 47% of those with hyperemia and 40% of those with vasospasm. The highest velocity (HVEL), GCS, age, ICP and CPP were entered into a logistic regression analysis. HVEL, age and CPP were found to be the most significant predictors of outcome (chi 2 = 29.5; p < 0.0001). These factors predicted outcome with 82% accuracy, 86% sensitivity and 76% specificity. Routine monitoring of TCD velocity may be useful in detecting hyperemia and vasospasm after severe head injury, allowing appropriate treatment to be started as early as possible.

Aid to exposure of the upper basilar artery: technical note.

The author explains his method of retracting the tentorial edge during the subtemporal approach to the distal basilar artery. A modification of the ligature makes it unnecessary to tie a knot at depth.

Early experience with spiral CT in the diagnosis of intracranial aneurysms.

We report experience with 16 patients undergoing spiral CT Scans for the evaluation of cerebral aneurysms. There were 10 females and six males, aged between 36 and 73 years. The three-dimensional scanning was useful in five situations: (i) Suspicion of aneurysm on conventional scan. An aneurysm was found in one of four patients and later confirmed by angiography, and two showed arterial ectasia with no saccular aneurysm; the fourth again appeared to have an aneurysm, but this was not shown on angiography. (ii) Follow-up of previously detected aneurysms not planned for surgery. This has been done in three patients, the spiral CT findings correlating well with previous angiography. (iii) Follow-up of aneurysm remnants after surgery (three cases); findings correlate well with previous angiography, and clips cause no artefact problems. (iv) Detection of ruptured aneurysms. In two cases, small aneurysms were found that had been missed on angiography, and in a third, with doubtful angiographic findings, spiral CT was useful. (v) Investigation of patients with past treated aneurysms, or of relatives. Three subjects have been screened so far for that purpose; in one a small aneurysm has been found, and confirmed angiographically.

Ectasia and fenestration of the anterior cerebral artery associated with persistent trigeminal artery: case report.

Multiple vascular anomalies in a 22-year-old patient who had signs and symptoms of vestibulocochlear dysfunction are reported. Angiography revealed a fenestration of the proximal segment of the left anterior cerebral artery, an ectasia of the left anterior and posterior cerebral arteries, and a persistence of the right trigeminal artery. The rarity of the association is documented, and the clinical significance is discussed.

Intradural extramedullary tuberculoma of the cervical spine. Case report.

A case is reported of a 45-year-old man who developed quadriplegia following a trivial motor-vehicle accident. Investigation including computerized tomography (CT) of the cervical spine revealed a large calcified lesion displacing the spinal cord and nerve roots, which proved to be a tuberculoma. The case is unusual in regard to the age of the patient, the size, location, and nature of the lesion, the mode of presentation, and the delineation of the lesion by CT scanning.

Clinical course and outcome of severe head injury in Australia.

The records of 159 severely head-injured patients (all in coma for longer than 6 hours) from Sydney, Australia, were studied. The clinical course, charted over a 2-week period, indicated that 60% of deaths occur by Day 3 and that 12% of patients remain in coma (Glagow Coma Scale (GCS) score less than 7) for more than 2 weeks. Overall, at long-term follow-up review more than 2 years after injury, 51% of patients were dead, 7% were severely disabled or vegetative, and 42% had a good to moderate recovery. Outcome of the patients in prolonged coma was assessed separately, with only one-third making a good or moderate recovery; two-thirds of the severely disabled patients came from this group. The high proportion of poor outcomes associated with prolonged coma suggests that this group of patients should be specifically targeted in research. One appropriate intervention with this group would be the restructuring and intensification of early rehabilitation. However, the GCS score lacks the precision needed for this type of study, and a better measure of recovery should be developed.

Double-blind, randomized, vehicle-controlled study of high-dose tirilazad mesylate in women with aneurysmal subarachnoid hemorrhage. Part I. A cooperative study in Europe, Australia, New Zealand, and South Africa.

OBJECT: Findings from previous multicenter clinical trials have suggested that tirilazad mesylate, a synthetic nonhormonal 21-aminosteroid, might be effective in preventing delayed cerebral ischemia following subarachnoid hemorrhage (SAH). This beneficial effect, however, was greater in males than females, possibly because of gender-related pharmacokinetic differences. The authors sought to assess the effects of administering a larger dose of tirilazad in women with SAH. METHODS: To test the efficacy of a higher tirilazad mesylate dose in female patients, a prospective randomized, double-blind, vehicle-controlled trial was conducted at 56 neurosurgical centers in Europe, Australia, New Zealand, and South Africa. Eight hundred nineteen patients were randomly assigned to receive either 15 mg/kg/day of tirilazad mesylate or a placebo containing the citrate vehicle. The two groups were similar in prognostic factors for delayed cerebral ischemia and overall outcome. High-dose tirilazad appeared to be well tolerated because no differences in the incidence of untoward medical events were noted between the two groups. Medical and surgical interventions were no different in the two treatment groups except for hyperdynamic therapy (intentional hypervolemia, induced hypertension, and/or hemodilution), which was more often used in the placebo-treated group to counteract symptomatic vasospasm (24% of patients given placebo compared with 18% of patients given tirilazad, p = 0.02). Mortality rates and overall outcome, assessed using the Glasgow Outcome Scale at 3 months post-SAH, were not different between the two groups, despite a significantly lower incidence of delayed cerebral ischemia in patients given tirilazad. Post hoc subgroup analysis by neurological grade also did not reveal significant differences in outcome, although a trend toward a lower mortality rate favoring the study drug was present in patients with neurological Grade IV and V at admission (32% compared with 37%). Symptomatic vasospasm occurred in 33.7% of the placebo-treated patients as opposed to 24.8% of the patients who were given tirilazad (p = 0.005). The severity of symptomatic vasospasm was also attenuated by administration of the study drug (severe symptomatic vasospasm was reported in 11% of the placebo-treated patients compared with 6% of patients in the tirilazad-treated group (p = 0.008). Clinical cerebral infarction from vasospasm was also reduced from 13% in the vehicle-treated group to 8% in the tirilazad-treated group (p < 0.04). CONCLUSIONS: The authors conclude that high-dose tirilazad mesylate is well tolerated in women with aneurysmal SAH. Although a significant reduction in the incidence of symptomatic vasospasm was observed in the treatment group, the primary end point (mortality rate at 3 months post-SAH) was not affected by the study drug. The use of other potentially effective rescue therapies (that is, hypervolemia, hemodilution, and induced hypertension) to counteract vasospasm may have been responsible for these contrasting observations between the two groups.

Transcranial Doppler ultrasound in brain death: experience in 140 patients.

The interpretation of clinical tests for brain death is often complicated by the presence of facial trauma, or the use of barbiturate therapy for reduction of intracranial pressure. We propose a non-invasive technique--transcranial Doppler (TCD) sonography for the diagnosis of brain death. One hundred and forty comatose patients, 111 of whom were believed to be brain dead underwent TCD examinations. TCD assessments of the middle cerebral arteries (MCAs) and the basilar artery were performed before formal clinical testing for brain death. The TCD spectra recorded in the brain dead (BD) patients consisted of short, sharp systolic peaks followed by retrograde flow during diastole or just systolic peaks with absent flow in either direction. There were no survivors among patients who displayed these two TCD patterns. The 29 comatose control patients always showed flow throughout the cardiac cycle--no retrograde flow was ever recorded in these patients all of whom survived. Of particular interest were the basilar artery results. In nine BD patients no MCA signals could be obtained while good quality signals were recorded from the basilar artery. The TCD results agreed essentially with 100% accuracy with clinical testing and four vessel cerebral angiography. This paper illustrates the usefulness of TCD examination of the MCAs and especially the basilar artery in the diagnosis of brain death.

Intracranial pressure changes following primate subarachnoid haemorrhage.

In 29 anaesthetized baboons avulsion of a small intracranial artery was used to produce a subarachnoid haemorrhage, in a closed-skull situation. Intracranial pressure was measured by extradural transducers, and arterial pressure was also measured continuously, with periodic measurements of cerebral blood flow. After haemorrhage there was an immediate fall in cerebral perfusion pressure in nearly all cases, reaching zero in 9 animals. In 18 there was a significant pressor response in the systemic circulation, but perfusion pressure usually remained low in spite of this response. Perfusion pressure recovered after a few minutes in most cases. In the 19 cases where intracranial pressure was measured on both sides, differences occurred in 11, with the higher pressure always on the same side as the haemorrhage. The difference was evident very soon after haemorrhage in 9 cases, and lasted over half an hour in 5 of them. The mechanism of arrest of bleeding was, in most of this series, not that of a zero perfusion pressure. Explanations for this and for the occurrence of differential pressures are discussed.

The use of transcranial Doppler sonography in the diagnosis of brain death.

The diagnosis of brain death is important for many reasons. Clinical testing may not be feasible, so that cerebral angiography is needed to confirm circulatory arrest. Angiography is, however, cumbersome and expensive. We present the results of transcranial Doppler (TCD) studies on the middle cerebral arteries of 40 patients with brain death. In six, no cranial signals could be obtained. All except two of the remaining patients had typical TCD appearances, with a reverberating pattern and little or no net forward flow. One patient had this appearance on one side and a carotid-cavernous fistula on the other side, and another had preserved middle cerebral artery flow. Sixteen control patients all had quite different signals, with some showing evidence of raised intracranial pressure and some of vasospasm. There were thus few false-negative results, and more importantly no false-positives. Refinement of this technique, especially looking to a numerical value for the net flow velocity below which circulatory arrest is certain, is needed. The possibility of a changing pattern on serial studies, with prediction of brain death before it actually occurs, is also to be explored.

Treatment of intracranial aneurysms by combined proximal ligation and extracranial-intracranial bypass with vein graft.

Seven patients with internal carotid artery aneurysms, and one patient with a middle cerebral artery aneurysm, were managed by combining proximal ligation with an extracranial-intracranial bypass procedure. Five bypasses were done with an interposed vein graft between the external carotid artery and the distal middle cerebral artery (vein graft), and three were superficial temporal-middle cerebral artery bypasses (superficial temporal artery grafts). As demonstrated in postoperative angiograms, all eight patients had patent bypasses with nonfilling of the aneurysm. One patient developed transient dysphasia, but there were no permanent neurological deficits associated with carotid occlusion. Four patients had resolution of their neurological problems, and another three patients improved. The distribution of flow from vein grafts is more extensive than from superficial temporal artery grafts. This offers increased protection against ischemia, and increases the likelihood of internal carotid artery aneurysm thrombosis by reducing the turbulence in the distal internal carotid artery.

Giant intracranial aneurysms: diagnosis, management, and outcome.

The diagnosis, management, and outcome of a consecutive series of 25 patients with giant intracranial aneurysms are presented. Symptoms and signs directly or indirectly attributable to the intracranial mass effect accounted for presentation in 16 (64%) patients of whom seven had no focal neurological deficits. Nine patients (36%) presented after subarachnoid hemorrhage. Subarachnoid hemorrhage was frequently associated with intraventricular or intracerebral hemorrhage, a poor clinical grading at admission, and a high mortality (67%). Computed tomographic features of the giant aneurysms were usually characteristic; however, angiography was particularly useful in those in close proximity to the skull base. Nineteen patients had a surgical procedure directly or indirectly aimed at obliteration, isolation, or reinforcement of the giant aneurysm. Successful surgical obliteration or occlusion was obtained in 12 (63%) patients, while seven (37%) had only reinforcement or exploration of the aneurysm. The mortality associated with definitive surgical treatment was 5.6%, and major morbidity occurred in 17%. The good long-term outcome in 75% of the patients after occlusion of the giant aneurysm contrasted with the continuing mortality (43%) and morbidity (43%) in those patients in whom surgical obliteration of the aneurysm was not attained. Although advances in microsurgical instrumentation, anesthetic techniques, and innovative revascularization procedures have facilitated the surgical management of giant aneurysms, significant improvement in the high overall mortality associated with these aneurysms (36% in this series) will probably only be attained by diagnosis of giant intracranial aneurysms before they bleed.

Spiral CT scanning in the detection and evaluation of aneurysms of the Circle of Willis.

PURPOSE: To assess the utility of spiral computed tomography (CT) with three-dimensional reconstruction in defining aneurysms of the Circle of Willis. METHODS: Eighty-one patients with angiographic or surgical correlation were studied between 1993 and 1995, with surface rendered reconstructions of the arteries of the Circle of Willis. RESULTS: Spiral CT was useful in six clinical situations: further assessment in cases with CT suspicion of an aneurysm, follow-up of known untreated aneurysms or aneurysm remnants, subarachnoid hemorrhage (SAH) with negative angiography, a past or family history of aneurysms, and improved definition of aneurysm anatomy. Ten of fifteen patients with previous surgery had no significant artifacts on the spiral study. In 66 other patients studied in search of aneurysms, the sensitivity of detection was 95% and specificity 74%. Seventeen of nineteen aneurysms 3 mm or less in size and 38 of 39 larger were detected by spiral CT. Four of thirteen patients with SAH and previous negative angiography had aneurysms identified, which were confirmed at surgery. CONCLUSIONS: There is great promise in the use of spiral CT in demonstrating aneurysms of the Circle of Willis, including very small ones. Careful detailing of scan protocols and meticulous examination of multiplanar images are needed for maximum accuracy.

A review of cerebral vasospasm in aneurysmal subarachnoid haemorrhage Part II: Management.

This review examines prevention and treatment of delayed cerebral vasospasm after aneurysm haemorrhage, with emphasis on techniques for removal of cisternal blood, fluid loading and induced hypertension, and calcium antagonists. Most effective were fluids/hypertension and nimodipine, which reduced the incidence of DID by over half. Other drugs that may be useful are tissue plasminogen activator and the aminosteroids. A number of others have also been examined. For the treatment of DID, calcium antagonists, and fluid loading and hypertensive treatment are the most effective. Transluminal angioplasty is also proving to be useful. The combination of prophylaxis and treatment with fluids and nimodipine should reduce poor outcome resulting from vasospasm by two-thirds, from 21% untreated to less than 7%. In spite of the more or less proven efficacy of these measures, large numbers of cases are still being reported in whom no specific management is being used.

A review of cerebral vasospasm in aneurysmal subarachnoid haemorrhage Part III: Mechanisms of action of calcium antagonists.

The possible mechanisms by which calcium antagonists are effective in the management of cerebral vasospasm are discussed. They number seven: relaxation of spastic arteries or prevention of spasm; opening up of collateral channels; neuronal protection at the membrane level; intracellular actions in neurones or vascular cells; alterations of blood rheology; antimitogenic effects; and improved fluid management of patients. A number of more minor actions may also be involved. It is likely that more than one mechanism is involved in their protective effect, especially at different periods in the time course of vasospasm.

A review of cerebral vasospasm in aneurysmal subarachnoid haemorrhage Part I: Incidence and effects.

Delayed ischaemia due to cerebral 'vasospasm' is a significant cause of morbidity and mortality after aneurysm haemorrhage. In a literature review more than 30 000 cases were found where vasospasm after subarachnoid haemorrhage (SAH) was discussed. The incidence of angiographic vasospasm was 43.3% overall, and 67.3% where angiography was done at a time of maximum expected spasm. Symptomatic vasospasm or delayed ischaemic deficit (DID) occurred in 32.5%. There was no difference in incidence and time course between preoperative and postoperative cases. 30% of those with DID died, and permanent neurological deficits occurred in 34%. A fatal outcome was much more likely in the presence of vasospasm, and a satisfactory outcome one third less likely. Vasospasm is thus the cause of death in about 10%, and of disability in slightly more cases of aneurysmal SAH. The extent of the problem has not changed significantly over three decades.

The importance of traumatic subarachnoid haemorrhage.

Post-traumatic cerebral vasospasm is being increasingly recognised as a possibly significant complication after head injury. To assess the relationship between post-traumatic subarachnoid haemorrhage (tSAH) and post-traumatic vasospasm, 63 patients with severe head injury (GCS 3-8) were studied. Forty-seven patients had cerebral contusion on the initial CT scan. In 25 of these (Group I) there were only contusions, while 22 (Group II) also had tSAH. All patients had daily measurements of blood flow velocity in the basal cerebral arteries using transcranial Doppler ultrasound (TCD). The incidence of vasospasm detected by TCD was significantly higher in Group II. Furthermore there were significantly fewer good outcomes (GOS 1 and 2) in this group. These results suggest that the presence of subarachnoid blood in patients with severe head injury is associated with a risk of vasospasm, and with poorer outcome.

A review of cerebral vasospasm. Part IV. Post-traumatic vasospasm.

Cerebral vasospasm is increasingly recognized as contributing to ischaemia after head injury. The reported incidence of post-traumatic vasospasm (PTV) varies between 10% and 90%, probably largely because of differences in patient selection, in definitions of vasospasm and in methods of detecting spasm. In severe head injury, based on studies with similar criteria, the incidence is approximately 40%. PTV is often associated with traumatic subarachnoid haemorrhage (tSAH), but has been reported without tSAH. These two factors are independently associated with poor outcome, but the direct links between tSAH, vasospasm and outcome are uncertain. There is evidence that calcium antagonists improve outcome in patients with head injury and tSAH; aminosteroids may also be effective here. Other strategies such as maintaining normocapnia and control of blood volume and pressure may also be useful. Further investigation of large cohorts is required to clarify fully the significance of PTV, its relationship with tSAH and outcome and possible treatment modalities.

Aplasia of the posterior arch of the atlas.

A case of aplasia of the posterior arch of the atlas with persistence of the posterior tubercle in a 14-year-old youth is presented. The pathogenesis and clinical implications of the condition are discussed.