Our experience with 30 cases of atlanto-axial dislocation, over the period of 3 years and 9 months, is described A modified plate and screw method of fixation of the lateral masses of the atlas and axis was successfully used in these cases The technical aspects and merits of the method, wherein a 100% union rate was achieved, with no morbidity, mortality, or instrument fatigue or failure, are presented The average follow-up period is of 19 months The technique provided immediate rigid segmental internal fixation, permitting early mobilization with minimal external support Onlay and interfacetal bone grafts subsequently produced bony fusion Direct application of screws to the atlas and axis, thus utilizing the firm purchase in their thick and large cortico-cancellous lateral mass, provides a biomechanically strong fixation of the region Occipito-cervical fusion can be achieved in selected cases by a modification of the method It appears that such a method of fixation could be useful at least in some complex congenital or traumatic craniovertebral region instability where the conventional methods have failed or are not suitable

Plate and screw fixation for atlanto-axial subluxation.

Reversible cerebral vasoconstriction syndromes (RCVS) comprise a group of diverse conditions, all characterized by reversible multifocal narrowing of the cerebral arteries heralded by sudden (thunderclap), severe headaches with or without associated neurologic deficits. Reversible cerebral vasoconstriction syndromes are clinically important because they affect young persons and can be complicated by ischemic or hemorrhagic strokes. The differential diagnosis of RCVS includes conditions associated with thunderclap headache and conditions that cause irreversible or progressive cerebral artery narrowing, such as intracranial atherosclerosis and cerebral vasculitis. Misdiagnosis as primary cerebral vasculitis and aneurysmal subarachnoid hemorrhage is common because of overlapping clinical and angiographic features. However, unlike these more ominous conditions, RCVS is usually self-limited: Resolution of headaches and vasoconstriction occurs over a period of days to weeks. In this review, we describe our current understanding of RCVS; summarize its key clinical, laboratory, and imaging features; and discuss strategies for diagnostic evaluation and treatment.

Narrative review: reversible cerebral vasoconstriction syndromes.

The microsurgical anatomy of the middle cerebral artery (MCA) was defined in 50 cerebral hemispheres. The MCA was divided into four segments: the M1 (sphenoidal) segment coursed posterior and parallel to the sphenoid ridge; the M2 (insular) segment lay on the insula; the M3 (opercular) segment coursed over the frontoparietal and temporal opercula; and the M4 (cortical) segment spread over the cortical surface. The Sylvian fissure was divided into a sphenoidal and an operculoinsular compartment. The M1 segment coursed in the sphenoidal compartment, and the M2 and M3 segments coursed in the operculoinsular compartment. The main trunk of the MCA divided in one of three ways; bifurcation (78% of hemispheres), trifurcation (12%), or division into multiple trunks (10%). The MCA's that bifurcated were divided into three groups: equal bifurcation (18%), inferior trunk dominant (32%), or superior trunk dominant (28%). The MCA territory was divided into 12 areas: orbitofrontal, prefrontal, precentral, central, anterior parietal, posterior parietal, angular, temporo-occipital, posterior temporal, middle temporal, anterior temporal, and temporopolar. The smallest cortical arteries arose at the anterior end and the largest one at the posterior end of the Sylvian fissure. The largest cortical arteries supplied the temporo-occipital and angular areas. The relationship of each of the cortical arteries to a number of external landmarks was reviewed in detail.

Microsurgical anatomy of the middle cerebral artery

Both HIV infection and methamphetamine dependence can be associated with brain dysfunction. Little is known, however, about the cognitive effects of concurrent HIV infection and methamphetamine dependence. The present study included 200 participants in 4 groups: HIV infected/methamphetamine dependent (HIV+/METH+), HIV negative/methamphetamine dependent (HIV−/METH+), HIV infected/methamphetamine nondependent (HIV+/METH−), and HIV negative/methamphetamine nondependent (HIV−/METH−). Study groups were comparable for age, education, and ethnicity, although the HIV−/METH− group had significantly more females. A comprehensive, demographically corrected neuropsychological battery was administered yielding a global performance score and scores for seven neurobehavioral domains. Rates of neuropsychological impairment were determined by cutoff scores derived from performances of a separate control group and validated with larger samples of HIV+ and HIV− participants from an independent cohort. Rates of global neuropsychological impairment were higher in the HIV+/METH+ (58%), HIV−/METH+ (40%) and HIV+/METH− (38%) groups compared to the HIV−/METH− (18%) group. Nonparametric analyses revealed a significant monotonic trend for global cognitive status across groups, with least impairment in the control group and highest prevalence of impairment in the group with concurrent HIV infection and methamphetamine dependence. The results indicate that HIV infection and methamphetamine dependence are each associated with neuropsychological deficits, and suggest that these factors in combination are associated with additive deleterious cognitive effects. This additivity may reflect common pathways to neural injury involving both cytotoxic and apoptotic mechanisms. (JINS, 2004, 10, 1–14.)Note: Dr. Erin D. Bigler served as action editor during the course of this review.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1355617704101021

Methamphetamine dependence increases risk of neuropsychological impairment in HIV infected persons.

Vasoconstriction is not recognized as a cause of cerebrovascular disease except in the vasospasm seen following subarachnoid hemorrhage and possibly in migraine. However, we found four patients to have transient, fully reversible vasoconstriction and dilatation prominently involving arteries around the circle of Willis. All four patients were evaluated for severe headaches and fluctuating or recurring motor or sensory deficits. No cause for the clinical syndromes and angiographic abnormalities was found. Similar patients are reported in the literature under various nosologies. This newly recognized clinical-angiographic syndrome should be differentiated from other known causes of vessel constriction and dilatation; the precipitants of reversible vasoconstriction may then be better defined.

Reversible cerebral segmental vasoconstriction.

The cerebral angiographic findings in 19 drug abuse patients are presented. Many larger and intermediate-size arteries showed irregular segmental areas of constriction with changes of caliber and contour of the vessel walls. Many arteries with diameter of 1 mm or less demonstrated complete or partial occlusions. Some occlusive changes have an appearance suggestive of embolic phenomena, but it is possible the changes are due primarily to vasculitis and secondary thrombus formation. Which drugs or combination of drugs are responsible for these changes is unknown, as is the role of impurities in the drugs and sepsis.

Cerebral angiographic changes in the drug abuse patient.

The middle cerebral artery has been noted to demonstrate anomalies less frequently than the other major intracranial arteries.The cerebral angiograms and brief case histories of 7 patients with anomalies involving the middle cerebral artery are presented. Three cases of accessory middle cerebral artery, 2 cases of duplication of the middle cerebral artery, and 2 cases of early bifurcation of the middle cerebral artery are reported.

Anomalies of the middle cerebral artery: accessory artery, duplication, and early bifurcation

Five adult Rhesus monkeys were given intravenous methamphetamine during a two-week period and then sacrificed. Immediately following injection, 3 animals showed decreased caliber of some of the small cerebral arteries with slow flow or absence of flow in some vessels. In 2 animals severe generalized arterial spasm developed during the two-week period. All 5 animals at necropsy demonstrated extensive brain damage. There were focal areas of ischemia and infarction and generalized areas of cerebral edema and ischemic nerve cell changes. The drug dose was in the range followed by some addicts.

Cerebral vascular changes secondary to amphetamine abuse in the experimental animal.

Anomalous branches of the internal carotid artery are rarely demonstrated angiographically. Cases of the ascending pharyngeal, occipital, Vidian (pterygoid canal), and posterior inferior cerebellar arteries arising from the internal carotid artery are presented. A case of anomalous origin of the anterior cerebral artery from the internal carotid artery at the level of origin of the ophthalmic artery is also described. Brief embryological explanations of the vascular anomalies are given.

Anomalous Branches of the Internal Cartoid Artery

Fenestration or partial duplication of intracranial arteries is noted occasionally during anatomical dissection. Since the phenomenon is rarely described in the literature, the authors present 5 recently observed cases, with a brief explanation of the proposed embryology and potential clinical significance.

Bergeron Rt

Papers

Cerebral angiographic changes in the drug abuse patient.

Anomalies of the middle cerebral artery: accessory artery, duplication, and early bifurcation

Cerebral vascular changes secondary to amphetamine abuse in the experimental animal.

Anomalous Branches of the Internal Cartoid Artery

Angiographic demonstration of fenestrations of the intradural intracranial arteries.