Robert R. Smith

Petrosal approach for petroclival meningiomas.

Thirteen patients harboring large petroclival meningiomas are reported. The evolution of the petrosal approach is discussed, and modifications for improvement in surgical technique are described. There was no mortality in this series, and total removal was achieved in all but two patients. Morbidity included cranial nerve deficit, pulmonary embolism, and hemiparesis.

Orthostatic Hypotension as a Risk Factor for Stroke The Atherosclerosis Risk in Communities (ARIC) Study, 1987–1996

Background and Purpose The association between orthostatic hypotension (OH) and stroke has rarely been investigated in longitudinal studies. The purpose of the present study was to determine whether OH predicts ischemic stroke in a middle-aged, biethnic population after adjustment for known stroke risk factors. Diastolic, systolic, and consensus OH were evaluated for baseline associations and for the ability to predict stroke. Methods In 11 707 persons from the Atherosclerosis Risk in Communities (ARIC) cohort who were free of stroke and overt heart disease at baseline, Cox proportional hazards analyses modeled the association between OH at baseline and incident ischemic stroke over 7.9 years of follow-up. OH was defined as a systolic blood pressure drop ≥20 mm Hg (systolic OH), a diastolic blood pressure drop ≥10 mm Hg (diastolic OH), or a drop in either (consensus OH) when a person changed from a supine to standing position. Results OH was predictive of ischemic stroke, even after adjustment for numerous stroke risk factors (consensus OH: hazard ratio, 2.0; 95% CI, 1.2 to 3.2). While the baseline characteristics associated with OH varied depending on the type of OH, all types of OH had a similar risk of stroke. Conclusions OH is an easily obtained measurement that may help to identify middle-aged persons at risk for stroke.

Results and Complications

Many factors influence results after acute aneurysmal subarachnoid hemorrhage (SAH). The configuration, size, and location of the aneurysm as well as its relationship to intracranial structures are important. The clinicoanatomic form of the hemorrhage and the presence of vasospasm, hydrocephalus, intracranial hypertension, and rebleeding affect the outcome. The age of the patient, the associated systemic pathology, hypertension, heart disease, and other conditions associated with the ictal event (e.g., heart failure) are all significant. Neurological condition is a significant variable but yet an integral part of all other factors.

Arterial wall changes in early human vasospasm

Histological, histochemical, and histoimmunological studies were conducted on cerebral arteries from three living patients with a recent subarachnoid hemorrhage. There seemed to be a correlation between the severity of vasospasm and the magnitude of pathological alterations. Myofibroblasts and Type V collagen within the medial layer were abundant in vessels showing marked constriction, but were less conspicuous in those arteries showing milder involvement. Intracranial arteries from patients who died from noncerebral causes did not demonstrate these changes. Thus, myofibroblasts and Type V collagen may be related to cerebral vasospasm by holding the damaged vessel in a contracted phase for weeks during the healing period.

Surgery of tumors invading the cavernous sinus

Potential injury to neurovascular structures within the cavernous sinus often prohibits total removal of various cranial base tumors. This report discusses the rationale of direct cavernous sinus surgery and describes a surgical technique refinement as evolved from experience in 18 histologically benign operative cases. The nature of tumor extension mandated entry to the sinus, either through the superior or lateral wall or both. The operative microscope facilitated dissecting and preserving the carotid artery and cranial nerves transversing the sinus. Venous bleeding was controlled by packing. There was one death unrelated to cavernous sinus surgery. Five patients, however, had complications related to cavernous sinus surgery, including hemiplegia in one patient and cranial nerve palsy in four.

Lateral Cervical Spine Dislocation and Vertebral Artery Injury

Although anterior and posterior traumatic displacement of cervical vertebrae are commonly noted, and the devastating neurological deficits associated with these injuries have been amply defined, lateral displacement with fractures has been rarely recognized, and the clinical significance of this injury has been overlooked. This report describes five cases of cervical spine fractures with lateral dislocation. All patients had lateral and anteroposterior cervical spine radiographs as well as cervical angiography or postmortem study demonstrating either complete occlusion or significant impairment of flow of the vertebral arteries. Two cases had traumatic vertebral artery occlusion with secondary medullary and cerebellar infarction resulting in the patients death. Vertebral artery injury apparently is not uncommon in this particular type of fracture. The diagnosis of these vascular injuries may require angiography or magnetic resonance angiography. A vertebral occlusion or dissection is a problem of considerable complexity, requiring individualized management depending on the patients symptomatology, location and nature of the injury, and time lapsed since the injury.

An orbitocranial approach to complex aneurysms of the anterior circulation.

A surgical approach to the skull base was developed in cadavers and then used in the treatment of patients with complex aneurysms of the anterior circulation. The operative method involves removal of portions of the orbital rim, orbital roof, and sphenoid bone. By removing the orbital rim and a portion of the orbital roof, multidirectional viewing is possible. This is important when dealing with the anterior aspect of the cavernous sinus and anterior clinoid process, as must frequently be done when isolating the neck of an ophthalmic aneurysm. The optic canal is opened wide and the optic nerve mobilized, allowing resection of the dura propria covering the cavernous carotid artery. Clip placement is performed in an anteroposterior plane, thus lessening the chance for compromise of the internal carotid artery. The low approach alleviates brain retraction and the small flap minimizes brain exposure. The approach also allows preservation of the arterial and neural supply to the frontalis and temporalis muscles, thereby preventing postoperative cosmetic deficits. During the past year and a half, this approach has been employed in 25 patients with difficult aneurysms of the anterior circulation. The difficulties of these cases stemmed from their odd location, size, or complex anatomy. Although periorbital edema may have been more severe during the first postoperative week, overall improved cosmesis was achieved.

The Petrosal Approach: Indications, Technique, and Results

Surgical access to the clivus and petrous apex remains a formidable challenge. Intradural tumours at the clivus and petroclival area are superbly exposed via the petrosal approach described here. To date, we have operated on 33 patients having benign tumours using this approach. Total removal was achieved in all patients except 3 with meningiomas. There was no mortality, morbidity included 1 patient with hemiparesis and several with cranial nerve deficits.

Mechanism of action of balloon angioplasty in cerebral vasospasm.

Recent technical advances in interventional neuroradiology have made it possible to dilate cerebral arteries showing vasospasm after a subarachnoid hemorrhage. Although the reported effects of dilatation in clinical cases have been dramatic, few experimental studies of the mechanism of action have been performed. It also is still unclear why dilated arteries rarely show restenosis. Using the scanning electron microscope, we examined changes in the three-dimensional structure of connective tissues in vessel walls after balloon angioplasty. Femoral arteries from cats and middle cerebral arteries from human autopsies were studied. The vessels were dilated in situ with a balloon catheter until the intimal pressure reached 1.5 Wr 3 atm; then they were fixed and digested with 88% formic acid. The specimens were freeze dried and observed under the scanning electron microscope. Normal vessels without balloon dilatation were treated in the same manner and used as controls. The results showed that the normal structure of collagen fibers in the vessel walls was affected significantly by balloon dilatation. Stretched and torn fibers were observed frequently when 3 atm were applied. We concluded that the long-lasting effects of balloon dilatation may be caused by the disruption of connective tissues that proliferate in the vessel wall after a subarachnoid hemorrhage.

The angiopathy of subarachnoid hemorrhage: angiographic and morphologic correlates.

In patients with subarachnoid hemorrhage, particularly hemorrhage due to aneurysmal rupture, there was a positive significant relation between angiographic vessel constriction and vessel pathology (angiopathy). Furthermore, there was a positive relationship between post-hemorrhage survival time and the severity of angiopathy. Factors such as age, sex, operations, steroid and CSF pressure seemed to have little affect on angiopathy following hemorrhage. Pathological changes were primarily limited to the involved major cerebral vessels themselves, with their branches rarely being affected. While intramural vascular hemorrhage was a common pathological feature in vessels showing severe pathology, the mere presence of blood surrounding an artery seemed to have little influence on vessel alterations.