Biomedical subjects
Publications and source records attributed to R M Crowell.
A patient with trigeminal neuralgia caused by a tortuous and ectatic vertebrobasilar artery is presented. He was treated with microvascular decompression using a fine silicone sling sutured to the dura over the petrous pyramid. The technical details are described.
The management of patients with cavernous angioma continues to evolve. Our current recommendations for management are as follows. 1. Patients who are asymptomatic are observed. 2. Patients with acute severe or progressive neurological deficits are operated upon. 3. Patients presenting with a seizure are usually operated upon but some are observed, depending on the factors discussed. 4. Patients with a single hemorrhage in the cerebrum, cerebellum, or spinal cord are usually operated upon. When the hemorrhage is in the brainstem, thalamus, or basal ganglia, they are observed. 5. Patients with a recurrent hemorrhage are usually operated upon but there are exceptions when the lesion is in a deep area with high surgical risk.
Radiological and clinical analysis was performed in 5 patients with posterior fossa dural arteriovenous fistulas (DAVFs) with isolated sinus segment due to sinus thrombosis, and their patho physiological, diagnostic, and therapeutic concerns were discussed. Patients ranged in age from 36 to 73 years old with a mean of 57 years and included 2 males and 3 females. Two patients presented with ataxia, one with ataxia and bruit, one with atypical facial pain, and one with parietal dysfunction. One patient had a history of hemorrhagic event. DAVFs were located at transverse-sigmoid sinus (3 cases), superior petrosal sinus (1 case), and straight sinus (1 case). They were fed by many branches of external carotid artery including middle meningeal artery, ascending pharyngeal artery, posterior auricular artery, occipital artery, meningeal branches of vertebral artery and posterior cerebral artery, and meningohypophyseal trunk of internal carotid artery. Shunt flow drained into contralateral transverse-sigmoid or supratentorial sinuses via the isolated venous segment through markedly dilated cortical and/or deep venous systems, which caused altered normal venous drainage pattern and venous hypertension. Transarterial embolization in multiple stages (mean 3.4) using n-butyl cyanoacrylate (NBCA) could alleviate symptoms in all cases. DAVFs were almost totally obliterated in 3 patients. Further embolization in one case, and surgical excision in one case were planed because of some residual dilated cortical venous drainage. Posterior fossa DAVFs with isolated sinus segment accompany markedly dilated cortical and/or deep venous systems. They could cause cerebellar, brainstem, or cranial nerve dysfunctions, and sometimes present distant supratentorial symptoms or hydrocephalus due to abnormal venous drainage and venous hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
The diagnosis of central nervous system hemangioblastoma as well as the surgical treatment requires the accurate radiologic visualization of both the cystic and solid components of the tumor. We report two cases of posterior fossa hemangioblastoma examined with gadolinium-diethylenetriaminepentaacetic acid-enhanced magnetic resonance imaging, which clearly defined the tumor nodule that was not visualized on noncontrast magnetic resonance imaging, contrast-enhanced computed tomography scans, or angiography. In both cases the operative findings precisely correlated with the gadolinium-enhanced magnetic resonance image. Gadolinium-enhanced magnetic resonance imaging is the examination of choice for preoperative evaluation of posterior fossa hemangioblastoma. In cases of von Hippel-Lindau syndrome, magnetic resonance imaging is a useful tool for clinical screening as well as follow-up.
In an attempt to find safe and effective methods of treating giant intracranial aneurysms, we have developed a one-step construction of giant experimental aneurysms in dogs with a yield of 100% patency of the parent artery and the experimental aneurysm without intraaneurysmal thrombus. Giant aneurysms were produced in the right thrombus. Giant aneurysms were produced in the right common carotid artery of nine mongrel dogs. Key features concerning the procedure were: (1) proximal placement of the aneurysmal neck, (2) 1 cm length as the aneurysmal ostea, and (3) postoperative aspirin therapy. This one-step construction of giant experimental aneurysms in dogs should prove helpful in evaluating a wide variety of treatment modalities of giant aneurysms in the laboratory. It also may be of additional value in investigative studies relative to catheters, balloons, and other similar techniques.
We report a case of a fatal rupture of a previously unruptured giant aneurysm of the bifurcation of the internal carotid artery (ICA), which occurred after an extracranial-intracranial (EC-IC) bypass and the partial occlusion of the ICA. Interim angiography showed retrograde filling of the proximal middle cerebral artery to the aneurysm. There have been four previously reported cases of giant aneurysms rupturing after treatment with an EC-IC bypass and carotid ligation, and it appears likely that a change in pressure/flow dynamics produced by the bypass may have been the cause. The technique of carotid ligation with an EC-IC bypass is used frequently to treat unclippable intracranial aneurysms, and the resulting hemodynamic changes need to be considered carefully to prevent this type of complication. To minimize hemodynamic stress on the aneurysm, we suggest that 1) the bypass caliber should be as small as possible consistent with sufficient cerebral blood flow after ICA occlusion, and 2) complete ICA occlusion should be performed as soon as possible after the bypass.
Dissection of the cervicocranial arteries is becoming more frequently recognized as a cause of neurological disorders. Typical clinical features seen with dissection include unilateral headache, oculosympathetic palsy, amaurosis fugax, and symptoms of focal brain ischemia. The diagnosis of carotid or intracranial dissection is usually best confirmed by angiography, although magnetic resonance imaging and computed tomography have been shown to visualize intimal dissection. The prognosis in cases of spontaneous dissection is generally benign unless the initial manifestation involves infarction with substantial deficit. The best approach to treatment appears to be the administration of the anticoagulant, heparin, followed by warfarin or antiplatelet therapy. Surgical intervention is reserved for cases of progressive or recurrent ischemic complication that occurs despite the administration of adequate doses of anticoagulants.
Two cases of saccular intracranial aneurysms arising from the superior hypophyseal artery take-off from the internal carotid artery are presented. The angiographic findings and technical details of the operative approach are discussed. Particular attention is focused on the use of fenestrated angled clips.
A patient harboring a cerebral arteriovenous malformation (AVM) underwent angiography in an attempt to embolize the AVM. During catheterization (and prior to embolization) he became hemiplegic and aphasic. Angiography revealed a complete middle cerebral artery (MCA) occlusion by an embolus. The patient was treated with recombinant tissue plasminogen activator (t-PA), a thrombolytic agent. Restoration of MCA flow was achieved, and the patient recovered. Immediately after MCA embolus, t-PA infusion may lead to thrombolysis and neurological recovery. The decision-making process as well as the risks associated with the use of t-PA are discussed.
The neurological complications of sickle-cell disease include cerebral intracerebral hemorrhage; subarachnoid hemorrhage (SAH) has been infrequently reported. Among 325 patients with sickle-cell disease followed at the University of Illinois between 1975 and 1989, 11 cases of SAH were identified. Aneurysms were found in 10 of these patients, three of whom had multiple aneurysms. All of the patients had some degree of anemia and nine underwent craniotomy without hematological or neurological complications. From this review it appears that SAH is not uncommon in sickle-cell disease patients and tends to occur at a younger age and with smaller aneurysm size than in the general population. With proper perioperative management, including exchange transfusions to reduce the proportion of hemoglobin S to less than 30%, these patients can undergo angiography and craniotomy without an increased incidence of complications. The techniques used in managing sickle-cell disease patients with SAH are discussed.
A recent modification of the occipital transtentorial approach to the pineal region and medial-posterior hemisphere is described. The patient is operated upon in a lateral reclining (park bench) position with the side to undergo occipitoparietal craniotomy, slightly dependant. Following dural opening to the margins of the superior sagittal and lateral sinuses, gentle traction with a brain spatula facilitates the occipital transtentorial and transfalcine approach to the incisural region. Ventricular or spinal fluid drainage is often helpful. The occipital lobe falls away from the midline and falcotentorial regions by gravity. Absence of occipital parasagittal bridging veins is a helpful feature and careful convexity dural opening allows the occipital lobe to move laterally. Microsurgical treatment of pineal, splenial, falcotentorial and medial posterior hemisphere lesions may be greatly facilitated. Our experience with six cases is presented. To date, published results of this operative approach have been excellent with the risk of hemianopsia, parenchymal venous infarction, and air embolus much lessened or eliminated.
SAH is an important and common form of stroke. Detection of SAH is now possible through the clinical syndrome and CT scanning. Angiography is required to pinpoint the site of the hemorrhage. Medical therapy to prevent complications is often effective. Surgical therapy to prevent recurrent hemorrhage is now effective and safe with modern microsurgical methods. Even with large and deep aneurysms or AVMs, indirect treatment by means of interventional radiology or radiosurgery may be effective in eliminating these life-threatening lesions. In a few cases, evacuation of intraparenchymal brain hematoma can be life-saving. SAH is common, readily identified, and treatable. All physicians should be able to recognize and institute appropriate management for this important subclass of stroke.
Platelet deposition in the microcirculation may play a role in focal cerebral ischemia. We investigated platelet deposition in selected parts of the cat brain after temporary middle cerebral artery occlusion. Ten anesthesized cats were given autologous indium-111-labeled platelets and chromium-51-labeled erythrocytes. The right middle cerebral artery was occluded with miniature aneurysm clips for 3 hours via a transorbital approach; blood pressure was reduced concomitantly to decrease the collateral circulation. Removal of the clips initiated a 45-minute period of normotensive reperfusion. After sacrifice, the brain was removed and sectioned for comparison of right- versus left-hemisphere platelet deposition. Platelets were selectively deposited in the territory of the occluded right middle cerebral artery. Significant deposition was found in the caudate nucleus, internal capsule, parietal cortex, and the centrum semiovale. Our findings support the evidence that platelets are deposited in the microvasculature during temporary severe focal cerebral ischemia.
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Eight patients with atlantoaxial instability secondary to trauma or rheumatoid arthritis were treated with posterior C1-C2 arthrodesis using the Halifax interlaminar clamp and autogenous bone graft or methylmethacrylate. Thus far, with an average follow-up of 6 months, satisfactory stability has been achieved with no instrument failure.
In a patient with multiple intracranial aneurysms, the clinical examination, computed tomographic brain scan, and cerebral angiogram failed to disclose which of five aneurysms had ruptured. Magnetic resonance imaging (MRI) revealed high signal intensity compatible with hemorrhage in the lower portion of one cerebellar tonsil, and a corresponding posterior inferior cerebellar artery aneurysm was successfully obliterated. We would add MRI to the list of useful adjuncts in identifying which of multiple aneurysms bled.
For neuroradiologic evaluation of parasellar lesions, a wide array of examinations may be utilized. CT and MRI are used in the assessment of these lesions to establish the diagnosis and to assist the neurosurgeon in defining the precise location. Careful neuroradiologic assessment and close cooperation between the neurosurgeon and the neuroradiologist have much bearing on the surgical planning and eventual outcome of the patient.
We studied 128 patients admitted over a 12 1/2-year period to the Cook County Hospital Trauma Unit with acute subdural hematoma (ASDH): 82 were admitted directly and 46 were admitted after transfer from another hospital; 59% of the entire group died and only 27% obtained a functional recovery. As a group, the transferred patients, who suffered delays of several hours before receiving definitive surgical care, fared significantly worse than the patients with equivalent trauma who were admitted directly. The mortality of the transferred patients was 76%, compared to 50% of the direct admit patients. The outcome was also worse for transfer patients who experienced a 'lucid interval' or with alcohol intoxication. We conclude that the delays associated with failure to admit patients with ASDH directly to a head trauma center cause an excessive mortality and morbidity which could potentially be avoided by proper triage.