Collagen nerve guide tubes in the rat septohippocampal pathway.

Synthetic porous collagen tubes were implanted into the rat fimbria in order to determine whether such prostheses will permit axonal growth in the mature mammalian central nervous system (CNS). The tubes were found to slowly degrade over 4 weeks. In the majority of cases a distinct tissue core occupied the lumen of the tube and extended from the rostral (septal) end to the caudal (hippocampal) end. The core consisted of cellular aggregates of various cell types and blood vessels. In addition, the presence of axons within the tube lumen was demonstrated at both light and electron microscopic levels. Fibers within the tubes were visualized with noradrenergic histofluorescence and with neurofilament immunohistochemistry. Pretreatment of the tubes with nerve growth factor (NGF) resulted in circumferential disposition of the tissue core and an increase in acetylcholinesterase activity associated with the tube but no obvious change in axonal regeneration. No evidence was obtained for reinnervation of the hippocampal formation by cholinergic or noradrenergic fibers. These results indicate that porous collagen tubes will persist for several weeks within the mature rat CNS and can support axonal growth.

Concurrent intradural and extradural meningiomas of the cervical spine.

A case of an extradural spinal meningioma presenting with a separate intradural meningioma at the same cord level is reported. Review of the English literature on spinal epidural meningiomas reveals a high incidence of concurrent intradural tumors in patients with epidural meningiomas. This leads to the conclusion that the intradural space should be evaluated carefully when an epidural meningioma is encountered.

Surgical management of brain stem vascular malformations.

Vascular malformations of the brain stem are a histologically heterogenous collection of lesions which most often present with sudden and progressive neurologic deficit related to haemorrhage. Since 1987 the authors have treated eleven cases of brain stem vascular malformation. Seven of the patients were treated with complete surgical extirpation of the haematoma and malformation because of progressive neurologic deficit. Four additional patients made a full neurologic recovery and are being carefully observed for signs suggestive of the need for surgical treatment. Complete surgical excision of brain stem vascular malformations is mandatory for patients with progressive neurologic deficit related to recurrent haemorrhage.

Diagnosis and treatment of vascular brain-stem malformations.

Vascular malformations are a common cause of spontaneous brain-stem hemorrhage in young normotensive individuals. These lesions are no longer cryptic. Magnetic resonance (MR) imaging has renewed interest in the treatment of this disorder because of the precise accuracy in diagnosis and localization of these lesions that it affords. The MR image demonstrates characteristic findings of multiple hemorrhages of varying ages surrounded by a hypointense peripheral zone of hemosiderin. Five cases of vascular brain-stem malformation diagnosed with MR imaging are described. The vascular malformations could be demonstrated as "flow void" areas in three cases. Three patients were treated surgically and vascular malformations were confirmed: all three patients improved postoperatively. Two patients were treated nonsurgically; one of these recovered from a second hemorrhage and the other experienced neurological deterioration after a single hemorrhage. High-energy radiotherapy was not effective for the one vascular malformation treated by this method. This experience suggests that surgical exploration should be considered for vascular brain-stem malformations when the diagnosis is confirmed by MR criteria and the clinical course and lesion are both progressive in character.

Repair of spinal dural defects with vicryl (polyglactin 910) mesh.

This study examined and compared the effectiveness of woven vicryl (polyglactin 910) mesh and lyophilized cadaver dura (Lyodura) for the repair of spinal dural defects. A woven vicryl mesh was used to repair spinal dural defects in 16 mongrel dogs. As an internal control, all animals had a separate dural incision that was closed with 9-0 vicryl suture. Animals were killed, and results were evaluated at 4, 8, 12, and 24 weeks. The repair of dural defects was achieved in all animals, and there were no cases of pseudo-meningocele formation, cerebrospinal fluid leakage, or postoperative infection. The vicryl mesh served as a latticework for formation of a neodural membrane. Inflammatory or reactive response to vicryl mesh was minimal, and no adhesion to underlying neural structures was noted. The neodural membrane formed in the animals in which lyophilized dura was employed was usually thicker than those in which vicryl mesh was used and was associated with thick arachnoid-neural adhesions in two of eight animals. We believe vicryl mesh is a suitable dural substitute and offers promise for use in clinical situations.

Multiple intracranial aneurysms in identical twins.

Familial intracranial aneurysms are well documented, with the highest association occurring among siblings. Five pairs of identical twins with subarachnoid hemorrhage have been previously reported. We present the sixth set of identical twins with multiple aneurysms. These cases represent the first report in the literature of multiple mirror aneurysms in identical twins. One twin presented with subarachnoid hemorrhage. Her sister, who was asymptomatic, had elective angiography which demonstrated multiple aneurysms in locations identical to her sister's aneurysms. In families in which a twin presents with subarachnoid hemorrhage, it is appropriate to recommend angiography to the asymptomatic twin.

Management of inoperable cerebral aneurysms by the navigational balloon technique.

Intravascular navigation with nondetachable balloons is a safe, effective method of treatment for inaccessible aneurysms of the internal carotid artery. The rate of ischemic complications is lower than that associated with carotid ligation, and the rate of subsequent hemorrhage is lower than that associated with either carotid ligation or direct clipping. Therefore, for many internal carotid artery aneurysms that originate at or proximal to the ophthalmic artery, the nondetachable balloon technique is an alternative treatment choice. During a 7-year period, 21 aneurysms of the internal carotid artery were treated by the nondetachable balloon technique. All 21 aneurysms were successfully excluded from the circulatory system by either proximal occlusion or trapping of the aneurysm neck. This series consisted of 8 carotid-ophthalmic artery aneurysms, 11 carotid-cavernous aneurysms (6 spontaneous, 5 traumatic), 1 petrous segment aneurysm, and 1 cervical segment aneurysm. At 3 years of follow-up, the following incidences were noted: transient ischemia, 4.7%; infarction, 9.6%; and hemorrhage, 0%. The complications were 1 case of transient hemiparesis and 2 late ischemic events. Fifty per cent of the patients underwent follow-up computed tomography, and thrombosis of the aneurysm was confirmed in all except one case, which was partially thrombosed.