Organization of spinal inputs to the perihypoglossal complex in the cat.

First- and second-order spinal afferents to the perihypoglossal complex were sought by using axonal transport of WGA-HRP. Injections in C1, 2, and 3 dorsal root ganglia resulted in axonal labeling in the nucleus intercalatus and the external cuneate nucleus, with a number of retrogradely labeled cells seen as well in the latter. A similar pattern of axonal labeling in the nucleus intercalatus as well as several retrogradely labeled cells were found after spinal cord injections at levels C1, 2, and 3. A prominent field of labeled axons was also present in the rostral main cuneate nucleus. No labeling was seen in the perihypoglossal nuclei after injections in the spinal cord or dorsal root ganglia at levels caudal to C3. After injections of HRP into the perihypoglossal nucleus we were able to identify labeled neurons within Rexed's laminae V-VIII and the central cervical nucleus. Anterograde labeling in the main cuneate nucleus was observed after C1 to C5 ganglion and C1 to C6 cord injections. The pattern and extent of labeling in the perihypoglossal nuclei and adjacent structures seen after cerebellar injections into lobules V and VI were comparable to those previously reported and permitted evaluation of the relay from dorsal root ganglia through the intercalatus to the vermis. Topography of the cervical projections to the nucleus intercalatus is considered with respect to that of the perihypoglossal-collicular projection. A discussion is offered of the apparent importance of nucleus intercalatus as a relay of cervical and vestibular afferent information to premotor structures involved in neck motor control. The perihypoglossal complex is viewed as being organized in such a fashion as to allow the nuclei intercalatus and prepositus hypoglossi to function as key structures in the integration of inputs related to neck and ocular motor control, respectively.

A transcervical surgical approach to the ventral medulla of the cat.

For the purpose of injection of anatomical tracers, it is desirable to have a surgical approach which provides the most direct approach to the target structure. This minimizes the amount of neural tissue that must be transgressed, and hence the leakage of tracer along the tract and the potential undesirable labelling that may result from this. In addition, visual guidance is preferable to stereotaxic guidance of injections where possible, particularly in situations where the target structure is far removed from the ear bar zero coordinate. Some of our work has necessitated small, discrete injections in the inferior olive sparing the adjacent reticular formation. The ventral transcervical approach to the medulla which was developed for this purpose is described below. It may conceivably be of use to physiologists wishing to record from ventral medullary structures. We feel it is a useful technique, but one which those with little surgical experience might not attempt. It is hoped that our description may guide others who could benefit by this approach.

The trigeminal evoked potential: Part II. Intraoperative recording of short-latency responses.

Short-latency (< 10 msec) trigeminal evoked potentials were studied intraoperatively in 31 patients under general anesthesia. Stimulation was performed peripherally in the face as well as centrally at the trigeminal nerve root entry zone. Recordings were made directly from the trigeminal root entry zone and far field from the scalp. Two principal negative deflections were noted, N1.6 and N2.6; and two waves that were less constantly identified were N.9 and N4-6. The latencies of these responses necessitated an extra-axial origin. It was concluded that this technique provided the ability to monitor the integrity of the extra-axial trigeminal nerve, but not the central trigeminal circuitry.

The trigeminal evoked potential: Part I. Long-latency responses in awake or anesthetized subjects.

Trigeminal evoked potentials have been elicited with differing methodologies that render responses almost as numerous as the number of laboratories reporting them. Forty-six trigeminal nerves were studied to investigate trigeminal evoked potentials in 20 awake, normal subjects and 20 patients undergoing surgery with general anesthesia. A comparison was made between different methods of surface stimulation and subdermal stimulation. It was concluded that these techniques had no practical use in intraoperative monitoring.

Repair of temporosphenoidal encephalocele with a vascularized split calvarial cranioplasty: technical case report.

A 54-year-old woman was referred for the evaluation and treatment of spontaneous cerebrospinal fluid rhinorrhea. Magnetic resonance imaging revealed a right anteromedial intrasphenoidal encephalocele with cisternography showing the flow of contrast into the sphenoid encephalocele. Transcranial surgical repair was performed. This included the use of a vascularized split-thickness calvarial graft fixated over the cranial base defect with a titanium microplate. The technical details of this repair are discussed. Ten cases of temporosphenoidal encephaloceles have been reported. The literature concerning this rare form of encephalocele is reviewed.

Percutaneous transfacial needle biopsy of a middle cranial fossa mass: case report and technical note.

A case of a patient with a middle fossa mass that was considered to be either a metastatic lesion or a benign intracranial neoplasm is presented. The definitive management of the patient depended on a tissue diagnosis. A biopsy was obtained using a transfacial needle aspiration technique through the foramen ovale. The details of this procedure are described.

Intraoperative mapping of the trigeminal nerve root: technique and application in the surgical management of facial pain.

A method for intraoperative topographic mapping of the trigeminal nerve root using electrophysiological methods is described. A series of 15 patients under general anesthesia during microvascular decompression and selective posterior fossa trigeminal rhizotomy was studied. This method was used to study the localization of fibers of individual subdivisions of the intradural portion of the trigeminal nerve and as a guide for performing physiologically controlled, selective, microsurgical trigeminal rhizotomy.

Rapid polymerizing fibrin glue from autologous or single-donor blood: preparation and indications.

A recipe for the preparation of a rapid polymerizing fibrin glue from single-donor or autologous blood products is presented. An in vitro investigation of different recipes with study of polymerization times, consistency, and in vitro survival of the product is described. The preparation in the operating room and the indications for clinical use of this glue in neurosurgery are discussed. The results of its use in a series of 38 patients is presented, including those undergoing surgery of the skull base, pituitary gland, cranial nerves, and the spine.

Cervical myelopathy in diffuse idiopathic skeletal hyperostosis. Case report.

The case of a rapidly progressive cervical myelopathy in a 64-year-old man is presented. Radiological studies revealed a partial extradural block, which at surgery was found to be a focal fibrous, calcified mass associated with the ligamentum flavum. On the basis of the underlying disorder of diffuse idiopathic skeletal hyperostosis (DISH), the etiology of this compression was concluded to be focal fibrous proliferation and dystrophic calcification. The neurological complications of DISH are reviewed. The authors are not aware of any other reports of this cause of myelopathy associated with DISH.

Spinal meningioma en plaque. Report of two cases.

Two cases of spinal meningiomas exhibiting en plaque patterns of growth are presented, one of which is reviewed more fully with emphasis on the radiographic and histological characteristics. The difficulties in diagnosis of this unusual tumor, its surgical management, and its postoperative course are discussed.

Meningioma in congenital adrenal hyperplasia.

A diversity of malignancies have been reported in patients with congenital adrenal hyperplasia. We report a case of multiple meningiomas, tumors which are more common in females and reported to have sex steroid receptors, in a 46,XX male (severe female hermaphrodite raised as a male) with 21-hydroxylase deficiency. The patient has been treated with glucocorticoids since 3 years of age and testosterone since puberty.

Technical strategies and anatomic considerations for parapedicular access to thoracic and lumbar vertebral bodies.

OBJECTIVES: To investigate and illustrate a variation on the traditional percutaneous access to the vertebral body via a parapedicular approach. DESIGN: An effective parapedicular access technique that could safely and reliably guide the needle tip into the center of the vertebral body was developed from cadaver dissection observations for the purpose of clinical use. PATIENTS: A total of 102 vertebral compression fractures from T-4 to L-5 were treated via the parapedicular access at our institution between July 2005 and March 2006. There were 72 patients between the ages of 17 and 96 years (mean age: 68.2 years) who underwent treatment. RESULTS: The cadaver dissection revealed a relatively avascular and aneural portion of the vertebral body along the superior margin of the vertebral body-pedicle junction. A total 102 vertebral fractures were treated using the parapedicular access technique without any recognized clinical complications from the needle access or the instrumentation. CONCLUSIONS: The thoracic and lumbar vertebral bodies may be safely, reliably, and reproducibly accessed using a percutaneous parapedicular access technique. The technique presented represents a relatively avascular and aneural approach to vertebral body.

Neurophysiologic monitoring during cranial base surgery.

The last decade has seen a rapid growth in surgical techniques directed at resection of skull base tumors. Lesions that were previously inoperable can now be resected either partially or in some cases completely. The morbidity in these procedures has diminished with increased surgical experience. Additional aids to successful surgical resection include intraoperative neurophysiologic monitoring techniques. The following text outlines methods of monitoring cranial nerve and brain function in a manner that is directly relevant to cranial base surgery in which so many structures are potentially at risk. These techniques permit the identification of nerves obscured by tumor before they may be inadvertently damaged, the repeated confirmation during tumor resection that a nerve is still functional, and infer the state of brain and brainstem function during the course of long surgical procedures to help signal vascular compromise, or the effects of brain retraction. These techniques can only help to enhance the safety of the long and complex procedures required for successful resection of tumors of the cranial base.