Anatomical relationships between Sylvian fissure and the sphenoid ridge.

During pterional craniotomy, the sphenoid ridge is resected to facilitate the dissection of the arachnoid in the Sylvian fissure. It is a common intra-operative perception that a deep sphenoid ridge often accompanies a shallow fissure. We explored this unique relationship between the sphenoid ridge and the Sylvian fissure. We studied 46 fresh adult cadavers and measured the depth of both the sphenoid ridges and the Sylvian fissure. The deepest portion of the sphenoid ridge was determined and its depth measured by using a narrow ruler with a sliding gauge. The depth of the Sylvian fissure was measured from the middle cerebral artery bifurcation perpendicularly to the surface of the temporal pole where the arachnoid was cut. An inverse relationship exists between the Sylvian fissure and the sphenoid ridge. The depth of the sphenoid ridge averages 7.28 mm +/- 0.3 mm while the depth of the Sylvian fissure averages 9.0 mm +/- 0.4 mm. Approximately 25% of studied population have deep ridges, i.e. greater than 10 mm, and approximately 25% have shallow ridges, i.e. less than 4 mm. The extent to which the sphenoid ridge projects into the Sylvian fissure determines the depth of the Sylvian fissure thus explaining their inverse relationship. Importantly, encountering a shallow sphenoid ridge during surgery most likely will result in the dissection of a deep Sylvian fissure while a deep ridge predicts a shallow fissure.

Hematogenous pyogenic facet joint infection of the subaxial cervical spine. A report of two cases and review of the literature.

Two cases of hematogenous, pyogenic, subaxial cervical facet joint infection are reported, and the literature is reviewed. Infection of the cervical facet joint is a rarely diagnosed condition; only one case has been reported in the literature. Lumbar facet joint infections are also rare but more commonly reported. Approximately one fourth of facet joint infections in the lumbar spine are complicated by epidural abscess formation, which can lead to a neurological deficit. Because of the paucity of reports on cervical facet joint infections, the clinical characteristics of this entity are not well known. Both patients presented with an acute onset of unilateral neck pain that radiated into the ipsilateral shoulder. Frank radicular pain was initially absent. Unilateral upper-extremity motor weakness that was attributed to associated epidural abscess or granulation tissue formation was also demonstrated in both patients. Leukocyte count and erythrocyte sedimentation rate were elevated in both cases. Magnetic resonance imaging was necessary to obtain an accurate diagnosis. Staphylococcus aureus was identified as the offending pathogen in both cases. Decompressive surgery and antibiotic therapy were required to cure the condition. One patient recovered completely and the other sustained a permanent motor deficit. Hematogenous cervical facet joint infection is a rare clinical entity that has many characteristics in common with the more-common lumbar homolog. All three reported cases, however, have been complicated by epidural abscess or granulation tissue formation that has led to a neurological deficit. This finding suggests that a facet joint infection in the cervical spine may have a less benign clinical course than that in the lumbar spine.

Techniques and pitfalls of cervical lateral mass plate fixation.

We studied 35 successive patients who underwent subaxial lateral mass fixation between June 1994 and January 1996. Follow-up ranged from 2 to 3 1/2 years. Postoperative computed tomography scans showed 45 of 146 screws (31%) had suboptimal trajectory, but only 2 screws minimally impinged the foramen transversarium without adverse sequelae. The fusion rate was 89%. Study results show that optimal drilling technique and trajectory (15 degrees-25 degrees rostral in the sagittal plane, 20 degrees-30 degrees lateral in the axial plane) and intraoperative somatosensory evoked potential monitoring are associated with good screw placement and avoidance of complications, and bone grafting is associated with higher fusion rates.

Oncocytoma in melanocytoma of the spinal cord: case report.

OBJECTIVE AND IMPORTANCE: Oncocytoma in the central nervous system is extremely unusual. The first reported example of oncocytoma in a melanocytoma of the spinal cord was successfully excised, and its pathological appearance is described. CLINICAL PRESENTATION: A 71-year-old woman presented with a 25-year history of back pain and myelographic evidence of a lumbar spinal cord mass. After declining surgical treatment for two decades, she elected eventually to have the mass excised. Preoperative magnetic resonance imaging revealed a large intraspinal mass that spanned spinal levels L3 through S1. TECHNIQUE: The mass was excised en bloc through posterior laminectomies, and histopathological analysis revealed a benign neoplasm composed predominantly of monotonous sheets of plump oncocytes. Electron microscopy confirmed that the cytoplasm of the oncocytes was packed full of mitochondria. Focal areas of the tumor contained spindle cells, with abundant intracytoplasmic granular deposits of brown melanin pigment that contained melanosomes. Positive Fontana-Masson, HMB-45, and S-100 staining confirmed the final diagnosis of melanocytoma, oncocytic variant. CONCLUSION: The first reported case of oncocytoma arising in spinal melanocytoma is described. After surgical excision, the patient recovered completely and has remained free of symptoms for 4 years.

Punctate midline myelotomy for the relief of visceral cancer pain.

OBJECT: This study offers clinical support for the concept that neurosurgical interruption of a midline posterior column pathway by performing a punctate midline myelotomy (PMM) provides significant pain relief without causing adverse neurological sequelae in cancer patients with visceral pain refractory to other therapies. METHODS: A PMM of the posterior columns was performed in six cancer patients in whom visceral pain had been refractory to other therapies. The cause of the visceral pain was related to residual, progressive, or recurrent local cancer or postirradiation effects. Clinical efficacy of the procedure was examined by comparing patient pain ratings and narcotic usage pre- and post-PMM. Follow-up periods ranged from 3 to 31 months. Examination of the results indicates a significant reduction in pain ratings as well as a significant reduction in daily narcotic use. No adverse neurological effects were observed. One spinal cord has been recovered for postmortem examination. CONCLUSIONS: These findings provide corroborating clinical evidence for the existence of a newly recognized midline posterior column pathway that mediates the perception of visceral pelvic and abdominal pain. Preliminary data indicate that significant pain relief can be obtained following PMM with minimal neurological morbidity and suggest that the procedure may provide an alternative treatment modality for cancer-related pain in patients in whom adequate pain control with narcotics cannot be achieved or narcotic side effects cannot be tolerated.

Intraventricular infusion of nerve growth factor as the cause of sympathetic fiber sprouting in sensory ganglia.

OBJECT: The results of previous clinical trials have indicated that intraventricular infusion of nerve growth factor (NGF) in patients with Alzheimer's disease is frustrated by the appearance of weight loss and diffuse back pain. The present study tested whether NGF induces sympathetic sprouting in sensory ganglia. Such sprouting has been implicated in previous studies as a possible mechanism of sympathetically maintained pain in neuropathic animals. METHODS: Nineteen Long-Evans rats underwent intraventricular infusion of either artificial cerebrospinal fluid (ACSF; seven animals) or NGF (12 animals). After 14 days of infusion, the sensory ganglia of the trigeminal nerve and the C-2, C-8, T-1, L-4, and L-5 dorsal roots were examined for sympathetic sprouting by using tyrosine hydroxylase immunohistochemical analysis. CONCLUSIONS: In the animals receiving NGF, 52 of 144 ganglia showed sympathetic fiber sprouting. In the control animals receiving ACSF, only two of 72 ganglia showed minor sympathetic fiber sprouting. A preferential sprouting of sympathetic fibers was demonstrated at lower lumbar ganglia compared with the cervical and thoracic ganglia. The data presented here demonstrate that in the rat intraventricular NGF infusion caused sympathetic sprouting in dorsal root ganglia (p < 0.01). These findings may have importance both for the treatment of Alzheimer's disease and the understanding of neuropathic pain.

Blastomycosis of the lumbar spine: case report and review of the literature, with emphasis on diagnostic laboratory tools and management.

We report on the conservative and surgical management of a patient with blastomycosis of the lumbar spine, causing severe and crippling deformity. The diagnosis was made through biopsy. Curative removal, reconstruction and realignment of the spine were achieved. Imaging modalities were highlighted, with a detailed discussion of the histology and conservative and surgical management. We emphasize the importance of early, aggressive treatment of blastomycosis to prevent deformity and disability, and to enable identification of the best management of a destructive lesion with deformity. This case demonstrates that empirical treatment should not be used in cases of unusual sinus and abscess locations. Specific diagnosis and early treatment are indicated to prevent dreadful complications and spinal deformity resulting from blastomycosis. Aggressive antifungal therapy can cure the disease but does not control complications related to deformity. The latter can only be addressed by surgical reconstruction. We review the literature of surgical treatment, focusing on abscess drainage, bone fusion and posterior instrumentation in the absence of addressing the deformity component.

Recurrent facial neuromas.

OBJECTIVE: The study aimed to present clinical, radiographic, and operative findings in cases of recurrent facial neuromas and discuss changes in demographics of primary facial neuromas since 1986. DATA SOURCES: MEDLINE search of English language literature since 1966 and bibliographies of collected articles were the data sources. STUDY SELECTION: All available reports of recurrent facial neuromas (N = 8) and case reports of primary facial neuromas since 1986 (N = 238) were selected. DATA EXTRACTION: Cases of facial neuromas confirmed by histologic and/or clinical and radiographic criteria are included. DATA SYNTHESIS: Compilation of reported anatomic and clinical data is included. CONCLUSIONS: Improved imaging techniques have documented an increased incidence of primary facial neuromas medial to the geniculate ganglion. Clinical suspicion, histologic confirmation of tumor-free margins, interspecialty cooperation in tumor resection, and routine follow-up imaging with magnetic resonance imaging are suggested to minimize recurrent facial neuromas.

Neuro-ophthalmologic manifestations of adenoid cystic carcinoma.

Intracranial adenoid cystic carcinoma is uncommon. We report two unusual cases of intracranial adenoid cystic carcinoma. The first patient presented with a steroid-responsive optic neuropathy from an orbital mass that simulated orbital pseudotumor, and subsequently developed intracranial involvement, presumably by contiguous perineural spread. The second patient presented with proptosis of the left eye, right facial weakness and numbness, and an intracranial mass, presumably from hematogenous metastatic spread.

Cognitive sequelae of unilateral posteroventral pallidotomy.

OBJECTIVE: To examine the cognitive sequelae of unilateral posteroventral pallidotomy. DESIGN: Single-group pretest and posttest methodologic assessment with baseline evaluation performed 1 to 2 days prior to surgery and follow-up conducted 3 months after pallidotomy. SETTING: Movement disorder clinic at a university medical center. PATIENTS: Fourteen patients (age range, 43-82 years) with Parkinson disease (average disease duration, 7.4 years). INTERVENTION: Unilateral posteroventral pallidotomy procedures were performed on the right (n=8) and left (n=6) side of the brain. MAIN OUTCOME MEASURES: The protocol consisted of a range of neuropsychological instruments sensitive to subcortical dysfunction, including measures of bi-manual coordination, simple-complex reaction time, visual attention, naming, verbal fluency, learning, recognition memory, and problem solving. RESULTS: No significant deterioration in specific cognitive abilities was observed as a function of the procedure. Patients showed a significant improvement in motor coordination speed for both contralateral and ipsilateral upper extremities. CONCLUSIONS: Stereotactic unilateral posteroventral pallidotomy is associated with minimal risk of adverse neuropsychological effects or cognitive decline. Additional research is warranted, with an increased sample size and extended follow-up, to assess any potential lateralized effects of the procedure.

Surgical interruption of a midline dorsal column visceral pain pathway. Case report and review of the literature.

A punctate midline myelotomy performed in a patient effectively eliminated residual, intractable pelvic pain, which remained after resolution of uterine cervical cancer. The authors describe the case history of the patient, in whom pain assessments were made, and a surgical procedure performed. Despite large doses of opiate analgesic medications, the patient experienced constant pressure pain in the right lower pelvis, with excruciating pain on bowel movement. Severe weight loss necessitated better pain control. A minimally invasive surgical procedure, a 5-mm deep puncture using a 16-gauge needle on either side of the median septum in the dorsal column of the spinal cord (T-8), resulted in no new neurological deficits. Narcotic medication was tapered, no pain was reported, and the patient resumed daily household activity. Midline myelotomy has typically been performed with the intention of eliminating the crossing fibers of the spinothalamic tract in the anterior white matter commissure. The punctate midline myelotomy described here was performed with the specific intention of interrupting a newly described visceral pain pathway that ascends to higher brain centers through the midline of the dorsal column. The effectiveness of the pain relief seen in this patient suggests that visceral pain of the pelvis in humans may be transmitted in the midline of the dorsal column, as has been recently reported in studies using rats. The effectiveness of the punctate midline myelotomy performed in this one case of pelvic visceral pain suggests that the surgery may eventually be effective in greatly reducing or replacing opiate narcotic medication for visceral pain management.

The value of intraoperative ultrasonography in cervical corpectomy: assessment by postoperative computed tomography.

OBJECTIVE: We assessed the value of intraoperative ultrasonography (IUS) in cervical corpectomy by using postoperative computed tomography (CT) for comparison. METHODS: Twenty patients underwent a one-, two-, or three-level cervical corpectomy. The decompression was performed in a stepwise fashion, guided in each case by IUS findings until considered adequate. Each patient underwent postoperative CT to evaluate the accuracy of the IUS in guiding the decompression. RESULTS: In the 20 patients who underwent corpectomy, IUS guided a complete lateral gutter decompression. No evidence of asymmetry and excessive bone removal was identified by IUS at the end of the procedure. IUS was not useful in assessing the adequacy of longitudinal decompression because of the absence of neural landmarks in the sagittal plane. Postoperative CT confirmed adequate decompression in all patients. The width of decompression at the posterior margin of the vertebral body ranged from 18 to 20 mm, with a mean of 19.2 mm. CONCLUSION: We conclude that IUS is helpful and reliable in performing a properly centered, thorough, lateral decompression in cervical corpectomy. A limited corpectomy can be started under visual guidance and then enlarged after IUS findings until complete decompression of the neural elements has been achieved. This approach avoids the problems of asymmetry, inadequate decompression, and excessive bony removal that could lead to endangerment of the vertebral artery and possible failure of the reconstruction. The accuracy of the IUS was confirmed in this study by postoperative CT.

Percutaneous transpedicular management of discitis.

PURPOSE: To present the technique of percutaneous transpedicular biopsy and debridement of discs in diagnosis and management of discitis. MATERIALS AND METHODS: Fifteen patients underwent disc biopsy through a transpedicular approach with local anesthesia and fluoroscopic guidance. An attempt was made to debride the disc as much as possible. A surgical vacuum drain was deployed through the transpedicular tract when there was persistent drainage. RESULTS: Fifteen patients underwent percutaneous transpedicular disc biopsy and debridement of disc for suspected discitis. Three patients underwent biopsy only and 12 underwent percutaneous discectomy. Six patients had at least one positive culture. Eight patients who underwent discectomy had immediate improvement of pain or neurologic symptoms, obviating emergency surgical debridement of the disc. Four patients did not improve and underwent surgical debridement and fusion. CONCLUSIONS: Transpedicular biopsy of the disc is an effective technique for adequate tissue retrieval and diagnosis of discitis. Adequate debridement in selected patients with antibiotic therapy may be definitive. Epidural extension of discitis and massive vertebral destruction precludes percutaneous treatment.

Treatment of carotid-cavernous sinus fistulas using a superior ophthalmic vein approach.

The authors describe the method and results of treatment of 12 consecutive patients with carotid-cavernous sinus fistulas (CCFs). Treatment was by embolization via a transvenous approach through the superior ophthalmic vein (SOV). The CCFs (two direct and 10 dural) had previously been treated unsuccessfully or, for mechanical reasons, could not be treated by the standard techniques of endoarterial balloon occlusion, particle or glue embolization of feeding vessels from one or both external carotid arteries, or transvenous occlusion of the fistula via the ipsilateral inferior petrosal sinus. All 12 patients were successfully treated either by advancement of a detachable balloon catheter through the ipsilateral SOV into the cavernous sinus with subsequent inflation and detachment of the balloon (11 patients) or by introduction of multiple thrombogenic coils into the fistula via the ipsilateral SOV (one patient). All patients had complete resolution of symptoms and signs after successful occlusion of the CCF. There were no intraoperative complications; however, one patient required postoperative embolization of a residual posteriorly draining fistula via the ipsilateral external carotid artery, and another developed a persistent abducens nerve paresis that eventually required surgical correction. Ten (83.3%) of the 12 patients underwent cerebral angiography 3 to 6 months after surgery, and none showed evidence of a recurrent fistula. Similarly, none of the 12 patients developed recurrent symptoms and signs suggesting recurrence of the fistula during a follow-up period that ranged from 6 months to 10 years (mean 64 months). It is concluded that the transvenous approach to the cavernous sinus through the SOV is a safe and effective treatment of both direct and dural CCFs that are not amenable to transarterial or other transvenous approaches.

Validation of transcranial Doppler ultrasound with a stereotactic neurosurgical technique.

Vessel identification during a transcranial Doppler (TCD) ultrasound examination is usually based on well-established inferential criteria without confirmation by imaging. Part of a routine study involves taking measurements from the M1 segment of the middle cerebral artery (MCA) and the A1 segment of the anterior cerebral artery (ACA) at the points of maximum mean linear blood flow velocity (LBFV). The authors tested the hypothesis that insonation is from the midpoints of the M1 and A1 segments during clinical TCD examinations. Conventional hand-held TCD examinations were performed on five volunteers. The points of maximum mean LBFV of the M1 and A1 segments of the MCA and ACA were located. Measurements were also taken from the midpoints of the M1 and A1 segments using a magnetic resonance (MR) imaging-guided stereotactic TCD technique. Values for depths of insonation and maximum mean LBFV obtained with the two techniques were compared. There was no significant difference between the two techniques for the measured values of depth of insonation of either the individual vessels (p > 0.11) or the aggregate (p = 0.46). There was a significant difference between the aggregate maximum mean LBFV measurements (p = 0.0022). The hand-held technique systematically produced higher maximum mean LBFV than the MR-guided stereotactic technique. The authors conclude that when using traditional criteria for TCD examination of the ACA and MCA, the points of insonation approximate the middle of the A1 and M1 segments.

Giant serpentine aneurysms: a review and presentation of five cases.

We present five cases of giant serpentine aneurysms (large, partially thrombosed aneurysms containing tortuous vascular channels with a separate entrance and outflow pathway) and review 28 cases reported in the literature. Giant serpentine aneurysms should be considered as a subgroup of giant aneurysms, distinct from saccular and fusiform varieties, given their unique clinical presentation and radiographic features.

Error assessment during "image guided" and "imaging interactive" stereotactic surgery.

The mechanical accuracy of several available stereotactic instruments is extremely high as measured in tests with rigid phantoms. The author's experience with stereotactic-guided resection by craniotomy using both "frameless" and framed methods simultaneously is that neither the image accuracy nor the mechanical accuracy of the instrument is the limiting factor in the usefulness of the guidance. Rather, it appears that the errors encountered in actual use have to do with tissue position changes which occur during the procedure. The accuracy may be better for extrinsic lesions rigidly attached to the skull, but for intrinsic lesions, tissue position changes occur following the release of cerebrospinal fluid, air entry into the subdural spaces, tumor debulking, or cyst drainage. The potential error appears to be worse with hydrocephalus, intraoperative dehydration, collapse of larger cysts, and debulking of large tumors. Even with very small intrinsic tumors in young, not atrophic patients, the error may be 5 mm. The need for intraoperative update of the guidance image is obvious if greater accuracy is required. The advantages of such "imaging-interactive" stereotactic surgery have long been apparent from stereotactic biopsy procedures performed in the CT scanner where errors such as needle deflection or hemorrhage can be appreciated and corrected promptly. With intraoperative scanning it is also possible to monitor the progress of a cyst aspiration and confirm the site of a biopsy to avoid unnecessary sampling in cases where the pathology is inherently equivocal.

Intra-arterial urokinase for treatment of retrograde thrombosis following resection of an arteriovenous malformation. Case report.

Retrograde thrombosis of feeding arteries is a potentially catastrophic complication occasionally reported following resection of arteriovenous malformations (AVM's). No successful therapy for this condition, which causes postoperative stroke, has previously been reported. A case of retrograde thrombosis of the left middle cerebral artery immediately following resection of a parietal AVM is reported in a patient with a retained intra-arterial catheter from preoperative embolization. The administration of urokinase within 4 hours of surgery resulted in dramatic clinical and angiographic improvement without hemorrhagic complications. While urokinase is considered highly experimental in this setting, this case demonstrates that thrombolytic agents should be viewed as therapeutic options worthy of further investigation.