Delayed cervical spinal cord tethering following tonsillar resection for Chiari malformation.

Although tethering of the spinal cord in the lumbosacral region, particularly following repair of congenital anomalies, such as myelomeningocele, is a well-known phenomenon, only sporadic reports of tethering along the rest of the neuraxis, including the hindbrain, cervical and thoracic spinal cord have been documented. In this report, we describe a woman who developed symptoms related to tethering of the cervical spinal cord 5 years after suboccipital decompressive surgery of the posterior fossa for Chiari I malformation. The authors discuss the diagnosis, treatment, and postoperative course of this entity.

Epidemiology of ventriculostomy in the United States from 1997 to 2001.

Ventriculostomy is a common practice in neurosurgery, but the annual trend of this procedure in the United States has not been reported in the literature. This study evaluates the annual trend during a recent 5-year period. Between 1997 and 2001, a retrospective review was undertaken concerning all patients in the Nationwide Inpatient Sample (NIS) who had undergone ventriculostomy. The population sample represented approximately a 20% stratified sample of nonfederal hospitals in the United States. The annual number of patients who underwent ventriculostomy during the study period ranged from 20,586 to 25,634. Most patients were male (53.4%), with a mean age of 44.8 years, were commercially insured (46.0%) and had a median annual income above $25,000 (84.4%). Most frequent ICD-9-CM diagnoses were subarachnoid haemorrhage, intracerebral haemorrhage and obstructive hydrocephalus, respectively. The majority of ventriculostomies were performed in large, private, not-for-profit, metropolitan, teaching institutions. Mean length of hospital stay was 19.2 days. Regarding discharge status for patients who had undergone ventriculostomy, approximately one-quarter died in the hospital, one-third were discharged home and one-third were transferred to another institution. No demographic variables changed during the study with the exception of location of ventriculostomy in a teaching hospital, which increased from 64.4% in 1997 to 77.4% in 2001. Patient and hospital demographic characteristics were consistent during the study period. By extrapolation of the data, the prevalence of ventriculostomy in the United States averaged 24,380 per year. This study is the first to comprehensively document data concerning the epidemiology of this common procedure.

Exclusion of cervical spine instability in patients with blunt trauma with normal multidetector CT (MDCT) and radiography.

The objective of the study was to determine if negative multidetector computed tomography (MDCT) and lateral radiography of the cervical spine effectively excludes patients with unstable cervical spine injuries. Over a period of 40 months, 6558 people were admitted to our trauma service with blunt injury and 447 (6.8%) were found to have cervical fractures. Fractures were identified by CT and/or lateral radiography. In order to rule out clinically significant instability in the absence of fracture, we identified nine patients who required any type of stabilization of the cervical spine including anterior fusion, posterior fusion and external orthosis. These patients also underwent MR of the cervical spine. Radiography, CT, and MR images and reports of these nine patients were reviewed. Nine patients without a fracture required cervical stabilization. These patients had the following abnormalities: disc herniation with canal stenosis in three, unilateral jumped facet in three, and various other soft tissue abnormalities in three, all of which were evident on CT or radiography. All nine patients had evidence for cervical spine injury or instability by MDCT. Normal MDCT and radiography appears adequate to 'clear' the cervical spine. We recommend that patients requiring cervical spine clearance undergo a complete MDCT and lateral radiograph of the cervical spine. If these studies are entirely normal, then the cervical spine may be cleared. If any abnormalities, including disc herniation, soft tissue swelling and bony malalignments are noted by radiography and/or MDCT, further studies, including MR, are indicated prior to clearance of the cervical spine.

Palatal myoclonus. Reflex activation of contractions.

We report two unusual features of a 37-year-old man with palatal myoclonus. Although the rhythmic palatal contractions of this disorder are usually incessant, he was able to voluntarily suppress them for minutes. During periods of suppression, specific voluntary actions using the left side of his body, but not the right, reliably elicited single contractions. Various stimuli to the left side of his body, but not the right, also produced single contractions. Stimulation of trigeminal nerve branches evoked palatal electromyographic discharge after 55 ms. Microsurgical vascular decompression of posterior fossa neural structures led to improvement of several of the patient's symptoms and signs.

Hemifacial spasm: results of electrophysiologic recording during microvascular decompression operations.

Electrophysiologic recordings were made from patients with hemifacial spasm (HFS) during microvascular decompression (MVD) operations to see if spasm and synkinesis are caused by ephaptic transmission at the site of lesion (root entry zone [REZ] of the facial nerve). The response from the orbicularis oculi muscle to electrical stimulation of the marginal mandibular nerve had a 2.2-msec longer latency (average of 16 patients) than the sum of the conduction times of the parts of the facial nerve that would be involved if the response was the result of ephaptic transmission at the REZ of the seventh cranial nerve. Similar results were obtained when the zygomatic branch of the facial nerve was stimulated. These results indicate that the facial motonucleus is involved in HFS.

Pathophysiology of hemifacial spasm: III. Effects of facial nerve decompression.

We studied 59 patients with hemifacial spasm before decompression of the facial nerve in the cerebellopontine angle. Fifty-three patients were reexamined 1 week later, and 30 patients after 2 to 8 months. Within 1 week, ephaptic transmission disappeared in 23% and changed from bidirectional to unidirectional in 45%. After-discharges disappeared in 64% and were mild in 34%. Synkinesis after supraorbital nerve stimulation disappeared in 53%, and the blink reflex amplitude became normal. After 2 to 8 months, ephaptic transmission was abolished in 73% and unidirectional in 17%. After-discharges and synkinesis disappeared in 90%, and the latency of the blink reflex decreased. It is concluded that decompression stops ectopic/ ephaptic excitation due to decrease in the interstitial resistance, and enables remyelination.

Vascular compression, hemifacial spasm, and multiple cranial neuropathy.

Hemifacial spasm is usually an isolated symptom resulting from facial nerve root compression. Three patients had, in addition, tinnitus, hearing loss, facial sensory loss, diminished gag reflex, dysphagia, and dysarthria. Acoustic reflexes were abnormal, and facial nerve conduction studies showed evidence of ephaptic transmission and ectopic excitation. Brain CT and metrizamide cisternography were normal. Surgical exploration showed compression of cranial nerve roots by posterior inferior cerebellar artery branches. After decompression, symptoms abated, and electrical signs of hemifacial spasm disappeared. Vascular compression of nerve roots in the cerebellopontine recess may cause multiple cranial neuropathy.

Transplantation of cultured human neuronal cells for patients with stroke.

Transplantation of cultured neuronal cells is safe in animal models and improves motor and cognitive deficits in rats with stroke. The authors studied the safety and feasibility of human neuronal cellular transplantation in patients with basal ganglia stroke and fixed motor deficits, including 12 patients (aged 44 to 75 years) with an infarct 6 months to 6 years previously (stable for at least 2 months). Serial evaluations (12 to 18 months) showed no adverse cell-related serologic or imaging-defined effects. The total European Stroke Scale score improved in six patients (3 to 10 points), with a mean improvement 2.9 points in all patients (p = 0. 046). Six of 11 PET scans at 6 months showed improved fluorodeoxyglucose uptake at the implant site. Neuronal transplantation is feasible in patients with motor infarction.

Selective total removal of a growth-hormone-secreting adenoma: evidence that acromegaly is a primary pituitary disease.

Acromegaly is caused by hypersecretion of growth hormone by the pituitary. There is some debate as to whether the primary etiology of the disease is abnormal hypothalamic stimulation of the pituitary or a primary pituitary tumor. This paper presents a case of acromegaly in which growth hormone dynamics in response to stimulation and suppression tests were abnormal. After transsphenoidal adenomectomy of a small tumor, growth hormone levels returned to normal and suppression and stimulation test results reverted to normal within 1 wk postoperatively and remained normal for 2 yr. The findings suggest that the acromegaly in this case was due to a primary pituitary dysfunction. Microsurgical removal of growth-hormone-secreting tumors provides a unique opportunity to study the etiology of acromegaly.

Blink reflex in patients with hemifacial spasm. Observations during microvascular decompression operations.

The blink reflex cannot normally be elicited during surgical anesthesia using inhalation anesthetics. However, in patients with hemifacial spasm (HFS) the early component of the reflex response (R1) can be elicited on the affected side but not on the unaffected side during such anesthesia. The electromyographic (EMG) response from the mentalis muscle to stimulation of the supraorbital nerve was recorded during microvascular decompression (MVD) of the facial nerve to relieve HFS and compared to the response from the same muscle to stimulation of the zygomatic branch of the facial nerve in four patients. During the operation before the facial nerve was decompressed, contractions in both the orbicularis oculi and the mentalis muscles could be elicited by stimulation of the supraorbital nerve (mean latencies 12.2 +/- 1.9 and 12.9 +/- 2.0 ms, respectively). When the facial nerve had been decompressed the blink reflex could no longer be elicited, and there was no response from the mentalis muscle to stimulation of the zygomatic branch of the facial nerve. Compound action potentials (CAP) recorded from the 7th cranial nerve in response to stimulation of the supraorbital nerve had latencies of 7.5 ms +/- 1.4 ms to the negative peak.

Hemifacial spasm caused by a venule: case report.

The syndrome of hemifacial spasm occurs as a consequence of compression, almost universally by blood vessels, of the root entry zone of the facial nerve. The vascular compression is usually obvious at operation, but may be subtle. The author describes a case in which a venule running in an anterior-posterior direction across the caudal aspect of the root entry zone of the facial nerve, which was thought to be causing the spasm, was coagulated and divided. A small, more distal arteriole, probably not contributory, was decompressed away from the nerve. After operation, the patient improved gradually, and she remains free of facial spasm or weakness. This is the most subtle vascular compression seen by the author and his colleagues in over 400 microvascular decompressions for hemifacial spasm.

Trigeminal neuropathy--new observations.

Five cases of trigeminal neuropathy of the idiopathic variety are reported; one patient had an associated unilateral hypoglossal neuropathy with fasciculations and wasting of the ipsilateral half of the tongue. No demonstrable cause was found with the usual laboratory and neuroradiological examinations. Four of the patients underwent retromastoid craniectomy, and the microsurgical observations of the cerebellopontine angle are noted. The superior cerebellar artery (three cases) or anterior inferior cerebellar artery (one case) was found to be stretching the trigeminal nerve in all four case. Microvascular decompression provided pain relief and sensory recovery or improvement in all patients operated upon. In one case, the hypoglossal nerve was also found to be distorted by an arterial loop of a medullary artery; decompression of the loop resulted in complete recovery of hypoglossal function on the affected side. In cases of persistent idiopathic trigeminal neuropathy with or without intractable pain, retromastoid craniectomy with microvascular decompression of the 5th nerve is a therapeutic alternative. (Neurosurgery, 7: 347-351, 1980).

Use of perioperative steroids with microvascular decompression operations.

Complications associated with the use of perioperative steroids in elective craniotomies were evaluated in a single-blind prospective study of 222 consecutive microvascular decompression operations. Patients were randomized into one of three groups: Group A received steroids preoperatively and for 4 days postoperatively, Group B received steroids pre- and postoperatively for 1 day, and Group C received no steroids. There were 17 complications in Group A; 12 of these were wound-related. There were significantly fewer complications in Groups B and C (P less than 0.01). Group B had 3 complications, Group C had 4, and there was only 1 wound-related complication in Group C. There were no deaths, deep wound infections, or life-threatening complications. Severe postoperative headaches, a symptom that steroids were intended to minimize, occurred in 38% of patients in Group A, 42% of patients in Group B, and 25% of patients in Group C. The use of perioperative steroids did not reduce the length of postoperative hospitalization. Duration of the operation had no significant effect on the incidence of postoperative complications or the length of postoperative hospitalization. We conclude that there is no indication for the routine perioperative use of steroids with microvascular decompression operations of the posterior fossa cranial nerves and that such use leads to a higher incidence of postoperative complications.

Microvascular decompression in hemifacial spasm: intraoperative electrophysiological observations.

Facial muscle responses in patients with hemifacial spasm undergoing microvascular decompression operations were recorded. Two peripheral branches of the facial nerve were stimulated and the electrical responses of muscles innervated by these branches were studied to see how the lateral spread of activity that is known to be present in these patients was affected by decompressing the facial nerve. In some of the patients the hemifacial spasm ceased when the dura mater was opened, in some it ceased when the arachnoid was opened, and in others the spasm persisted until the offending vessel was dissected away from the nerve. The lateral spread of activity elicited by antidromic stimulation of a branch of the facial nerve was less affected by opening of the dura mater or arachnoid: it usually persisted until the blood vessel that had been compressing the facial nerve was removed and reappeared when the vessel that had been compressing the facial nerve was allowed to slip back onto the nerve. This seems to indicate that microvascular decompression of the facial nerve is effective in alleviating hemifacial spasm because it removes the actual cause of the disorder rather than simply causing local injury to the nerve as a result of the procedure.

Hemifacial spasm in young people treated with microvascular decompression of the facial nerve.

Hemifacial spasm (HFS) in childhood is extremely rare. Two patients with HFS in childhood and eight adults who had the onset of HFS before the age of 20 were treated with microvascular decompression of the facial nerve at the nerve root entry zone. The two children were both girls and had typical HFS on the right side. Of the eight adults, five were men and three were women. Six had typical and two had atypical HFS. Six had HFS on the left side, and two had HFS on the right. Vascular cross compression was found at the nerve root entry zone in all cases. The average follow-up period was 7.3 years (range, 1 1/2 to 11 years). All but one patient had complete relief of their HFS immediately or after delay. In one adult, the compressing artery could not be decompressed without damaging the nerves. One adult patient had two recurrences 1 year after the first operation and 6 months after the second; this patient had complete relief after a third operation. Complications included temporary mild facial weakness in four patients and moderate hearing impairment in the patient who had three operations. These results are comparable to those of HFS of adult onset. Microvascular decompression is recommended as the treatment of choice for HFS during childhood.

Evoked potentials in trigeminal neuralgia.

Trigeminal evoked potentials and sensory thresholds in response to maxillary gum stimulation were obtained in patients with a complaint of unilateral face pain. The patients and the volunteer, normal control groups had undergone no prior surgical or other procedures involving cranial or cervical structures. For statistical purposes, patient data were analyzed with respect to the diagnostic classification of classical trigeminal neuralgia, atypical trigeminal neuralgia, or other face pain states in which the pain extended beyond the trigeminal nerve distribution. Latencies of trigeminal evoked potentials on the affected side were significantly increased (compared to normal control group responses) in patients with classical but not in those with atypical trigeminal neuralgia nor other face pain syndromes. All three patient groups had statistically significant threshold elevations on the affected side compared to the unaffected side. A high level of significance for this test was obtained for the classical trigeminal neuralgia group. Ratings for patients based upon the preoperative electrophysiological findings were highly correlated with long term results of microvascular decompression of the 5th nerve root for classical, but not for atypical trigeminal neuralgia patients. These results support the view that atypical and classical trigeminal neuralgia symptom complexes are caused by different types of physiological dysfunction and that classical trigeminal neuralgia is associated with compression of the trigeminal nerve root. It was suggested that the rating system may be a useful, objective, clinical adjunct in evaluating patients with classical trigeminal neuralgia.

Thoracic disc herniation: operative approaches and results.

In a series of 12 cases of thoracic disc herniation operated upon at the University of Pittsburgh, 4 different operative approaches were used. These included laminectomy in 2 early cases, posterolateral extrapleural operation in 5 cases, transthoracic operation in 3 cases, and transpedicular operation in 2 cases. The relative merits of the various approaches are discussed in this paper. The clinical presentation, radiological features, and follow-up data are also presented. Precise preoperative radiological diagnosis was essential in planning the operative strategy. The posterolateral and transpedicular approaches were both satisfactory, but the former had some advantages over the latter. With a mean follow-up period of 5 years, 5 patients were cured, 5 were improved, and 1 was unchanged. One patient was worse due to coexistent amyotrophic lateral sclerosis.

Neurinoma of the trigeminal root and atypical trigeminal neuralgia: their commonality.

Two cases of very small trigeminal neurinomas arising proximal to Meckel's cave are presented. We believe that the overlap of the symptoms and signs of these tumors with those of atypical trigeminal neuralgia strengthens the concept of the latter entity also being due to compression of the trigeminal nerve solely within the posterior fossa.

Recordings from human dorsal column nuclei using stimulation of the lower limb.

Responses from the surface of the dorsal column nuclei and the dorsal surface of the spinal cord were recorded using monopolar electrodes after stimulation of the lower limbs (common peroneal nerve at the knee and posterior tibial nerve at the ankle) in patients undergoing neurosurgical operations for spasmodic torticollis. Those responses were smaller in amplitude than responses to stimulation of the upper limbs (median nerve at the wrist), and the waveforms differed. The negative deflection that is prominent in the response to stimulation of the upper limbs is more variable, broader, and relatively smaller in amplitude than the response to upper limb stimulation. Another difference between responses to upper and lower limb stimulation was that multiple peaks were superimposed on the initial response to stimulation of the lower limbs, but were not as consistently seen in the responses to upper limb stimulation. The negative peak in the response from the dorsal column nuclei to lower limb stimulation was of about the same latency as the P27 peak in the far-field response (somatosensory evoked potential) to stimulation of the peroneal nerve.

Preservation of hearing in operations on acoustic tumors: an alternative to recording brain stem auditory evoked potentials.

The monitoring of auditory function by recording brain stem auditory evoked potentials in patients undergoing removal of acoustic tumors is hampered by the small amplitude of the brain stem auditory evoked potentials. Because several thousands of responses must be added, it takes several minutes to obtain an interpretable record. Recordings done directly from the exposed eighth nerve have much higher amplitudes, and, therefore, interpretable responses can be obtained after only a few responses have been added. However, it is difficult to place the recording electrode in an optimal position and the electrode may interfere with the removal of the tumor. In this report, we show that evoked potentials from the cochlear nucleus, which can be recorded by placing an electrode in the lateral recess of the fourth ventricle, have a large amplitude, and that the electrode placed in this way does not interfere with the removal of the tumor. This way of monitoring, therefore, yields interpretable responses within 15 to 20 seconds, or less, and makes it possible to detect injuries to the entire intracranial portion of the eighth nerve, just as brain stem auditory evoked potentials do, but 20 to 50 times faster.