Electrical bone graft stimulation for spinal fusion: a review

Although electrical stimulation to aid bone fusion is well established in the treatment of long-bone fractures, its use as an aid in spinal fusion is not as well documented. This article presents the history and scientific basis of electrical stimulation to aid bone fusion and extensively reviews the clinical literature. It is intended to provide an objective review of the indications and limitations of electrical stimulation to enhance spinal fusion and to serve as a reference source for further study.

Paraganglioma of the filum terminale: case report and literature review

A rare case of a paraganglioma of the filum terminale is reported. The patient presented with headache and papilledema. Magnetic resonance imaging demonstrated enlarged ventricles of the brain and a well-demarcated intradural spine tumor. After resection of the tumor, the papilledema and headaches resolved, and the ventricles returned to normal size. Pathologic examination revealed a paraganglioma of the filum terminale. We present this rare case and review the literature of spinal paragangliomas as well as the association of spinal tumors with hydrocephalus.

Transparaspinal exposure of dumbbell tumors of the spine. Report of two cases

The authors present a surgical technique for resection of dumbbell tumors of the spine. The transparaspinal exposure combines laminectomy and sectioning of the paraspinal muscles through a transverse incision. The procedure allows total tumor resection by means of a single posterior approach in selected patients, thus obviating the need for a combined anteroposterior operation. The advantages and disadvantages of the transparaspinal approach compared with the more extensive lateral extracavitary approach are discussed.

[Surgical approach to benign extradural lesions of the thoracic spine]

A benign epidural lesion in the thoracic spine is rare, and usually the result of intervertebral disc herniation or infection. Not long ago patients were diagnosed late in the course of their disease and the surgical results of the standard laminectomy usually performed were grave. The development of newer imaging techniques (CT and MRI) has made diagnosis much easier, so diagnosis is often earlier, when neurological deficit is minimal. Newer neurosurgical techniques and approaches to the thoracic spoine have been developed to treat these lesions, which we describe. Clinical data on 16 patients operated from January 1996 to January 1997 are presented.

Dorsal endodermal cyst of the upper cervical spine

This report describes a case of a rare, dorsally placed enterogenous cyst at the craniocervical junction. The patient had preoperative magnetic resonance imaging studies, followed by microsurgical removal of the cyst. The patient made an uneventful recovery from the surgery. Pathological examination revealed an enterogenous cyst. Although enterogenous cysts are more commonly found in the lower cervical or thoracic spine, it is important to recognize that they may also be found at the craniocervical junction. In addition, cysts may occur posterior to the chord. Microsurgical removal is usually effective in the treatment of these cysts.

False localizing signs in upper cervical spinal cord compression

Proprioceptive loss, paresthesias, and atrophy of the hands can occur with disorders afflicting the upper cervical spinal cord. The diagnosis might be erroneous, because compression in this region might produce signs and symptoms that seem to originate in the lower cervical cord. This article reviews the clinical presentation and radiographic data of a consecutive series of 11 patients who presented between 1992 and 1994 with an extradural lesion above the C4 level. Each patient had a characteristic syndrome of finger and hand dysesthesia, hand atrophy, and occipital or cervical pain. These complaints usually preceded the development of spasticity and gait disturbance. Initial diagnoses included brachial plexopathy, shoulder dysfunction, viral syndrome, and cervical spondylosis at a lower segment. Cervical spondylosis or a herniated disc was the most common pathogenesis. The most commonly involved level was C3-C4. Nine patients underwent a surgical procedure; eight showed significant postoperative improvement (mean time of follow-up examination, 9.7 mo; follow-up range, 1-24 mo). One patient was lost to follow-up. Although the pathophysiology of these findings is unknown, theories include anterior spinal artery ischemia, venous obstruction, and differential decussation of the forelimb and hindlimb fibers of the corticospinal tract. Recognition of this syndrome might prevent inappropriate operative intervention in patients with coexisting pathological conditions of the lower cervical spinal cord.

Biopsy-proven isolated sarcoid meningitis. Case report

Neurosarcoidosis without systemic involvement is rare and difficult to diagnose. The case of a 27-year-old man with a 6-week history of headache, mental status changes, and polyradiculopathy attributable to hypoglycorrheic lymphocytic meningitis is presented. Extensive testing for occult systemic sarcoidosis was negative. The presence of noncaseating granulomatous inflammation was established by open brain biopsy, and the patient improved clinically with oral steroid therapy. In individuals with undiagnosed chronic meningitis, brain biopsy may be necessary to rule out isolated neurosarcoidosis.

Wallenberg's lateral medullary syndrome. Clinical-magnetic resonance imaging correlations

OBJECTIVE

To correlate clinical and radiologic findings in patients with lateral medullary infarction.

DESIGN

Case series with "blinded" evaluation of brain imaging.

SETTING

Hospitalized and ambulatory patients at the Neurological Institute of New York (NY).

PATIENTS

Thirty-three consecutive patients with lateral medullary syndrome were evaluated by the Stroke Center between 1983 and 1989.

RESULTS

Ataxia (70%), numbness either of the ipsilateral face or of the contralateral body (64%), vertigo (51%), and dysphagia (51%) were the most frequent symptoms at onset. Eleven patients had ocular symptoms (diplopia or blurred vision). Horner's syndrome was found in 91%, ipsilateral ataxia in 85%, and contralateral hypalgesia in 85%. Nystagmus (61%) and facial weakness (42%) were less frequent. Head computed tomography was abnormal only when a cerebellar infarction was present (three cases). Magnetic resonance imaging, obtained in 22 cases, was normal in two; a lateral medullary infarction alone was present in 12, and a lesion extending beyond the lateral medulla was found in eight. No correlation was noted between facial weakness or ocular symptoms and infarction extending beyond the lateral medullary region. Vertebral artery disease was confirmed by vascular imaging or insonation studies in 73% of patients.

CONCLUSIONS

The triad of Horner's syndrome, ipsilateral ataxia, and contralateral hypalgesia will clinically identify patients with lateral medullary infarction. Facial weakness and ocular symptoms are frequent and do not necessarily imply that the infarction extends beyond the lateral medulla. Cerebellar infarcts only infrequently accompany lateral medullary syndrome, suggesting that most of the posterior inferior cerebellar artery territory is spared, despite the high frequency of vertebral artery occlusion.

Reduction by delayed hypothermia of cerebral infarction following middle cerebral artery occlusion in the rat: a time-course study

The effect of hypothermia on neuronal injury following permanent middle cerebral artery (MCA) occlusion in the rat was examined. Moderate hypothermia (body temperature 24 degrees C) was induced before MCA occlusion (0-minute delay group) in six rats, at 30 minutes in eight rats, and at 1 (seven rats), 2 (seven rats), and 3 (nine rats) hours after occlusion. The rats were kept at a 24 degrees C body temperature for 1 hour, then allowed to rewarm over 90 minutes. The animals were sacrificed 24 hours after MCA occlusion, and infarction was visualized by staining of coronal sections with 2,3,5-triphenyltetrazolium chloride. Infarct volumes were compared to matched normothermic control rats (body temperature 36 degrees C). Additional groups of 0-minute delay hypothermic (10 rats) and control animals (nine rats) were sacrificed 72 hours after MCA occlusion to examine the effects of prolonged survival. A significant reduction in the percentage of infarcted right hemisphere was seen in the animals sacrificed after 24 hours with 0-minute, 30-minute, and 1-hour delays in inducing hypothermia (mean +/- standard error of the mean: 2.2% +/- 0.7%, 4.4% +/- 0.9%, and 3.6% +/- 1.1%, respectively) as compared to normothermic control rats (10.8% +/- 1.5%, p less than 0.01 by Student's t-test). In the 2- and 3-hour delay groups, the percentage of infarcted right hemisphere was 17.1% +/- 2.4% and 12.0% +/- 2.7%, respectively, and no decrease in infarct volume was observed. The 0-minute delay hypothermia group sacrificed after 72 hours also displayed a significant reduction in right hemisphere infarct compared to their respective controls (4.8% vs. 11.7%, p less than 0.05). These findings indicate that, in the setting of permanent MCA occlusion, hypothermia markedly decreases brain injury even when its induction is delayed for up to 1 hour after the onset of ischemia. Ischemic damage does not appear to be merely retarded but permanently averted.

A simple and reliable technique to monitor intracranial pressure in the rat: technical note

A technique for intracranial pressure (ICP) monitoring in the rat that uses a permanent cisterna magna cannula is described. The cannula is placed into the subarachnoid space through the atlanto-occipital membrane with the operating microscope and is secured with cement. The distal end is connected to a pressure transducer and a polygraph recorder. To study the consistency of this technique, 12 anesthetized adult rats were subjected to baseline ICP measurements 2 days after placement of the cannula. Baseline pressures ranged between 1.0 and 10.0 cm H2O, with a mean of 5.6 cm H2O. Respiratory variations were detected in all tracings, and manual abdominal compressions (Valsalva maneuver) correlated with immediate transient rises in ICP in all rats. While CSF pressure was being continuously monitored, rats were subjected to subarachnoid hemorrhage induced by transclival basilar artery puncture. Of the 12 rats, 10 showed a moderate transient rise in cerebrospinal fluid pressure, which peaked approximately 2 minutes after subarachnoid hemorrhage (mean peak change, 10.5 cm H2O; range, 0-32.5 cm H2O). Reliable pressure tracings were obtained in three of five animals examined 3 days after subarachnoid hemorrhage (ICP range, 4.0-4.5 cm H2O; mean, 4.2 cm H2O). We conclude that this cannula is easy and inexpensive to construct and that it provides reliable ICP tracings during experimental procedures in the rat.

Transient hypothermia reduces focal ischemic brain injury in the rat

The effect of transient hypothermia on focal cerebral ischemia was evaluated using a rat model of permanent middle cerebral artery (MCA) occlusion. MCA occlusion was performed on 10 rats at a temporalis muscle temperature of 24 degrees C (hypothermic group) and on 10 rats at 36 degrees C (normothermic group). Rats in the hypothermic group were maintained at 24 degrees C for 1 hour after MCA occlusion and then allowed to rewarm to 36 degrees C over the next 2 hours. Animals in both groups were killed 24 hours after MCA occlusion. Cerebral infarcts were visualized by staining of coronal brain sections with 2,3,5-triphenyltetrazolium chloride. Normothermic rats displayed an average infarct volume of 233.1 +/- 13.2 mm3 (standard error of the mean), whereas hypothermic rats had an average infarct volume of 166.2 +/- 22.8 mm3 (P less than 0.01). Expressed as a percentage of the volume of the right hemisphere, the normothermic group had an infarct volume of 22.1 +/- 1.5% and the hypothermic group an infarct volume of 16.0 +/- 2.2% (P less than 0.05). These results demonstrate that transient hypothermia to a temporalis muscle temperature of 24 degrees C significantly reduces subsequent infarct size in an experimental model of permanent arterial occlusion.

Hypothermic protection following middle cerebral artery occlusion in the rat

The effects of deep hypothermia on ischemic neuronal injury were examined using a permanent middle cerebral artery occlusion model in the rat. Animals were maintained at temporalis temperatures of either 24 degrees C or 36 degrees C and killed 6 hours after arterial occlusion. Normothermic rats displayed an average infarct volume of 25.1% +/- 1.6% of the right hemisphere, whereas hypothermic rats had an average infarct volume of 4.1% +/- 1.3% (p less than 0.001). The right/left hemispheric ratio was 1.05 +/- 0.02 in the normothermic group and 1.00 +/- 0.02 in the hypothermic group (p less than 0.05). These results suggest that hypothermia to 24 degrees C may reduce cerebral infarction and edema formation following middle cerebral artery occlusion in the rat.

Relationship between the timing of aneurysm surgery and the development of delayed cerebral ischemia

A consecutive series of 145 patients with acute aneurysmal subarachnoid hemorrhage (SAH) were operated on within 7 days of SAH and were prospectively evaluated over a 4-year period to determine if the timing of aneurysm surgery influenced the development of delayed cerebral ischemia. All patients were managed with a standardized policy of urgent surgical clipping and treatment with aggressive prophylactic postoperative volume expansion. Patients with delayed ischemic symptoms were additionally treated with induced hypertension. Forty-nine patients underwent surgery on Day 0 or 1 (Group 1) post-SAH, 60 patients on Day 2 or 3 (Group 2), and 36 patients on Days 4 through 7 (Group 3). Postoperative delayed cerebral ischemia developed in 16% of (Group 1) patients, in 22% of Group 2 patients, and in 28% of Group 3 patients. Cerebral infarction resulting from delayed cerebral ischemia developed in only 4% of Group 1 patients, 10% of Group 2 patients, and 11% of Group 3 patients. A bad clinical outcome as a result of delayed cerebral ischemia occurred in one Group 1 patient (2%), two Group 2 patients (3%), and one Group 3 patient (3%). Preoperative grade was not significantly correlated with the incidence or severity of delayed cerebral ischemia at any time interval except that patients in modified Hunt and Hess Grade I or II who underwent surgery on Day 0 or 1 after SAH had no strokes or bad outcomes from delayed cerebral ischemia. This study demonstrates that there is no rationale for delaying aneurysm surgery based on the time interval between SAH and patient evaluation.

Pituitary hemorrhage into a Rathke's cleft cyst

This report describes a case of symptomatic pituitary hemorrhage into a Rathke's cleft cyst in a 25-year-old woman. The literature on pituitary hemorrhage in nonadenomatous sellar tumors is reviewed.

Clinical versus subclinical pituitary apoplexy: presentation, surgical management, and outcome in 21 patients

A retrospective review of 16 consecutive patients with pituitary apoplexy treated over a 10-year period is reported. Eight men and 8 women (mean age, 48 years) underwent transsphenoidal decompression after an average duration of symptoms of 19 days. The diagnosis of pituitary apoplexy was made by the sudden onset of headache (88%), nausea (56%), or meningismus (13%), with or without visual disturbances (75%), in the setting of a sellar tumor on computed tomographic or magnetic resonance imaging scans. Thirteen of 16 patients showed significant improvement of symptoms after surgery (average follow-up, 2.5 years). In addition, 5 patients with clinically silent yet extensive pituitary hemorrhage were treated. Although extensive pituitary hemorrhage often produced fulminant apoplexy, it also presented insidiously over many days with few, if any, clinical signs. Rapid diagnosis, endocrine replacement, and transsphenoidal decompression constituted effective therapy. Magnetic resonance imaging (after at least 12 hours of symptoms) was superior to computed tomography in detecting hemorrhage.

Chronic cerebral blood flow changes following experimental subarachnoid hemorrhage in rats

Experimental subarachnoid hemorrhage was induced in 52 adult male Wistar rats by microsurgical transclival basilar artery puncture. Telencephalic blood flow measured in 24 rats with subarachnoid hemorrhage was compared with that in 23 sham-operated rats and 10 unoperated control rats using the [14C]butanol indicator fractionation technique. Telencephalic blood flow was significantly less in the rats with subarachnoid hemorrhage than in the sham-operated rats 3 (78.7 +/- 6.9 [n = 7] and 112.0 +/- 8.5 [n = 8] ml/100 g/min, respectively; p less than 0.01), 7 (74.9 +/- 5.1 [n = 9] and 112.6 +/- 4.6 [n = 8] ml/100 g/min, p less than 0.001), and 14 (81.9 +/- 6.0 [n = 8] and 104.1 +/- 5.4 [n = 7] ml/100 g/min, p less than 0.01) days after surgery. Telencephalic blood flow in unoperated controls (114.7 +/- 4.9 ml/100 g/min) did not differ significantly from sham-operated rats. Clinically, the 52 rats with subarachnoid hemorrhage were indistinguishable from 32 sham-operated rats. Postmortem examinations in 10 rats used in a preliminary investigation demonstrated significant blood clot in the basal cisterns 2 hours after basilar artery puncture. Intracranial pressure was slightly elevated (2.3 mm Hg over baseline) 30 minutes after the hemorrhage (n = 7), but when measured 3 (n = 3) or 7 (n = 3) days after surgery it had returned to baseline. Histologic examination of the brains from 10 rats subjected to subarachnoid hemorrhage 7 (n = 5) or 14 (n = 5) days before sacrifice revealed no evidence of cerebral ischemia or vasculopathic changes in the cerebral arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral revascularization: a review

A review of the development and current methods of surgical revascularization of the cerebral circulation is presented. In addition to the conventional superficial temporal artery to middle cerebral artery (STA-MCA) bypass, the techniques of interposition vein grafting and vertebrobasilar revascularization are discussed. The results and implications of the International Cooperative Study are reviewed. Extracranial-intracranial (EC-IC) bypass grafting remains an essential procedure in the treatment of many cerebrovascular conditions, including Moya Moya disease and giant intracranial aneurysms. The efficacy of interposition vein grafts, as well as the EC-IC bypass in the treatment of vertebrobasilar insufficiency, acute cerebral ischemia, cerebral vasospasm, and multi-infarct dementia, remains to be determined. Several alternative revascularization procedures, including proximal MCA anastomosis and omental transposition, are in development.

The effects of norepinephrine depletion on cerebral blood flow in the rat

Cerebral blood flow (CBF) was measured by [14C]butanol indicator fractionation in 10 rats given intraventricular injections of 6-hydroxydopamine (6-OHDA) compared to 8 saline-injected controls. Rats treated with 6-OHDA displayed an 83% reduction in cortical norepinephrine (NE) levels. CBF was significantly increased in 6-OHDA-treated rats compared to controls (average whole brain blood flow of 126.0 +/- 8.3 and 97.1 +/- 10.6 ml.min-1.10(-2)g-1 respectively, P less than 0.05). These studies suggest that noradrenergic innervation of the brain and cerebral microvasculature exerts a moderating effect on resting CBF.

Somatostatin immunocytochemistry in the rabbit retina

In previous work, radioimmunoassay was used to document the presence of somatostatin-like immunoreactive material in the rabbit retina. The present study was undertaken to determine the cellular localization of that material by light microscopic immunocytochemistry. Rabbit retinas were fixed by immersion in paraformaldehyde-lysine-periodate and reacted, either as whole retinas or as 50 microns Vibratome cross-sections, with an antiserum directed against somatostatin-14. Consistent staining of neuronal perikarya was seen only in the retinas of rabbits that had been pretreated with intravitreal injections of colchicine. Specifically stained cell bodies are present in the ganglion cell layer; the cells give rise to fibers in both the innermost and outermost sublaminas of the inner plexiform layer. In retinal whole mounts, the cells possess two or three primary dendrites with sparse branching. The dendritic fields are up to 1 mm in diameter, and adjacent dendritic fields overlap. Many cells have a thin varicose process arising from the soma or a proximal primary dendrite; these processes branch repeatedly within the retina and resemble intraretinal axons. The somatostatin-reactive cells may be associational ganglion cells or displaced amacrine cells; it is less likely that they are ganglion cells with axons projecting to the brain.