Interstitial spinal-cord oedema in syringomyelia associated with Chiari type 1 malformations.

OBJECT: The pathophysiology of syringomyelia in Chiari type 1 malformations has not been clarified. Oedema-like spinal-cord swelling was recently reported in several pathological conditions, including Chiari type 1 malformations as a pre-syrinx state. However, the role of the pre-syrinx state in the development of syringomyelia is unknown. The purpose of this study is to investigate the parenchymal changes of the spinal cord in syringomyelia associated with Chiari type 1 malformations. METHODS: Pre- and postoperative MRI findings in 14 patients who underwent foramen magnum decompression in our institute were reviewed. The analysis was focused on differences in visualisation of the syrinx between T1- and T2-weighted images and abnormal parenchymal signal changes. There were 6 men and 8 women, aged from 6 to 79 years. No patients showed hydrocephalus. RESULTS: Twelve patients had large and expansive syrinx, whereas 2 patients showed small syrinx confined to the centre of the spinal cord. T2-weighted images displayed significantly larger intramedullary abnormal signal areas. Nine patients showed parenchymal hyperintensity areas around the enlarged central canal or base of the posterior white columns adjacent to the syringomyelic cavity. Such parenchymal hyperintensity areas markedly diminished with reduction of the syrinx after surgery and were considered to be interstitial oedema. CONCLUSIONS: From this study, the interstitial oedema of the spinal cord commonly accompanies syringomyelia with Chiari type 1 malformations. Accumulation of the extracellular fluid due to disturbed absorption mechanisms may play an important role in the pathophysiology of syringomyelia associated with Chiari type 1 malformations.

Factors in neurological deterioration and role of surgical treatment in lumbosacral spinal lipoma.

The purpose of this study was to determine factors that might be involved in neurological deterioration and the role of surgical treatment in patients with lumbosacral spinal lipoma. Pre- and postoperative courses of 34 patients were retrospectively analyzed. The age at surgery ranged from 1 month to 47 years. The records of preoperative neurological status indicated that older patients had more severe deficits, while all 8 asymptomatic patients were under 5 years of age. Motor deficits were noted in 9 patients, in 7 of whom the lipoma extended cranially beyond the L5 level. Transitional-type lipomas were accompanied by more severe deficits (asymptomatic 1, symptomatic 17) than other types (asymptomatic 7, symptomatic 9). Postoperative follow-up periods ranged from 5 months to 13 years. During these periods, 7 of the 8 asymptomatic patients remained neurologically intact. Nine of the 26 symptomatic patients improved. Age, extension of the lipoma in the spinal canal and type of lipoma will influence the preoperative neurological status of the patients. Early untethering surgery is recommended in patients with large lipomas extending beyond the L5 level.

Reevaluation of syringosubarachnoid shunt for syringomyelia with Chiari malformation.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of syringosubarachnoid (S-S) shunting for syringomyelia with Chiari malformation. The authors describe the technical methods of performing the S-S shunt and the clinical results, including shunt malfunction. METHODS: Forty-nine patients underwent S-S shunting. These patients were divided into three groups according to differences in the surgical technique used. Group I patients underwent laminectomy plus midline myelotomy and had a shunt tube placed in the dorsal subarachnoid space. Group II patients underwent laminectomy plus dorsal root entry zone myelotomy and had a shunt tube placed in the dorsolateral subarachnoid space. Group III patients underwent hemilaminectomy plus dorsal root entry zone myelotomy and had a shunt tube placed in the ventrolateral subarachnoid space. RESULTS: Clinical results were generally satisfactory, especially in terms of pain relief, in all three groups. However, 10 patients among Groups I and II required follow-up surgery because of shunt problems; no second surgery was necessary for any patient in Group III. CONCLUSION: The S-S shunt was very effective in deflating the syrinx, and the clinical results were satisfactory. Therefore, even though foramen magnum decompression is a very effective treatment, S-S shunting should be reevaluated and not rejected; it should be considered as one of the major surgical options. To prevent the possibility of cord injury by myelotomy or shunt malfunction, the dorsal root entry zone should be selected as the myelotomy site, and the shunt tube should be inserted into the ventral subarachnoid space at the cervical level.

MRI at 1.5 T of intramedullary ependymoma and classification of pattern of contrast enhancement.

We retrospectively reviewed the MRI findings in 28 patients with an intramedullary spinal cord ependymoma who underwent surgical treatment. There were 26 tumours in the cervical and two in the thoracic spine. T1- and T2-weighted and contrast-enhanced images at 1.5 T were obtained in all cases. T1-weighted imaging showed solid tumour as isointense in 13 patients, high-signal in ten and low signal in five. In contrast, T2-weighted imaging showed all tumours as high signal. Contrast enhancement was heterogeneous 13 patients, homogeneous 10, heterogeneous with cyst wall enhancement in three, and a nodule on a cyst wall was seen in two. Cases with these latter patterns require careful differential diagnosis from astrocytoma or haemangioblastoma.

Syringo-subarachnoid shunt for syringomyelia using partial hemilaminectomy.

Syringo-subarachnoid shunt (S-S shunt) is one of the established surgical procedures for syringomyelia. However, this procedure requires a laminectomy which may lead to spinal column complications. We present a modified form of S-S shunt using a partial hemilaminectomy; a S-S shunt is placed via the dorsal root entry zone into the anterior subarachnoid space which is considered to be an ideal site for the drainage of the syrinx fluid. This technique will decrease the incidence of neuronal and spinal complications after surgery and avoid subarachnoid adhesions around the shunt tube. Between 1992 and 1997, a total of 24 patients with syringomyelia have been treated with this surgical procedure without any complications. Collapse of the syrinx was achieved in all cases. The authors believe that the procedure is an effective surgical treatment for syringomyelia and can be applied safely to adolescent and child cases.

Pediatric syringomyelia with chiari malformation: its clinical characteristics and surgical outcomes.

BACKGROUND: Most reports regarding pediatric syringomyelia have focused not only on Chiari malformation, but also on spinal dysraphism. However, the clinical characteristics of syringomyelia with spinal dysraphism are quite different from those of syringomyelia due to Chiari Type I malformation. The objectives of this study were to identify clinical characteristics of pediatric syringomyelia and to determine whether surgery prevents or corrects the scoliosis associated with syringomyelia. METHODS: We reviewed the records of 16 pediatric patients with syringomyelia and Chiari Type I malformation. The patients' ages ranged from 3 to 15 years, with mean age of 9.8 years. None of the patients had spinal dysraphism. RESULTS: Nystagmus was observed in 2 of the 16 patients, motor weakness in 8 patients, sensory disturbance in 10 patients, and scoliosis in 13 patients. As the initial surgical procedure, foramen magnum decompression (FMD) was performed in seven patients and syringo-subarachnoid (S-S) shunting in nine patients. The motor function improved in 7 of the 8 affected patients, and the sensory disturbance improved in 9 of the 10 affected patients. The magnetic resonance images obtained after the surgery revealed marked decrease of the syrinx size in all patients. Of the 13 patients with scoliosis, 5 showed improvement, 5 stabilization, and 3 deterioration. CONCLUSIONS: Compared with adolescent and adult syringomyelia, pediatric syringomyelia shows a much lower incidence of sensory disturbance and pain, but quite a high incidence of scoliosis. Surgery is effective in improving or stabilizing scoliosis in these patients.

Anterior approach to intramedullary hemangioblastoma: case report.

OBJECTIVE AND IMPORTANCE: Intramedullary spinal cord tumors are generally operated on by using the posterior approach. However, the posterior approach may not be suitable for a tumor in the anterior part of the spinal cord. In this report, we describe a case of a cervical intramedullary tumor that was successfully removed by using the anterior approach. CLINICAL PRESENTATION: A 48-year-old woman presented with lower cranial nerve disturbance and motor weakness of the upper extremities. Magnetic resonance imaging revealed a large extensive syrinx and an intramedullary enhanced tumor at the C6 level. The tumor was located at the left of the anterior part of the spinal cord. INTERVENTION: Based on these findings, the anterior approach was used in performing a corpectomy of C5 and C6. The tumor was highly vascular and was resected without resulting in any operative deficits. The pathological diagnosis was hemangioblastoma. CONCLUSION: The present case suggests that the anterior approach is an important option among surgical approaches to the intramedullary tumor in cases in which the tumors are small in size and are located in the anterior part of the cervical cord.

Anterior approach for dumbbell type cervical neurinoma.

A one-stage anterior approach was performed in four patients for total removal of dumbbell type neurinoma at the cervical level. In each case, the neurinoma compressed the spinal cord in the cervical canal, developed anteriorly through the intervertebral foramen, and compressed the vertebral artery. A conventional cervical anterior approach at the tumor site was performed, followed by confirmation of the tumor located outside the spinal canal. After identification of the vertebral artery, corpectomy was carried out and the extradural component of the tumor was resected. In cases with a portion of the tumor located also within the dura mater, the dura mater was opened for removal of the intradural tumor. We found the anterior approach to be effective for the total removal of some kinds of cervical dumbbell type neurinomas.

Diagnosis of spinal cord ependymoma and astrocytic tumours with magnetic resonance imaging.

Ependymoma and astrocytic tumours, both originating from the glial tissue, constitute the majority of intramedullary spinal cord tumours. The purpose of this study is to evaluate the diagnostic ability of magnetic resonance imaging (MRI) in these two types of intramedullary spinal cord tumours. MRI findings of 17 ependymomas and 11 astrocytic tumours of the spinal cord were reviewed. Pre-contrast T(1)-weighted images revealed abnormal enlargement of the spinal cord in all cases. Peritumoural cyst formation was noted in 14 ependymomas (82%) and four astrocytic tumours (36%). Evidence of haemorrhage was identified in five (29%) ependymomas and one (9%) astrocytic tumour. Gadolinium-MRI (Gd-MRI) revealed marked enhancement in 11 ependymomas (65%), while six ependymomas showed irregular, partial or no enhancement. Five of these six ependymomas had evidence of prior haemorrhage. Eight astrocytic tumours (73%) were enhanced on Gd-MRI and the pattern of enhancement was more irregular or partial than that of ependymomas. Two pilocytic astrocytomas showed marked ring-like enhancement. In conclusion, detection of haemorrhage and Gd-MRI will help to differentiate these two types of tumours. Further study will be needed to elucidate the relationship between the histological subtypes of the tumours and MRI findings. Copyright 1999 Harcourt Publishers Ltd.

Spinal intrathecal actinomycosis: a case report.

BACKGROUND: Actinomycosis of the central nervous system is a rare disease that most frequently forms cerebral abscesses. In the present report, we describe an extremely rare case of spinal intrathecal actinomycosis. CASE PRESENTATION: A 33-year-old man presented with high fever followed by back pain and paraparesis. Magnetic resonance imaging (MRI) with gadolinium-diethylene-triamine penta-acetic acid (Gd-DTPA) enhancement (Gd-MRI) displayed an irregularly enhanced mass lesion at the thoraco-lumbar junction that mimicked an intramedullary tumor with exophytic growth. Surgical exploration 7 months after the onset of the high fever revealed intrathecal granulation tissue with small abscess formation. Another surgical exploration was carried out 2 months after the first operation because the patient developed progressive paraparesis and showed an intrathecal ring-like enhancement that was detected with Gd-MRI. Actinomyces organisms were finally identified histologically in the surgical specimen. CONCLUSIONS: The clinical course and serial changes of Gd-MRI findings are important considerations when this rare and infectious spinal lesion is suspected.

Spontaneous shrinkage of lumbosacral lipoma in conjunction with a general decrease in body fat: case report.

OBJECTIVE AND IMPORTANCE: We describe a rare case of a lumbosacral lipoma that shrank spontaneously in parallel to a general loss of body fat. Although early prophylactic surgery is generally recommended for lumbosacral lipomas, the observation made in this case may provide an important implication regarding the conservative management of this disorder. CLINICAL PRESENTATION: A 9-year-old male patient with a subcutaneous lipoma at the sacral level was found to have a lumbosacral lipoma in the spinal canal and tethered spinal cord, as revealed by magnetic resonance imaging. The patient showed no neurological or urological deficits, except for a mild pes cavus deformity. INTERVENTION: Follow-up magnetic resonance imaging performed 4 years later revealed a significant decrease in the size of the lumbosacral lipoma. The patient became very thin and showed no neurological deterioration during the follow-up period. The shrinkage of the lipoma was considered to be in association with the general loss of body fat. CONCLUSION: The control of body weight may be an important factor in the conservative management of patients with lumbosacral spinal lipomas.

Surgical treatment supposed natural history of the tethered cord with occult spinal dysraphism.

We retrospectively evaluated the pre- and postoperative course of 34 tethered cord patients with occult spinal dysraphism in an attempt to infer the natural history of this disorder and to determine the effectiveness of the surgical treatment. There were 32 cases with lumbosacral lipoma and 2 with tight filum terminale. The age at surgery ranged from 1 month to 47 years old. Eight patients, aged 1 month to 4 years old, were asymptomatic; 26 had neurogenic bladder (26 cases) or motor problems affecting the legs (8 cases). None of the patients older than 5 years of age were asymptomatic. Untethering of the spinal cord was performed in all cases. The postoperative follow-up period ranged from 5 months to 11 years. During these periods, 7 (88%) of the 8 asymptomatic patients remained neurologically intact, 6 (23%) of the 26 symptomatic patients showed improved symptoms, and 15 patients (58%) remained unchanged. These results indicate that the neurological symptoms will appear progressively in the tethered cord patients, and that prophylactic surgery should be considered as early as possible.

Surgical treatment of syringomyelia associated with spinal dysraphism.

Clinical and radiological features of syringomyelia in 15 patients with spinal dysraphism are reported. There were 8 patients with occult spinal dysraphism (lumbosacral lipoma) and 7 with spina bifida aperta (meningomyelocele). Syringomyelia with spinal dysraphism can be radiologically divided into two types according to the dysraphic state. The syrinx in the patients with occult spinal dysraphism occurred immediately rostral to the lipoma and was localized to the lower thoracic to lumbar levels, while in the meningomyelocele patients the syrinx extended from the cervical to the thoracic level. Large syrinx formation was recognized in 1 of the 7 occult spinal dysraphism cases and 3 of the 8 meningomyelocele cases. For syringomyelia with occult spinal dysraphism, 4 patients underwent syringo-subarachnoid shunting (S-S shunt, 2 cases) or syringostomy (2 cases) during an untethering operation. In the case of meningomyelocele, S-S shunts were placed in 2 patients. Collapse of the syrinx was achieved in all 6 patients who underwent S-S shunting or syringostomy. Decreased size of the syrinx was also noted in 3 occult spinal dysraphism patients who underwent untethering operations alone. In conclusion, a large syrinx in the case of spinal dysraphism should be surgically treated. S-S shunting is effective in both types of syringomyelia. Foramen magnum decompression may be an alternative method of surgical treatment for syringomyelia in patients with meningomyelocele.

Vascular mechanisms in the pathophysiology of human spinal cord injury.

Vascular injury plays an important role in the primary and secondary injury mechanisms that cause damage to the acutely traumatized spinal cord. To understand the pathophysiology of human spinal cord injury, the authors investigated the vascular system in three uninjured human spinal cords using silicone rubber microangiography and analyzed the histological findings related to vascular injury in nine acutely traumatized human spinal cords obtained at autopsy. The interval from spinal cord injury to death ranged from 20 minutes to 9 months. The microangiograms of the uninjured human cervical cords demonstrated new information about the sulcal arterial system and the pial arteries. The centrifugal sulcal arterial system was found to supply all of the anterior gray matter, the anterior half of the posterior gray matter, approximately the inner half of the anterior and lateral white columns, and the anterior half of the posterior white columns. Traumatized spinal cord specimens in the acute stage (3-5 days postinjury) showed severe hemorrhages predominantly in the gray matter, but also in the white matter. The white matter surrounding the hemorrhagic gray matter showed a variety of lesions, including decreased staining, disrupted myelin, and axonal and periaxonal swelling. The white matter lesions extended far from the injury site, especially in the posterior columns. There was no evidence of complete occlusion of any of the larger arteries, including the anterior and posterior spinal arteries and the sulcal arteries. However, occluded intramedullary veins were identified in the degenerated posterior white columns. In the chronic stage (3-9 months postinjury), the injured segments showed major tissue loss with large cavitations, whereas both rostral and caudal remote sites showed well-demarcated necrotic areas indicative of infarction mainly in the posterior white columns. Obstruction of small intramedullary arteries and veins by the initial mechanical stress or secondary injury mechanisms most likely produced these extensive white matter lesions. Our studies implicate damage to the anterior sulcal arteries in causing the hemorrhagic necrosis and subsequent central myelomalacia at the injury site in acute spinal cord injury in humans.

Laboratory diagnosis of anemia and related diseases using multivariate analysis.

To establish a simple computer program for the laboratory diagnosis of anemia and related diseases, multivariate analyses were applied to the results of routine hematological laboratory tests obtained from 48 patients and 51 healthy volunteers. The patients studied were limited to those who had not been treated hematologically by the time of their first visit to our hospital, and their first data obtained in our laboratory were analyzed. Final diagnoses were aplastic anemia (AA) in 21, myelodysplastic syndrome (MDS) in 14, iron deficiency anemia (IDA) in 3, polycytemia vera (PV)in 3, and idiopathic thrombocytopenic purpura (ITP) in 7. Eight parameters, WBC, RBC, Hb, Ht, MCV, MCH, MCHC, and PLT, were transformed to normal distribution and then applied to principal component analysis to evaluate their independence. Very close relationships were observed between Ht and Hb, and between MCV and MCH. One each of these pairs was selected by discriminant analysis and two sets, RBC, MCH, Hb, PLT, and WBC, and RBC, MCV, Ht, PLT, and WBC, were obtained. Two canonical components gave good discrimination of these five diseases and also of normal subjects. When disease prediction was made using this analysis, 37 of 48 patients (77.1%) were predicted correctly, and furthermore, when two disease predictions were allowed, all patients were diagnosed properly. Some overlaps were observed in this two-dimensional coordinate system, especially of AA and MDS, and also with normal subjects. To improve the system further, the additional parameters of age and sex were added to construct a three-dimensional analysis which resulted in much clearer discrimination. The whole procedure described is being developed with subjects who are not taking medication. Subsequently, the general application of this analytical procedure should be limited to only those not on medications. In conclusion, this is in essence a demonstration project; however, this trial of laboratory diagnosis using routine hematological laboratory results appears to be promising. Further extension of the study by increasing numbers of patients and disorders studied, including secondary anemias, will allow the design of diagnostic software for use with personal computers at the sites of primary care.

[Clinical study of intraspinal neoplasms in children].

The authors report a series of 10 children under 15 years of age with primary intraspinal neoplasm who underwent surgical resection from 1981 to 1994. The tumors consisted of 4 intramedullary tumors (myxopapillary ependymoma, pilocytic astrocytoma, subpial liporna, cavernous angioma), 2 intradural extramedullary tumors (2 neurinomas), and 4 extradural tumors (ganglioneuroma, chordoma, osteochondroma, rhabdomyosarcoma). The initial symptoms in these patients were gait disturbance (50%), weakness of lower extremities (50%), pain (40%), weakness of upper extremities (10%), and tetraparesis (10%). The neurological findings on admission in these patients revealed motor paresis (90%), sensory disturbance (60%), abnormality of deep tendon reflex (60%), pathological reflex (30%), neurogenic bladder (30%), and Lasegue's sign (10%). All patients were treated surgically; laminectoy was performed in 8 patients, laminoplasty in one patient, and transoral approach in one patient. Five patients (50%) underwent a grossly total resection, 3 (30%) had a subtotal resection, and 2 (20%) had a partial resection. Mean follow-up period was 5.6 years. One (10%) patient died due to recurrence and dissemination of the tumor at eight months after surgery in a case of rhabdomyosarcoma. 9 (90%) have had no recurrent tumor and have improved neurologically. In 4 patients (40%) spinal deformity developed, and 2 patients required operative treatment for the spinal deformity. We emphasized the advantage of laminoplasty to prevent postoperative spinal deformity in children.

Surgical indication and results of foramen magnum decompression versus syringosubarachnoid shunting for syringomyelia associated with Chiari I malformation.

Several surgical procedures have been used for the treatment of syringomyelia associated with Chiari I malformation at our institute. The purpose of this article is to evaluate the results of two major surgical procedures, foramen magnum decompression (FMD) and syringosubarachnoid (SS) shunting. The series consisted of 70 patients with syringomyelia associated with Chiari I malformation who were surgically treated. Their ages ranged from 3 to 59 years (median, 29.4 yr). FMD was performed on 33 patients, and SS shunting was performed on 37 patients. The follow-up period ranged from 6 months to 12.5 years, with a mean of 60 months. The clinical and radiological outcomes were analyzed comparing the two groups. We principally performed FMD in patients with symptoms of Chiari I malformation and/or a small syrinx. We prefer to use SS shunting in patients with large syringes. Postoperative magnetic resonance imaging demonstrated that the syrinx had collapsed or decreased in size in 94% of the patients who underwent FMD and in 100% of the patients who underwent SS shunting. Neurological improvements were observed in 82% and in 97% of the patients who underwent FMD and SS shunting, respectively. In particular, the relief of pain was more fully achieved after SS shunting than after FMD. The average time for the syrinx to collapse was 6.3 weeks after surgery in the FMD group and 1.8 weeks in the SS shunting group. These results indicate that clinical symptoms and radiological findings improved much more quickly in the SS shunting group than in the FMD group.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of radiotherapy in the management of spinal cord glioma.

PURPOSE: To determine the role of radiotherapy in the management of spinal cord gliomas. METHODS AND MATERIALS: Thirty-six patients with spinal cord glioma treated between 1979 and 1993 were examined. The patients had 13 astrocytic tumors (7 astrocytomas, 4 anaplastic astrocytomas, 2 glioblastomas), 22 ependymal tumors (18 ependymomas, 4 myxopapillary ependymomas), and 1 unclassified glioma. Fifteen of the patients were treated by surgery alone, but the remaining 21 patients also received postoperative radiotherapy. Total resection was performed on 1 astrocytoma and 13 ependymomas. In general, 40-50 Gy/16-20 fractions/4-5 weeks were given after parital resection, but no radiotherapy was given after total resection. RESULTS: Actuarial survival was significantly better for patients with ependymal tumors than for those with astrocytic tumors (p = 0007), 5-year actuarial survival rates being 96% and 50% for patients with ependymal tumors and astrocytic tumors, respectively. For patients with ependymal tumors, there was no difference in motor function and survival between those with total resection and those with partial resection followed by radiotherapy. Actuarial 3-year survival was 80% for patients with astrocytomas and 40% for those with anaplastic astrocytomas plus glioblastomas. The difference in the degree of motor function between the patients treated with radiotherapy and those without radiotherapy was not statistically significant. One anaplastic astrocytoma and one glioblastoma patient have lived longer than 4 years after radical treatment including radiocordectomy, or irradiation using doses larger than the tolerance threshold of the spinal cord. CONCLUSION: Postoperative conventional radiotherapy is indicated after less than total resection of low-grade ependymal tumors and astrocytomas but not after total resection of ependymomas. Radiocordectomy may be an option for certain cases with high-grade astrocytic tumors.

Spinal cord evoked potential monitoring after spinal cord stimulation during surgery of spinal cord tumors.

Spinal cord evoked potentials (SCEPs) after spinal cord stimulation were used as a method of spinal cord monitoring during surgery of 6 extramedullary and 14 intramedullary spinal cord tumors. SCEPs were recorded from an epidural electrode placed rostral to the level of the tumor. Electrical stimulation was applied on the dorsal spinal cord from a caudally placed epidural electrode. The wave forms of SCEPs consisted of a sharp negative peak (N1) in 15 cases and two negative peaks (N1 and N2) in 5 cases. The N2 wave was markedly attenuated by posterior midline myelotomy, whereas the N1 activity showed less-remarkable changes by myelotomy. An increase in N1 amplitude was observed after the removal of the tumor in four extramedullary and three intramedullary cases. Of six patients that showed decreased N1 amplitude after the removal of the tumor, five patients developed postoperative motor deficits. However, there were four false-negative cases and one false-positive case in regard to changes of N1 amplitude and postoperative motor deficits. Four false results occurred in intramedullary cases. In two of them, postoperative symptoms indicated intraoperative unilateral damage to the spinal cord. The position of the stimulating electrode, the difference in thresholds of the axons for electrical stimulation between the right and left side of the spinal cord, or the change of the distance between the electrode and the spinal cord surface may account for these false results. Thus, our analysis of the changes of SCEP wave forms and early postoperative symptoms indicates that the sensitivity of this monitoring method to detect intraoperative insults to the spinal cord is unsatisfactory in spite of the reproducible wave forms. We conclude that SCEP monitoring can be used as an alternative method or in combination with other types of evoked potentials in patients with severe spinal cord lesions who show abnormal somatosensory evoked potentials preoperatively.

[Intraoperative monitoring for spinal cord tumor by spinal cord evoked potential following unilateral spinal cord stimulation].

We described our experiences with intraoperative spinal cord monitoring in 6 cases of spinal cord tumor. During the operation, spinal cord evoked potential following unilateral spinal cord stimulation was recorded from subdural monitoring electrodes. This series included two cases of intradural extramedullary tumor (one case each of neurinoma and of meningioma) and four cases of intramedullary tumor (2 cases of cavernous angioma, one case each of ependymoma, and of glioblastoma multiforme). Before the removal of the tumor, the spinal cord evoked potential showed lower amplitude or no response on the more affected side in all 6 cases. During the operation, the different intraoperative changes were shown on each side. The authors think that the detection of unilateral damage to the spinal cord is possible in spinal cord evoked potential using unilateral spinal cord stimulation.