Odontoid compression of the brainstem without basilar impression-- "odontoid invagination".

We report five patients with odontoid invagination, in which the odontoid process bulges upward into the foramen magnum and compresses the brainstem without deformity of the occipital bone. Two patients had a craniovertebral abnormality associated with Chiari malformation without instability of the craniovertebral junction (stable odontoid invagination). The other three patients had dislocation of the craniovertebral junction due to iatrogenic destruction of the occipital condyle, rheumatoid arthritis or an anomaly of C2 (unstable odontoid invagination). Patients with stable odontoid invagination underwent a transoral odontoidectomy followed by occipitocervical fixation. Those with unstable odontoid invagination underwent cervical traction followed by posterior fixation in reducible cases, while in irreducible cases odontoidectomy with subsequent occipitocervical fixation was performed. Decompression of the neuraxis together with symptomatic improvement was achieved in all patients and none became unstable or developed new symptoms during follow-up ranging from 3 to 15 years.

Thoracic dumbbell intra- and extramedullary schwannoma.

We present a rare case of a solitary dumbbell intra- and extramedullary schwannoma of the thoracic spine in a 54-year-old man without signs of von Recklinghausen's disease. The patient presented with motor weakness in the left lower extremity, bilateral sensory impairment below the T9 dermatome and rectovesical dysfunction. Preoperative magnetic resonance imaging was suspicious for an intradural extramedullary tumor. At operation, the tumor was located posteriorly, at the midline, with no relationship to the posterior nerve roots and was firm and adherent to the adjacent spinal cord, which surrounded the intramedullary portion of the tumor. The intramedullary mass was completely removed with sharp dissection after removal of the extramedullary mass. Surgery resulted in minimal postoperative neurological deficits. These tumors may arise from the Schwann cells of the nerve plexus surrounding vessels in the posterior median sulcus and thus may grow in both an intra- and extramedullary fashion. The optimal treatment of these schwannomas is total removal.

Postoperative vasospasm of unruptured paraclinoid carotid aneurysms: analysis of 30 cases.

This study was conducted to determine the incidence, severity, and causes of delayed vasospasm after clipping of unruptured paraclinoid aneurysms of the internal carotid artery (ICA). A retrospective analysis was made of 30 patients, who underwent clipping of unruptured paraclinoid aneurysms in our institution between 1991 and 1998. We compared angiograms before and after operation and classified them into two groups: vasospasm group and non-vasospasm group. Eleven variables were assessed as to their relationship to delayed vasospasm. There were 9 patients (30%) in the vasospasm group, of which 3 patients (10%) were clinically symptomatic. For all symptomatic patients, aggressive treatment, including triple-H therapy, was conducted with good outcome. The number of clips used (p<0.04) and temporary occlusion of the ICA (p<0.005) were statistically significant factors associated with the incidence of vasospasm. It is suggested that mechanical stimulation to the vascular wall of the ICA is responsible for causing spasm in addition to intraoperative bleeding around the dural ring.

Surgical experience with resection en bloc of intramedullary astrocytomas and ependymomas in the cervical and cervicothoracic region.

We performed 8 operations on 7 patients with benign intramedullary astrocytomas and ependymomas in the cervical and cervicothoracic region. All patients initially underwent gross total tumor resection en bloc. One patient with an astrocytoma showed tumor recurrence postoperatively, and underwent a second operation resulting in subtotal removal. The follow-up after the initial surgery ranged from 2.7 to 19.7 years (mean 8.5 years). Symptomatic improvement was observed in 6 patients after the initial operation. Two patients showed postoperative neurological deterioration, one with an ependymoma and the other after the second operation. No operative complications or deaths, nor postoperative respiratory dysfunction occurred. Benign intramedullary astrocytomas and ependymomas of the cervical and cervicothoracic spinal cord can be treated by radical resection en bloc with a low morbidity and recurrence, as well as acceptable outcomes. We describe here the surgical technique for en bloc tumor removal.

Symmetric dumbbell ganglioneuromas of bilateral C2 and C3 roots with intradural extension associated with von Recklinghausen's disease: case report.

BACKGROUND: Ganglioneuromas are rare benign tumors arising most commonly from the sympathetic nervous system. They occasionally grow in a dumbbell fashion extending into the spinal canal extradurally. However, ganglioneuromas of the cervical spine with intradural extension or multiple locations or in association with von Recklinghausen's disease are rare. CASE DESCRIPTION: A 35-year-old man with von Recklinghausen's disease presented with tetraparesis and respiratory dysfunction. Preoperative neuroimaging revealed an intradural mass extending from the foramen magnum to the C4 vertebral level, as well as bilateral extravertebral extension connecting it with bilateral paraspinal lesions in a dumbbell fashion. Four intradural tumors associated with the bilateral C2 and C3 nerves and located ventrally were removed, leaving the intraforaminal and extradural portion intact. The procedure resulted in postoperative symptomatic improvement. Second, extravertebral tumors of the left neck, which were not related to the cervical sympathetic nerve, were removed. The pathologic diagnosis of the tumors of both the intradural space and cervical neck was ganglioneuroma. CONCLUSION: We present an extremely rare case in an adult with von Recklinghausen's disease who had bilateral, symmetric and multiple dumbbell ganglioneuromas with intradural extension, and also multiple bilateral ganglioneuromas at the neck. The intradural ganglioneuromas were suspected to have originated from the posterior root ganglions of the bilateral C2 and C3 nerves and to have extended ventrally to the spinal cord involving not only sensory but also motor rootlets; the ganglioneuroma of the neck was suspected to have originated from the cervical nerve itself.

Surgical experience of syringomyelia with reference to the findings of magnetic resonance imaging.

We present our surgical experience of 20 patients with syringomyelia, who were divided into two groups based on the findings of magnetic resonance (MR) imaging: a "non-visible cisterna magna" group, in which MR imaging did not reveal cerebrospinal fluid (CSF) in the cisterna magna, and a "visible cisterna magna" group. Patients with non-visible cisterna magna were associated with Chiari malformation (14 patients) or tight cisterna magna (4 patients) and underwent craniocervical decompression. Intradural exploration was performed when CSF movement in the cisterna magna or CSF outflow from the fourth ventricle appeared to be insufficient. It is important to confirm CSF outflow from the foramen of Magendie. Patients with visible cisterna magna were associated with tuberculous meningitis (2 patients) and underwent shunting procedures. Postoperatively, improvement in symptoms and a reduction in syrinx size were demonstrated in all patients except one. Two patients experienced recurrence of symptoms and syrinx dilatation.

Gross total surgical removal of malignant glioma from the medulla oblongata: report of two adult cases with reference to surgical anatomy.

Surgery was performed on the medulla oblongata of two adult patients with malignant glioma. Gross total resection of the tumors, located laterally or medially in the upper half of the medulla respectively, was achieved. The patient with the medially located tumor experienced significant postoperative neurological deterioration including sleep apnea. The other patient with the laterally located tumor showed symptomatic improvement without respiratory complications. The patient with an anaplastic astrocytoma survived approximately 4 years and the patient with a glioblastoma multiforme approximately 2 years. Although the upper half of the medulla is more critical than the lower half, a lateral approach to the upper half of the medulla appears to be relatively safer than a medial approach. Some cases of focal malignant gliomas in the medulla may be amenable to gross total resection in order to achieve improved outcome. Surgery can be undertaken when a tumor is unilateral and its margin appears relatively clear on magnetic resonance images.

Repeat operations in the management of clival chordomas: palliative surgery.

Some chordomas have a very poor prognosis because of their aggressive growth nature, but the efficacy of repeat operations for these cases has not been well documented. This report concerns 3 patients with aggressive chordoma of the clivus, who underwent operations 6 to 12 times over a period of 8 to 17 years because of symptomatic regrowth. Overall mean interval between repeat operations was 18 months with a range from 5 to 57 months and survival times were 9 to19 years after the first surgery. Main symptoms before each operation were diplopia and visual disturbance. Repeat palliative operations by intentional extradural debulking of the tumour to decompress offending neural structures, as well as maximal removal of the tumour, using appropriate skull base approaches, can mitigate progressive symptoms, and may result in better quality and some prolongation of life, although our patients gradually deteriorated neurologically throughout the clinical course.

Dumbbell C2 schwannomas involving both sensory and motor rootlets: report of two cases.

OBJECTIVE AND IMPORTANCE: Intradural-extradural dumbbell C2 schwannomas are rare. This report concerns two such cases with the intradural compartment located ventral to the spinal cord and involving both sensory and motor rootlets. CLINICAL PRESENTATION: One patient was a 57-year-old woman with sensory disturbances in the right extremities and hyperreflexia in the left extremities. The other patient was a 73-year-old man who presented with tetraparesis, walking disability, atrophy of the nuchal and bilateral shoulder muscles, and pain in the right C2 dermatome. INTERVENTION: The extradural component of the tumor was removed first; next, the intradural component was removed successfully via the posterior approach combined with a C1-C2 laminectomy. The patients experienced symptomatic improvement without further deficits except for sensory impairment of the C2 dermatome in one of the patients. CONCLUSION: Intradural-extradural dumbbell C2 schwannomas can be satisfactorily managed with a posterior approach. Removal of the extradural component and opening of the dural ring of the C2 nerve root are necessary for safe extraction of the intradural ventrally located component after debulking. These tumors may arise extradurally within the nerve sheath, extend intradurally and ventrally toward the spinal cord, and involve both sensory and motor rootlets.

Spontaneous resolution of syringomyelia: report of two cases and review of the literature.

OBJECTIVE AND IMPORTANCE: The natural history of syringomyelia is highly unpredictable, and some patients experience improvement or stabilization without surgery. However, the mechanisms of the formation and spontaneous resolution of syringomyelia remain controversial. This report concerns two patients with syringomyelia who demonstrated spontaneous reductions in syrinx size, accompanied by symptomatic improvement. CLINICAL PRESENTATION: One patient was a 10-year-old girl with syringomyelia associated with a tight cisterna magna and basilar impression, who demonstrated a spontaneous decrease in syrinx size, accompanied by symptomatic improvement, in 22 months. The other patient was a 39-year-old man with syringomyelia associated with a Chiari I malformation, who demonstrated a spontaneous reduction in syrinx size and neurological improvement, accompanied by elevation of the cerebellar tonsils, 6 months after diagnosis. INTERVENTION: The patients were monitored. CONCLUSION: The mechanisms of spontaneous resolution of syringomyelia, as well as the factors leading to the cerebrospinal fluid flow disturbances that cause syringomyelia, may vary. Resolution of foramen magnum lesion-related syringomyelia may be the result of spontaneous correction of the abnormal cerebrospinal fluid flow, as observed in our cases, or of cavity fluid drainage into the spinal arachnoid space because of spinal cord fissuring.

En Bloc removal of soft tumors within the brain parenchyma using spoon retractors: traction-dissection method. Technical note.

BACKGROUND: En bloc removal of soft tumors within the brain parenchyma has rarely been performed. We describe a safe technique for en bloc removal of the tumors using a spoon retractor, which enables retraction while holding the soft mass upward. METHODS: Dissection of a tumor mass is performed under traction of the surrounding brain tissue by retracting the mass using a spoon retractor. A dissection plane is first established in a relatively safe area, not opposite the critical area, after a corticotomy. The dissection plane is then extended toward the critical side. After circumferential dissection of the tumor mass, the dissection is continued spirally into deeper regions by retracting and holding the mass upward using a spoon retractor. In this way, the tumor is removed en bloc. CONCLUSIONS: The traction-dissection method using spoon retractors is useful in performing en bloc removal of soft tumors within the brain parenchyma less invasively and provides an appropriate operating field even at depth, reducing intraoperative bleeding, and in vascular rich tumors, possibly preventing tumor seeding in cases of malignant tumors.

Simple cervical spine traction using a halo vest apparatus: technical note.

BACKGROUND: A halo vest apparatus, commonly used for external immobilization and protection of the cervical spine, offers several advantages. We present here a simple, accurate, easy, and safe cervical traction technique using a halo vest apparatus. METHODS: The distinguishing feature of our technique is that, after application of a halo vest apparatus, the halo crown is distracted gradually and stepwise by turning the bilateral screw bolts that hold the halo crown over a period of one to several weeks. After each of these steps, care must be taken to check neurologic, radiologic, and skin conditions, as well as cranial pin tightening. CONCLUSIONS: This distance control technique can provide a strong and accurate traction force by simply turning the bolts without the risk of overdistraction or the need for bed rest, and can be used in conjunction with radiologic examination and transportation of patients, even those unable to walk. The Sugita head fixation system constitutes a safe and easy way to facilitate surgical management after correction of cervical dislocation.

Syringomyelia without hindbrain herniation: tight cisterna magna. Report of four cases and a review of the literature.

Idiopathic syringomyelia, which is not associated with any definite pathogenic lesions, has been treated mainly by shunting of the syrinx and rarely by craniocervical decompression. The authors report four cases of syringomyelia thought to be idiopathic syringomyelia but treated by craniocervical decompression with favorable results. Syringomyelia was present without hindbrain herniation. In such cases, the subarachnoid space anterior to the brainstem at the level of the foramen magnum is usually open but the cisterna magna is impacted by the tonsils, a condition the authors term "tight cisterna magna." All patients underwent foramen magnum decompression and C-1 laminectomy, and the outer layer of the dura was peeled off. Further intradural exploration was performed when outflow of cerebrospinal fluid (CSF) from the fourth ventricle was deemed to be insufficient. Postoperatively, improvement in symptoms and a reduction in syrinx size were demonstrated in three patients, and a reduction in ventricle size was shown in two. Syringomyelia associated with tight cisterna magna should not be classified as idiopathic syringomyelia; rather, it belongs to the category of organic syringomyelia such as Chiari malformation. A possible pathogenesis of cavitation is obstruction of the CSF outflow from the foramen of Magendie, and the cavity may be a communicating dilation of the central canal. Ventricular dilation may depend on the extent to which CSF drainage is impaired from the foramina of Luschka. These cavities may respond to craniocervical decompression if it results in sufficient CSF outflow from the foramen of Magendie, even in cases with concomitant hydrocephalus.

Arm-down Concorde position: a technical note.

BACKGROUND: When the surgeon's approach is from behind the patient's shoulder via the infratentorial supracerebellar approach in the prone position (Concorde position), the patient's shoulder nearest the surgeon occasionally interferes with the visual route and surgical manipulation. To avoid this difficulty the author developed a modified Concorde position. METHODS: In the prone position, the patient's arm at the surgeon's side hangs down over the head end of the operating table, with elbow flexion supported by an arm-holder. CONCLUSIONS: This arm-down Concorde position provides good access for the surgeon in muscular- or broad-shouldered, short-necked, or obese patients.

Malignant astrocytoma of the conus medullaris treated by spinal cordectomy.

We present a case of malignant astrocytoma of the conus medullaris in a 48-year-old man treated by spinal cordectomy. Preoperative examination revealed a tumor at the T12 to L1 level, and intraparenchymal invasion up to T8. The spinal cord was amputated caudally to the root entry zones of the T9 sensory roots. Additional cordectomies were repeated three times because of tumor infiltration at the cut end. At each procedure, the cord was segmentally transected just caudal to the root entry zones of the p reserving-aid sensory roots to minimize the neural deficit. The final transected level was between T3 and T4, and the cut end did not pathologically reveal any tumor invasion. However, the patient died from tumor recurrence and dissemination. Although the attempt to control the tumor by long segment cordectomy was unsuccessful, spinal cordectomy with wide margin may be a possible treatment for patients with malignant astrocytoma of the conus medullaris presenting with complete deficit below the lesion a nd no dissemination, if in an early stage.

Degloving transfacial approach with Le Fort I and nasomaxillary osteotomies: alternative transfacial approach.

OBJECTIVE: We present surgical results obtained with the use of an alternative transfacial approach to the central cranial base. METHODS: A degloving transfacial approach, which is a combination of the midface degloving procedure, the Le Fort I osteotomy with a pediculated cartilaginous septum, and a nasomaxillary osteotomy, was used in 13 procedures for 8 patients. The lower clivus and upper cervical spine were approached via a submucosal route, without opening of the oropharyngeal mucosa. The wall of the nasopharynx was closed with the mucosa of the bony septum. Several patients had previously undergone other surgical procedures and received radiotherapy. RESULTS: The follow-up periods ranged from 4 months to 6.4 years. The same procedure was repeated three times for one patient, with intervals of 5.5 and 1.5 months, and twice for three patients, with intervals of 8.2, 6.3, and 1.3 years. A maxillary antrotomy or bifrontal craniotomy with removal of the orbital bar was combined with this technique. No significant or insurmountable technical problems were encountered, even among patients who had undergone previous surgery or radiotherapy. CONCLUSION: Our technique is relatively simple, with good cosmetic results, and affords sufficient access to the central cranial base from the frontal base down to the upper cervical spine, especially for epidural lesions located in the midline between the carotid arteries. It offers much lower risks of damage to vital neurovascular structures, as well as of meningeal or pharyngeal infectious problems, wound dehiscence, and cerebrospinal fluid leakage. This procedure can be repeated without any increase in difficulty.