Thoracic outlet syndrome is a complex and controversial entity. We describe one form, the "true" thoracic outlet syndrome, which results from compression of the lower brachial plexus by a medial scalene compressive band. It occurs in patients with a cervical rib or prominent C7 transverse process ; this syndrome is characterized by sensory symptoms and muscle atrophy in the affected limb, and may be diagnosed electrically. The indications for the results of surgery are welldefined. Other forms of thoracic outlet syndrome have been described. These include post-traumatic and vascular forms of outlet syndrome, which are rare. The most controversial entity, "non-specific outlet syndrome" is characterized by sensory symptoms and a normal neurological exam ; there are no objective tests which can unequivocally diagnose this condition. The indications for surgery are poorly defined and controversial.

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With the advent of MR imaging, diagnostic accuracy of spinal neoplasms has been much improved in terms of knowing their location and histology. Location of a spinal tumor is appreciated by the findings of shift of the anatomical landmarks and change of lesion signal. Contrast-enhanced MRI is mandatory to depict small intradural tumors. Although spinal neoplasms are usually classified into extradural, intradural extramedullary and intramedurally types, they sometimes grow in an atypical manner ; that is, subpial location and exophytic growth of an intramedullary tumor. Cyst formation, intratumoral hemorrhage and enhancing pattern are clue for differential diagnosis of intramedullary tumors. To differentiate extramedullary tumors, one should be in mind T1 and T2 signal intensity, homogenous or heterogenouse enhancement (with or without dural tail sign), and CT density. Intradural pathology includes neoplastic and non-neoplastic processes. Intramedullary non-neoplastic lesions tend to involve the spinal cord partly but not entirely. Intramedullary edema extends longitudinally in the spinal cord by sparing the peripheral margin of it. Gray and white matter discrimination is often preserved. Anterior spinal artery syndrome occurs centrally in the anterior two-third of the spinal cord. The lateral and posterior funiculi are involved in multiple sclerosis. In granulomatous myelitis, enhancement is observed along leptomeninges of the spinal cord. Skip lesions, "flip-flop" or lacking of contrast enhancement may suggest non-neoplastic disorders.

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The use of metallic plate and screws in the anterior cervical fusion has become accepted and popular. There exist two different plating systems. However, there has been few attempt to compare surgical morbidity and clinical results either between anterior cervical fusion with and without a plating system or between two different systems in a single series of clinical study. The authors reviewed 117 patients undergoing anterior cervical fusion during the period of January 1992 to September 1996. Simple fusion without a plating system was applied in 55 (group 1), a bicortical non-locked plate screw system in 25 (group 2), and a monocortical locked plate screw system in 37 (group 3). The average follow-up period was about 13.2 months. In group 1, twenty-two patients (40%) with fracture-dislocation or corpectomy required a rigid brace such as halo brace and Minerva cast for 3 months postoperatively and seven patients (13%) experienced graft complications, mainly graft extrusion, while in groups 2 and 3, the patients required only a soft brace for 4 to 8 weeks and no patient experienced serious graft complications like graft extrusion. But two patients of screw breakage, two patients of screw back-out and one patient of non-union were observed in group 2. In comparison of the clinical complications such as hoarseness, there were no significant differences between the groups. In conclusion, a plating system in anterior cervical fusion appears to be safe in spite of its technical demands during the surgery, and to offer postoperative stability in the spine and early ambulation without a rigid brace. A monocortical locked plate screw system appears to have less hardware failure and better surgical results than a bicortical non-locked plate screw system.

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Using computerized motion analysis techniques, kinematics of foot trajectories were quantitatively analyzed in twelve rats before and after dorsal spinal cord hemisection at T6 level. Although overground locomotion in these animals returned to normal within four weeks, some kinematic variables during treadmill locomotion did not recover to pre-lesion levels. Immediately following dorsal hemisection, amplitudes of both hindfeet horizontal and vertical movements were dramatically reduced. However, in three weeks, the amplitudes of horizontal movement (stride length) became significantly larger than that of pre-lesion strides. On the other hand, amplitude of hindlimb vertical movement showed very little recovery. Forelimb-hindlimb coordination was also disrupted initially but returned to normal within three weeks. The duration of hindlimb swing phase became significantly longer after section and gradually recovered, but never to prelesion levels. Interestingly, amplitudes of forelimb vertical movement, which was depressed initially, became significantly larger three weeks after lesion. A dramatic increase in the statistical variation of limb kinematics, which persisted even after motor recovery, is an important parameter for the evaluation of neural deficits in spinal cord injuries. Kinematic analysis using computerized motion analysis techniques is a sensitive technique for the detection of minor motor deficits following nerve injures.

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Posterior spinal instrumentation surgery has been widely employed and highly favored by spinal surgeons as a method for internal fixation of unstable spines. Aggressive surgery applied to spinal diseases has become possible because tight internal fixation is able to be obtained and strict postoperative bed-rest is unnecessary. These benefits are obtained by the developement and improvement of instruments. Their effects are of great benefits for the patients. We have used several instruments for posterior spinal fixation, such as (1) Texas Scottish Rite Hospital system, with pedicle screw, transverse hook and laminar hook in 13 cases, (2) rectangular Luque rod and sublaminar cable and wire in 7 cases, (3) Ransford loop and sublaminar cables for cranio-cervical instability and atlanto-axial dislocation in 4 cases, (4) titanium rod, hook, crosslink and sublaminar cables for posterior spinal fixation in 6 cases, (5) Olerud cervical for posterior cervical fixation in 2 cases. Because of this rather wide experience, we should know the benefits and demerits of spinal instrumentation. It is unnecessary and impossible to be familiar with all instruments, but surgeons should be practiced in using several favorite instruments. Good indication for posterior spinal instrumentation is primary and metastatic spine tumors, vertebral and spinal injuries, cranio-cervical instability, and degenerative spondylolisthesis. In cases of spinal tumor, aggressive removal of the tumor is possible and unstable spine following the tumor removal can be stabilized with internal fixation using instruments. In patients expecting a long survival time, an autologous bone can be used for fixation of the spine in addition to internal fixation. Solid spinal fusion is obtained immediately after the operation, and early rehabilitation is possible even for the elderly.

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Olerud Cervical is a screw and rod fixation system for the whole cervical spine. In this article, we demonstrated our preliminary results using this system. Posterior cervical fixation by Olerud Cervical was performed on ten patients. All patients had cervical instability due to various disorders. There were rheumatoid arthritis in seven, anomaly at upper cervical spine in one, trauma in one and metastasis in one, respectively. The sites of fixation were occipitocervical in four, atlantoaxial in three, lower cervical in two and C1-6 in one, respectively. One patient with metastatic tumor of C3 died two months postoperatively. The other nine patients were followed up for more than twelve months (range, 12-23 months). Bony fusion was achieved in all of these nine patients. There were no major complications. Neither breakage nor dislodgment of implants was observed. However, removal of instruments was needed after bony fusion in one patient, because he complained of neck pain that was supposed to arise from the laterally placed rods. Our preliminary results suggested that Olerud Cervical is a useful implant for posterior cervical fixation. We noted the advantages and disadvantages of this system. The advantages were mechanical superiority available for the whole cervical spine and multiplicity of selection for screw placements, while the disadvantage was the complexity of the implants. It required a great amount of surgical skill to connect the screws and rods.

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Lumbar spinal canal stenosis (LSCS) is one of prevalent crippling diseases of the elderly. In this report, we evaluated surgical results of 36 patients with degenerative LSCS. The patients' ages ranged from 70 to 85 years (average : 74 Y). There were 20 males and 16 females. Surgery was indicated for radiculopathy and/or intermittent claudication resistant to conservative therapy. Interlaminar laminotomies with medial facetectomy (ILMF) were performed for both central canal stenoses (CCS) in 10 cases and lateral recess stenoses (LRS) in 23, while a total facetectomy was carried out for foraminal stenoses (FS) in 2 and a foraminotomy in one. Spondylolisthesis (one degree) was encountered in 11 patients. No spinal fixation was made in the elderly even if spondylolisthesis was coexistent. Surgical decompression was limited to the levels responsible for multiple-level stenoses. As a result, the operative level was single in 61%, double in 36% and triple in 3%. The most common operative level was L4/5 (86%), followed by L5/S (28%), L3/4 (25%) and L2/3 (3%). The short-term evaluation at discharge (average hospital stay : 45 days) showed good resolution of such preoperative symptoms as radicular pains and intermittent claudication in most patients without serious operative complications. However, low back pain or leg pain necessitating analgesics had recurred in 40% of 25 patients who were followed up in the range of 14 to 97 months (average : 3Y2M) after operation, while about 80% of the patients had maintained a good ADL in terms of gait. For the follow-up period, FS recurred in one patient who had undergone a foraminotomy and reoperation was performed in two ; one for a disc hernia at the operative level and the other for FS at one level below. Spondylolisthesis occurred in one patient and progressed in another of 15 patients who were examined by x-ray for a period of 15 to 60 months (average : 2Y5M) postoperatively. No symptomatic aggravation attributable to spondylolisthesis was noted in any of the patients. In conclusion, surgical therapy should be considered for the elderly with a resistant LSCS in expectation of gaining a good ADL, only if the patient has no serious systemic disease. As to the surgical procedure, ILMF is useful for CCS as well as LRS with the advantage of preserving the spinal stability, while a total facetectomy is preferred for FS because of its excellent decompressive effect. Spinal fixation is not commonly indicated for a senile LSCS.

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Surgical advances in the treatment of syringomyelia make it possible to diminish the syringomyelic cavity, but these do not necessarily diminish the patients' problems such as pain. The authors investigated the results of questionnaire to 66 patients with syringomyelia associated with Chiari malformation. The sixty-six patients included 60 adults and 6 children younger than 10 years of age with a mean age of 32.5. Fifty-nine of the patients underwent surgery for the known syringomyelia. Approximately half of the patients were not satisfied with the surgery. Fifty-six patients have experienced some degree of pain, and all of these patients but one are adults. Twenty-six patients felt anxiety about deterioration of their neurological functions as the most frustrating problem related to this disease, and 21 patients experienced intractable pain as the reason for their dissatisfaction. The pain was described as "boring or gnawing", "dull aching", "throbbing", "squeezing" or "piercing". This pain seemed to be aggravated by conditions such as low temperature and high humidity. Distribution of the pain seemed to overlap but to be slightly shifted toward the cephalic level compared with the sensory disturbance distribution. Conventional medical treatments often fail to relieve this kind of intractable central pain, so that further strategies should be devised.

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The surgery for the lesions situated entirely in the ventrolateral quadrant of the spinal cord has been technically challenging. Posterior approach, through a midline incision into the cord, is used most commonly for intramedullary lesions. This approach is not suitable for ventral or ventrolateral lesions of the spinal cord because it would entail extensive dissection of the cord. Although the anterior approach, through vertebrectomy, provides direct visualization of the ventral surface of the spinal cord, the exposure is narrow and deep. In this report, the surgical technique using a posterolateral approach for two hemangioblastomas located in the lateral or ventrolateral part of the spinal cord is described. In both cases, a paramedian skin incision was made on the side of the tumor with the patient in the lateral position. After incision and retraction of the trapezius and paravertebral muscles, the unilateral posterior spinal arch was exposed while keeping supraspinous and interspinous ligament intact. The hemilaminectomy was performed with the removal of the medial two third part of the facet extending one level above and below the extent of the tumor. The spinous processes were minimally undercut with the drill to gain a wider exposure of the dura mater and an enough space to permit spinal cord rotation. A longitudinal dural incision was then made halfway between the root sleeve and the dorsal midline. After opening the dura mater, the posterior and posterolateral surface of the tumor was apparent between the C5 and C6 dorsal nerve roots in Case 1. The tumor in Case 2 was situated entirely in the ventrolateral part of the spinal cord and was accompanied by a cyst and a large syrinx. Although lateral surface of the tumor could not be recognized immediately after opening the dura mater in this case, suction of the cyst and division of the attachment of the dentate ligament to the dura mater yielded to reveal the lateral surface of the tumor under the C5 dorsal nerve root. In both cases, this procedure provided the exposure of the ipsilateral half of the ventral surface of the cord and enabled total removal of these tumors. We think that this approach is useful for lateral and ventrolateral perimedullary and intramedullary lesions of the cervical spinal cord.

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We report a rare case with radiculomyelopathy caused by compression of the upper cervical cord by an anomalous vertebral artery. A 36-year-old man experienced severe pain in the left side of the neck after hyperflexion of the neck and gradually developed weakness of the left upper extremity. Neurological examination disclosed left upper arm monoparesis with paroxysmal severe lancinating pain in the left side of the neck (C2 dermatome), which was evoked by neck flexion and by touch on the left half of the body, and was ameliorated by neck extension. MRIs revealed flow void findings of vertebral arteries which compressed and distorted the spinal cord bilaterally at the level of the atlas. 3D-CT angiogram also showed that the bilateral vertebral arteries entered the spinal canal between the atlas and the axis and made vascular loops in the vertebral canal at the level of the atlas. This anomalous course of the bilateral vertebral arteries was finally confirmed by a vertebral angiongram, but it showed no configuration of fenestration or dissecting aneurysms. The patient was diagnosed as having radiculomyelopathy caused by compression of both the cord and roots by an anomalous vertebral artery and needed to be operated on for decompression. Bilateral vertebral arteries were found to have pierced the dura mater under the posterior arch of the atlas after C1 and C2 laminectomy combined with small suboccipital craniectomy had been carried out. On opening the dura mater, the dorsolateral aspect of the spinal cord appeared to be symmetrically compressed and markedly indented by the bilateral vertebral arteries. To decompress the spinal cord and the dorsal rootlet of C2, the vertebral arteries were repositioned dorsolaterally and anchored to the inner surface of each side of the dura mater by use of 5mm-wide silicon tapes. Postoperatively, the patient's neurological symptoms completely resolved and MRIs and 3D-CT angiogram showed that vascular loops had been satisfactorily dislocated dorsolaterally and the spinal cord had decompressed and regained its normal contour. We emphasize that MRI and 3D-CT angiogram are useful for making a correct preoperative diagnosis and that microsurgical vascular decompression may be the only effective treatment in such a case as this and it should be performed as early as possible.

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Isolated fracture of the lateral mass is rare. We reported the case of a 40-year-old male who fell over a cliff while driving a car. His status was neurologically intact, and the complained only of severe pain in the left side of his neck. Computed tomographic scan of cervical spine revealed a vertical fracture of the lateral mass of the atlas. He was treated using a halo vest for immobilization, and osseous union was achieved successfully. In this case, thin slice CT with bone window provided the correct diagnosis of this injury.

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Thoracic canal stenosis resulting from degenerative changes, such as disc herniation, ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum (OLF) is a well-reported clinicopathological entity. However, compression of the spinal cord caused by hypertrophied articular process in the thoracic region is relatively rare compared with compression in the cervical and lumbar regions. The authors report a case of 75-year-old female who developed subacute thoracic myelopathy after minor traumatic event. CT myelogram (CTM) revealed severe thoracic canal stenosis at the T9-11 levels caused by bilateral facet hypertrophy. Laminectomy including medial facetectomy of T9 through T11 was performed and the patient's neurological deficits were resolved except for a slight numbness in the bilateral distal lower extremities. CTM was more useful than myelogram or MRI for discriminating between this disorder and OLF.

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We report two cases of diffuse idiopathic skeletal hyperostosis (DISH) with dysphagia. The anterior longitudinal ligament was ossified, and had compressed the esophagus in both cases. We performed surgical resection of the ossified anterior longitudinal ligament (OALL) on both patients, and their symptoms were postoperatively ameliorated. The surgical resection of OALL was an effective procedure for dysphagia, though a careful approach is necessary to prevent injury to the esophagus and other soft tissues, since normal anatomical structures are affected by OALL.

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