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Junichi Mizuno and Hiroshi Nakagawa

Object

The goal of this study was to determine the appropriate surgical strategy for cervical spondylosis associated with an early form of ossification of the posterior longitudinal ligament (EOPLL) of the cervical spine.

Methods

Patients with EOPLL-associated cervical spondyosis were selected for treatment. Medical records and radiographs were retrospectively reviewed. Specimens taken at the time of operation were histologically examined. There were 24 men and six women ranging in age from 39 to 74 years (mean 57.6 years). Symptoms consisted of myelopathy in 28 cases and radiculopathy in two cases. Anterior decompressive surgery was performed. The EOPLL, hypertrophy of the posterior longitudinal ligament (HPLL), and the disc–PLL complex were directly resected. The mean preoperative Japan Orthopaedic Association score was 12.6, and the mean postoperative score was 14.4. Histologically, EOPLL was consistent with foci of compact lamellar bone in the degenerative thickening of the PLL.

Conclusions

Appropriate corpectomy should follow direct removal of EOPLL associated with HPLL compressing the spinal cord to achieve good outcomes.

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Daniel L. Barrow, Junichi Mizuno and George T. Tindall

✓ The authors have reviewed the results of transsphenoidal microsurgical management in 69 patients with prolactin-secreting pituitary adenomas who had preoperative serum prolactin levels over 200 ng/ml. The patients were divided into three groups based on their preoperative serum prolactin levels: over 200 to 500 ng/ml (Group A); over 500 to 1000 ng/ml (Group B); and over 1000 ng/ml (Group C). The percentage of successful treatment (“control rate”) was 68%, 30%, and 14%, respectively, in these three groups of patients. Based on these results, the authors offer guidelines for the management of patients with prolactin-secreting pituitary adenomas associated with exceptionally high serum prolactin levels. The surgical control rate of 68% in Group A seems to justify surgery for these patients, while primary medical care with bromocriptine is recommended for most patients with serum prolactin levels over 500 ng/ml.

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Junichi Mizuno, Hiroshi Nakagawa, Tatsushi Inoue and Yoshio Hashizume

Object. The goal of this study was to elucidate the pathophysiological features and clinical significance of the magnetic resonance imaging—documented small intramedullary high signal intensity known as “snake-eye appearance” (SEA) in cases of compressive myelopathy such as cervical spondylosis or ossification of the posterior longitudinal ligament.

Methods. One hundred forty-four patients with compression myelopathy who underwent surgery between 1998 and 2000 were selected. Intramedullary high signal intensity was found in 79 cases and was divided into two types, SEA and non-SEA (NSEA). The Japan Orthopaedic Association (JOA) scoring system was used for evaluation of pre- and postoperative neurological status. In nine cases of SEA autopsy was performed and specimens were histologically analyzed.

The improvement ratio determined by JOA score was 32.2 ± 15.1% in SEA, 47.1 ± 12.1% in NSEA, and 50 ± 18.3% (p < 0.01) in control cases in which high signal intesity was absent. There were significant differences among SEA, NSEA, and control groups. In a separate group of nine patients who died of unrelated causes, histological examination showed small cystic necrosis in the center of the central gray matter of the ventrolateral posterior column and significant neuronal loss in the flattened anterior horn.

Conclusions. Snake-eye appearance was found to be a product of cystic necrosis resulting from mechanical compression and venous infarction. Destruction of the gray matter accompanying significant neuronal loss in the anterior horn suggested that SEA is an unfavorable prognostic factor for the recovery of upper-extremity motor weakness.

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Junichi Mizuno and Hiroshi Nakagawa

Object

This study was designed to determine the surgical technique and surgery-related outcome, fusion rate, and complication of anterior decompression and fusion (with various graft materials) performed in patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine.

Methods

Between 1980 and 1998, 107 patients with radiologically proven OPLL underwent surgery via the anterior approach for direct removal of the ossified mass. Graft materials included iliac crest in 45 cases, vertebral body (VB) in 37 cases; and interbody fusion cages in 25 cases. In four patients with three-level VB grafts and one with a two-level VB graft, anterior plates were placed. Surgery-related outcome was excellent or good in 89% and fair in 11%. This clinical improvement correlated well with the severity of preoperative myelopathy. Only one patient with severe myelopathy due to extensive mixed-type OPLL developed a segmental weakness of the bilateral upper extremities. The overall fusion rate was 97%. Three patients with obvious spinal instability due to pseudarthrosis required reoperation. Of the graft materials used in this series, VB grafts were the most fragile.

Conclusions

The anterior approach is an effective route for decompressing the cervical cord with OPLL. Slight asymptomatic kyphotic deformity may be encountered. Of the graft materials used in our series, VB graft was considered most fragile, and thus least optimal.

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Junichi Mizuno, Hiroshi Nakagawa, Naoki Matsuo and Joonsuk Song

Object. The authors' goal in this study was to understand the frequency and pattern of dural ossification (DO, and to evaluate the effectiveness of neuroimaging modalities used to identify this disease in association with ossification of the posterior longitudinal ligament (OPLL).

Methods. One hundred eleven patients with OPLL underwent anterior procedures. Of these patients, 17 (15.3%) had associated ossification of the dura mater. There were 10 cases of DO in the 94 patients with segmental OPLL and seven in the 17 patients with nonsegmental OPLL (seven continuous and 10 mixed-type OPLL). Retrospective evaluation of DO was performed by examining plain x-ray films, polytomography studies, computerized tomography (CT) scans, and magnetic resonance (MR) images. A positive correlation was found between the type of OPLL and the frequency of DO (p < 0.01).

The DO was classified into the following three types according to shape: 1) isolated type, 2) double-layer type, and 3) en bloc type, based on its relationship with OPLL. There were 10 lesions of the double-layer type, four en bloc type, and three isolated type; the double-layer pattern of DO was the most common. All DOs as well as OPLLs (17 cases) were identified using bone-window CT scanning. Polytomography was used successfully to identify all 12 OPLLs, whereas DO was recognized in seven of the 12 cases. Magnetic resonance imaging could not identify DO (none of the 17 cases), although OPLL was identified on MR imaging in 12 of the 17 cases.

Conclusions. Three patterns of DO associated with OPLL, that is, isolated, double-layer, and en bloc types, were confirmed by retrospective analysis of neuroimaging findings. Nonsegmental OPLL was likely to be accompanied by DO. Bone-window CT scanning was most useful for identification of DO as well as OPLL, whereas MR imaging was ineffective in recognizing DO.

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Hiroshi Nakagawa, Sang-Don Kim, Junichi Mizuno, Yukoh Ohara and Kiyoshi Ito

Object. The authors discuss the safety and efficacy of an ultrasonic bone curette in various spinal surgeries and report its advantages in clinical application.

Methods. Between April 2002 and September 2003, 76 patients with various spinal diseases (29 cervical, five thoracic, 40 lumbosacral, and two foramen magnum regions) were treated microsurgically by using a Sonopet ultrasonic bone curette with longitudinal and torsional tips and lightweight handpieces. The operations were performed successfully and the device was easy to handle. There were no instrument-related complications or -induced damage to any structure even when removing osseous spurs or ossified lesions near the dura mater, nerves, and vessels.

Conclusions. The ultrasonic curette is a useful instrument for procedures performed near the dura mater or other neural tissue without excessive heat production or mechanical injury. This device is recommended for various spinal surgeries in addition to high-speed drills or other tools.

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Junichi Mizuno, Praveen V. Mummaneni, Gerald E. Rodts and Daniel L. Barrow

✓The authors report a case of a recurrent subdural hematoma (SDH) that was caused by a persistent cerebrospinal fluid (CSF) leak from an L1–2 fistula. A 34-year-old man experienced severe headaches due to SDH, and he underwent aspiration of subdural fluid four times due to recurrent collections. Further evaluation with computerized tomography (CT) myelography demonstrated extradural extravasation of contrast through an L1–2 fistula. The patient underwent an L1–2 laminectomy; a small dural defect with CSF leakage at the left nerve root sleeve was found and was repaired. Following the repair, the patient had no further recurrence of SDH. Recurrent SDH, caused by spontaneous CSF leakage through a lumbar CSF fistula, is extremely rare. In cases of recurrent SDH, radiographic workup with spinal CT myelography should be considered.

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Praveen V. Mummaneni, David H. Walker, Junichi Mizuno and Gerald E. Rodts

✓ Transpedicular vertebroplasty has been established as a safe and effective treatment of thoracic and lumbar compression fractures. Complications are rare, and infectious complications requiring surgical management have only been reported once in the literature. The authors present two cases of infectious complications requiring surgical management. They emphasize that systemic infection is a contraindication to the performance of vertebroplasty. The serious nature of these infections, their surgical management, and strategies for avoiding them are discussed.

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Hiroyuki Kayaba, Tatsuzo Hebiguchi, Yasunobu Itoh, Hiroaki Yoshino, Masaru Mizuno, Mayako Morii, Tetsuya Adachi, Junichi Chihara and Tetsuo Kato

Object. Disturbance in anorectal function is a major factor restricting the activities of daily living in patients with spinal cord disorders. To detect changes in anorectal motilities due to a tethered spinal cord, anorectal functions were evaluated using a saline enema test and fecoflowmetry before and after patients underwent untethering surgery.

Methods. The bowel functions in five patients with a tethered cord syndrome (TCS) were evaluated by performing a saline enema test and fecoflowmetry. The contractile activity of the rectum, the volume of infused saline tolerated in the rectum, anal canal pressure, and the ability to evacuate rectal content were examined.

The characteristic findings in anorectal motility studies conducted in patients with TCS were a hyperactive rectum, diminished rectal saline-retention ability, and diminished maximal flow in saline evacuation. A hyperactive rectum was considered to be a major contributing factor to fecal incontinence. In one asymptomatic patient diminished anal squeezing pressure was exhibited and was incontinent to liquid preoperatively, but recovered after surgery. Two patients who underwent surgery for myeloschisis as infants complained of progressive fecal incontinence when they became adolescents. In one patient fecal incontinence improved but in another patient no improvement was observed after untethering surgery.

Conclusions. Fecodynamic studies allow the detection of neurogenic disturbances of the anorectum in symptomatic and also in asymptomatic patients with TCS. More attention should be paid to the anorectal functions of patients with TCS.

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Muneyoshi Yasuda, Hiroshi Nakagawa, Hiroaki Ozawa, Chikage Inukai, Takeya Watabe, Junichi Mizuno and Masakazu Takayasu

This case report presents the unusual holospinal dissemination of a neurenteric cyst, which was successfully treated by fenestration and placement of a subarachnoid-peritoneal (SP) shunt. The patient was a 46-year-old Japanese woman with a history of fourth ventricle neurenteric cysts, which were managed with cyst fenestration in 1996 and 2005. She had been doing well until January 2006, when she developed dizziness and an unsteady gait. A neurological examination revealed a disturbance in the deep sensation of the feet. A neuroimaging evaluation demonstrated multiple cystic lesions in the whole spinal canal, which significantly distorted the spinal cord. Because the spinal cord distortion was the most severe in the lower cervical to upper thoracic areas, a unilateral osteoplastic laminotomy with an endoscopic cyst fenestration was performed in these areas, followed by placement of an SP shunt. The pathological diagnosis was a disseminated neurenteric cyst. There was no malignancy, and the patient has been well, with an improved gait and no signs of peritoneal dissemination, for > 1 year.

The present case showed a unique extent of dissemination, which was most likely a secondary characteristic. Neurenteric cysts are well known for their tendency to recur, and total removal is usually difficult because of adhesion of the cyst membrane to important structures. The lesion also compromises cerebrospinal fluid circulation. Cyst fenestration combined with SP shunt placement might be a treatment option in such a case.