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Satoru Shimizu, Satoshi Utsuki, Sachio Suzuki, Hidehiro Oka and Kiyotaka Fujii

✓Although the Codman-Hakim programmable valve is popular, several problems arising from its design have been described. The authors report an additional cause of shunt obstruction in the system. A 6-year-old girl who had received a ventriculoperitoneal shunt with the Codman-Hakim programmable valve system presented with worsening consciousness. The valve proved hard to flush, and emergency revision of the valve was performed. Examination of the extracted valve revealed that the pressure control cam had migrated into the outlet of the valve, thus causing the obstruction. A crack in the plastic housing surrounding the cam suggesting a past impact to the system was also revealed. These factors should thus be kept in mind as potential sources of obstruction of the valve system, especially in patients susceptible to episodes of head impact.

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Satoshi Utsuki, Hidehiro Oka, Kimitoshi Sato, Satoru Shimizu, Sachio Suzuki and Kiyotaka Fujii

Peritumoral hemangioblastoma cysts are usually composed of fibrous tissue without tumor cells. The authors describe the first case in which fluorescence with 5-aminolevulinic acid (5-ALA) was used to diagnose a hemangioblastoma tumor in a peritumoral cyst wall. A 27-year-old woman with a homogeneous, enhanced nodular lesion in the right hemisphere of the cerebellum underwent surgical treatment. After the nodular lesion was removed, the cyst region was observed with the aid of a semiconductor laser with a peak wavelength of 405 ± 1 nm, which was powered using a fiberoptic cable. The cyst region was visualized with strong fluorescence, which disappeared after tissue removal. The fluorescent cyst consisted of tumor cells. The authors conclude that fluorescence diagnosis performed using 5-ALA can inform the choice of removing hemangioblastoma cysts.

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Satoshi Utsuki, Hidehiro Oka, Takao Sagiuchi, Satoru Shimizu, Sachio Suzuki and Kiyotaka Fujii

✓ The recurrence of intracranial mature teratomas as germ cell tumors of different histological types is rarely reported. The authors describe the first case of the malignant transformation of an intracranial mature teratoma into a yolk sac tumor in a 16-year-old boy who presented with a 1-month history of anorexia and somnolence. Seven years prior to this presentation, the boy had undergone surgery for extirpation of a mature pineal teratoma. Computed tomography images obtained at his second presentation revealed a homogeneously enhanced mass within the third ventricle. The tumor was resected and the results of a histological examination were consistent with a yolk sac tumor. After resection, the patient underwent radiation therapy followed by chemotherapy with cisplatin and etoposide but died of tumor progression 15 months after his second hospitalization.

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Satoshi Utsuki, Hidehiro Oka, Sumito Sato, Sachio Suzuki, Satoru Shimizu, Satoshi Tanaka and Kiyotaka Fujii

✓The response of nonfluorescing infiltrating tumors that had been exposed to 5–aminolevulinic acid and irradiated using a laser at a wavelength of 405 nm was analyzed intraoperatively using spectroscopy. Histological analyses demonstrated that neoplastic cells were present in the tissue region that displayed a peak at 636 nm, whereas no neoplastic cells were present in the region that exhibited only the excitation light peak. The authors conclude that the intraoperative use of laser spectroscopy can allow the diagnosis of infiltrating tumor and the detection of boundaries of the infiltrate when standard fluorescence techniques fail.

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Satoshi Yamaguchi, Arnold H. Menezes, Kiyoharu Shimizu, Royce W. Woodroffe, Logan C. Helland, Patrick W. Hitchon and Matthew A. Howard III

OBJECTIVE

The differences in symptoms of spinal meningiomas have rarely been discussed from the perspective of tumor characteristics. The main purpose of this paper was to define the differences, if any, in symptoms in patients with spinal meningiomas with respect to tumor size, location, and degree of spinal cord compression. The authors also sought the threshold of spinal cord compression that causes motor weakness.

METHODS

The authors conducted a retrospective study of 53 cases of spinal meningiomas that were surgically treated from 2013 to 2018. Symptoms related to the tumor were classified as motor weakness, sensory disturbance, pain, and bowel/bladder dysfunction. Based on MR images, tumor location was classified by spinal level and by its attachment to the dura mater. Tumor dimensions were also measured. Occupation ratios of the tumors to the spinal canal and degree of spinal cord flattening were sought from the axial MR images that showed the highest degree of spinal cord compression.

RESULTS

Motor weakness and sensory disturbance were significantly more common in thoracic spine meningiomas than in cervical spine meningiomas (p < 0.001 and p = 0.013, respectively), while pain was more common in meningiomas at the craniovertebral junction (p < 0.001). The attachment, height, width, depth, and volume of the tumor showed no significant difference irrespective of the presence or absence of each symptom. In cases of motor weakness and sensory disturbance, occupation ratios and spinal cord flattening ratios were significantly larger. However, these ratios were significantly smaller in the presence of pain. Multivariate logistic regression analysis revealed that occupation ratio independently contributed to motor weakness (OR 1.14, p = 0.035) and pain (OR 0.925, p = 0.034). Receiver operating characteristic curve analysis suggested that occupation ratio with a value of 63.678% is the threshold for the tumor to cause motor weakness.

CONCLUSIONS

The study showed the difference in clinical presentation of spinal meningiomas by spinal level, occupation ratio, and spinal cord flattening ratio. An occupation ratio of approximately 64% could be utilized as the threshold value of tumor growth to cause motor weakness. Tumor growth in the cervical spine might cause pain symptoms before causing motor weakness. The relationship between the tumor and its symptomatology should be discussed with respect to tumor size relative to the surrounding spinal canal.

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Kiyoharu Shimizu, Masaaki Takeda, Takafumi Mitsuhara, Shunichi Tanaka, Yushi Nagano, Hitoshi Yamahata, Kaoru Kurisu and Satoshi Yamaguchi

OBJECTIVE

Spinal dural arteriovenous fistulas (SDAVFs) commonly present with symptoms of myelopathy due to venous congestion in the spinal cord; asymptomatic SDAVFs are rarely encountered. To elucidate the clinical characteristics of asymptomatic SDAVFs, the authors present 5 new cases of asymptomatic SDAVF and report the results of their systematical review of the associated literature.

METHODS

Five databases were systematically searched for all relevant English-language articles on SDAVFs published from 1990 to 2018. The clinical features and imaging findings of asymptomatic SDAVFs were collected and compared with those of symptomatic SDAVFs.

RESULTS

Twenty cases, including the 5 cases from the authors’ experience, were found. Asymptomatic SDAVFs were more prevalent in the cervical region (35.0%); cervical lesions account for only 2% of all symptomatic SDAVFs. The affected perimedullary veins tended to drain more cranially (50.0%) than caudally (10.0%). Four cases of asymptomatic SDAVF became symptomatic, 1 case spontaneously disappeared, and the remaining 15 cases were unchanged or surgically treated.

CONCLUSIONS

The higher prevalence of asymptomatic SDAVFs in the cervical spine might be a distinct feature of asymptomatic SDAVFs. Given that venous congestion is the pathophysiology of a symptomatic SDAVF, abundant collateral venous pathways and unique flow dynamics of the CSF in the cervical spine might prevent asymptomatic cervical SDAVFs from becoming symptomatic. In cases in which venous congestion is avoidable, not all asymptomatic SDAVFs will become symptomatic.

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Kimitoshi Sato, Satoru Shimizu, Satoshi Utsuki, Sachio Suzuki, Hidehiro Oka and Kiyotaka Fujii

✓ Although the Codman Hakim programmable valve (CHPV) system is popular, several problems arising from its design have been described. The authors report an additional cause of shunt failure associated with the use of the CHPV system. A 7-year-old girl who had previously undergone placement of a ventriculoperitoneal shunt with the CHPV system was admitted in a comatose state. Radiography did not demonstrate any breakage or change in the opening pressure of the valve. Manual pumping of the valve resulted in neurological improvement and shrinkage of the girl’s ventricles. However, ventriculomegaly was again observed several hours later, and an emergency valve revision was performed.

The manufacturer’s examination of the extracted valve revealed a crack on the surface of the hard plastic housing covering the valve chamber, which appeared to be suggestive of some type of blunt trauma. In addition, the flat spring that transmitted resistance from the pressure control cam to the valve ball was deformed in such a manner that it caused excessive pressure against the valve ball. Because of this deformity, the actual opening pressure in this patient had reached a maximum level of 226 mm H2O instead of the adjusted pressure of 60 mm H2O. In patients with the CHPV system whose medical history is difficult to ascertain, the possibility of damage to the valve spring and the need for a prompt revision surgery should be considered. The authors conclude that placement of the CHPV system may be contraindicated in patients with a known habit of head banging.

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Satoru Shimizu, Satoshi Utsuki, Kimitoshi Sato, Hidehiro Oka, Kiyotaka Fujii and Kimihiko Mii

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Hiroki Ushirozako, Tomohiko Hasegawa, Shigeto Ebata, Tetsuro Ohba, Hiroki Oba, Keijiro Mukaiyama, Satoshi Shimizu, Yu Yamato, Koichiro Ide, Yosuke Shibata, Toshiyuki Ojima, Jun Takahashi, Hirotaka Haro and Yukihiro Matsuyama

OBJECTIVE

Nonunion after posterior lumbar interbody fusion (PLIF) is associated with poor long-term outcomes in terms of health-related quality of life. Biomechanical factors in the fusion segment may influence spinal fusion rates. There are no reports on the relationship between intervertebral union and the absorption of autografts or vertebral endplates. Therefore, the purpose of this retrospective study was to evaluate the risk factors of nonunion after PLIF and identify preventive measures.

METHODS

The authors analyzed 138 patients who underwent 1-level PLIF between 2016 and 2018 (75 males, 63 females; mean age 67 years; minimum follow-up period 12 months). Lumbar CT images obtained soon after the surgery and at 6 and 12 months of follow-up were examined for the mean total occupancy rate of the autograft, presence of a translucent zone between the autograft and endplate (more than 50% of vertebral diameter), cage subsidence, and screw loosening. Complete intervertebral union was defined as the presence of both upper and lower complete fusion in the center cage regions on coronal and sagittal CT slices at 12 months postoperatively. Patients were classified into either union or nonunion groups.

RESULTS

Complete union after PLIF was observed in 62 patients (45%), while nonunion was observed in 76 patients (55%). The mean total occupancy rate of the autograft immediately after the surgery was higher in the union group than in the nonunion group (59% vs 53%; p = 0.046). At 12 months postoperatively, the total occupancy rate of the autograft had decreased by 5.4% in the union group and by 11.9% in the nonunion group (p = 0.020). A translucent zone between the autograft and endplate immediately after the surgery was observed in 14 and 38 patients (23% and 50%) in the union and nonunion groups, respectively (p = 0.001). The nonunion group had a significantly higher proportion of cases with cage subsidence and screw loosening at 12 months postoperatively in comparison to the union group (p = 0.010 and p = 0.009, respectively).

CONCLUSIONS

A lower occupancy rate of the autograft and the presence of a translucent zone between the autograft and endplate immediately after the surgery were associated with nonunion at 12 months after PLIF. It may be important to achieve sufficient contact between the autograft and endplate intraoperatively for osseous union enhancement and to avoid excessive absorption of the autograft. The achievement of complete intervertebral union may decrease the incidence of cage subsidence or screw loosening.