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Hiroshi Nomura, Katsumi Harimaya, Hisaya Orii, Keiichiro Shiba, Takayoshi Ueta and Toru Iwaki

✓ The authors report four cases of traumatic neuroma in the cervical nerve root in patients with no history of trauma. In one case the patient presented with intractable pain in the left upper extremity and motor paresis of the left shoulder, and in another case the patient suffered neuropathic pain in the left forearm. In both cases, magnetic resonance (MR) imaging revealed an intradural extramedullary mass lesion in the ipsilateral cervical nerve root; these MR imaging signals were similar to the intensity of the spinal cord. Intraoperatively, fusiform enlargement of the anterior cervical nerve root was detected in the subarachnoid space. Histological examination showed a meandering change of axons accompanied by mild axonal swelling and a thin myelin sheath, which are consistent with the typical pathological features of traumatic neuroma. Postoperatively, pain resolved in both cases. The authors also investigated two traumatic neuromas of the anterior cervical nerve root in autopsy cases in which there was no history of trauma and no significant neurological signs suggestive of traumatic neuroma.

The authors conclude that traumatic neuroma of the anterior cervical nerve root may develop following an unnoticed minor brachial plexus injury at birth or a forgotten traction injury of the upper extremity in childhood, and the lesion may be accompanied by various case-specific clinical features.

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Katsumi Harimaya, Keiichiro Shiba, Hiroshi Nomura, Toru Iwaki and Yoshiharu Takemitsu

✓ The authors report a case of ossification of the posterior atlantoaxial membrane that led to the development of cervical myelopathy. Computerized tomography and magnetic resonance imaging were helpful in establishing the diagnosis, and decompressive laminectomy may be an appropriate intervention.

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Nobuaki Tsukamoto, Takeshi Maeda, Hiromasa Miura, Seiya Jingushi, Akira Hosokawa, Katsumi Harimaya, Hidehiko Higaki, Kousaku Kurata and Yukihide Iwamoto

Object

Mechanical stress has been considered one of the important factors in ossification of the spinal ligaments. According to previous clinical and in vitro studies, the accumulation of tensile stress to these ligaments may be responsible for ligament ossification. To elucidate the relationship between such mechanical stress and the development of ossification of the spinal ligaments, the authors established an animal experimental model in which the in vivo response of the spinal ligaments to direct repetitive tensile loading could be observed.

Methods

The caudal vertebrae of adult Wistar rats were studied. After creating a novel stimulating apparatus, cyclic tensile force was loaded to rat caudal spinal ligaments at 10 N in 600 to 1800 cycles per day for up to 2 weeks. The morphological responses were then evaluated histologically and immunohistochemically.

After the loadings, ectopic cartilaginous formations surrounded by proliferating round cells were observed near the insertion of the spinal ligaments. Several areas of the cartilaginous tissue were accompanied by woven bone. Bone morphogenetic protein–2 expression was clearly observed in the cytoplasm of the proliferating round cells. The histological features of the rat spinal ligaments induced by the tensile loadings resembled those of spinal ligament ossification observed in humans.

Conclusions

The findings obtained in the present study strongly suggest that repetitive tensile stress to the spinal ligaments is one of the important causes of ligament ossification in the spine.

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Hirokazu Saiwai, Seiji Okada, Mitsumasa Hayashida, Katsumi Harimaya, Yoshihiro Matsumoto, Ken-ichi Kawaguchi, Kazu Kobayakawa, Takeshi Maeda, Hideki Ohta, Kenzo Shirasawa, Kuniyoshi Tsuchiya, Kazumasa Terada, Kouzo Kaji, Takeshi Arizono, Taichi Saito, Masami Fujiwara, Yukihide Iwamoto and Yasuharu Nakashima

OBJECTIVE

Compression of the spinal cord by thoracic ossification of the posterior longitudinal ligament (T-OPLL) often causes severe thoracic myelopathy. Although surgery is the most effective treatment for T-OPLL, problems associated with surgical intervention require resolution because surgical outcomes are not always favorable, and a small number of patients experience deterioration of their neurological status after surgery. The aim of the present study was to examine the surgery-related risk factors contributing to poor clinical outcomes for myelopathy caused by T-OPLL.

METHODS

Data were extracted from the records of 55 patients with thoracic myelopathy due to T-OPLL at institutions in the Fukuoka Spine Group. The mean follow-up period was 5.3 years. Surgical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scale. To investigate the definitive factors associated with surgical outcomes, univariate and multivariate regression analyses were performed with several patient-related and surgery-related factors, including preoperative comorbidities, radiological findings, JOA score, surgical methods, surgical outcomes, and complications.

RESULTS

Neurological status improved in 33 patients (60.0%) and deteriorated in 10 patients (18.2%) after surgery. The use of instrumentation was significantly associated with an improved outcome. In the comparison of surgical approaches, posterior decompression and fusion resulted in a significantly higher neurological recovery rate than did anterior decompression via a posterior approach and fusion or decompression alone. It was also found that postoperative neurological status was significantly poorer when there were fewer instrumented spinal levels than decompression levels. CSF leakage was a predictable risk factor for deterioration following surgery.

CONCLUSIONS

It is important to identify preventable risk factors for poor surgical outcomes for T-OPLL. The findings of the present study suggest that intraoperative CSF leakage and a lower number of instrumented spinal fusion levels than decompression levels were exacerbating factors for the neurological improvement in T-OPLL surgery.