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Shinji Hotta, Akio Morita, Atsushi Seichi and Takaaki Kirino

✓ The authors report an unusual case of a patient with combined vertebral artery and Chiari malformation anomalies. Unless such anomalies are properly recognized prior to decompression and fusion, this condition can have grave surgical consequences. The diagnostic and surgery-related implications of such anomalous codiseases are discussed.

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Atsushi Seichi, Katsushi Takeshita, Hiroshi Kawaguchi, Naohiro Kawamura, Akiro Higashikawa and Kozo Nakamura

✓ The authors describe an anterior decompression procedure for thoracic ossification of the posterior longitudinal ligament (PLL) in which they used an image guidance system in three cases. To make registration possible in anterior thoracic surgery, they devised a surgical reference frame that could be connected to a rod and attached to an external fixation device, which was then attached to the thoracic VB.

The mean fiducial error at the registration was acceptable (range 0.5–0.8 mm). They were able to confirm the success of decompression on postoperative computerized tomography scans. In the removal of an ossified thoracic PLL, an image guidance system has been shown to be a useful tool.

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Atsushi Seichi, Susumu Nakajima, Katsushi Takeshita, Tomoaki Kitagawa, Toru Akune, Hiroshi Kawaguchi and Kozo Nakamura

Object

The purpose of this study was to evaluate the advantages of using an image guidance system to aid in the resection of ossified of the ligamentum flavum (OLF) in the thoracic spine. The procedure and surgery-related outcome are discussed.

Methods

Ten patients with myelopathy underwent laminotomy with medial facetectomy and an image guidance system was used to remove the OLF. No neurological deterioration occurred, and postoperative computerized tomography scanning demonstrated successful decompression and good preservation of the lateral parts of the facet joints.

Conclusions

The image guidance system allows accurate resection of the OLF while preserving as much as possible the facet joints and posterior elements of the thoracic spine.

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Motoaki Murakami, Atsushi Seichi, Hirotaka Chikuda, Katsushi Takeshita, Kozo Nakamura and Atsushi Kimura

The authors report the case of a man with cervical ossification of the posterior longitudinal ligament (OPLL) who was observed for more than 26 years. Initial symptoms consisted of subtle numbness of the hands, and initial radiography showed small, segmental-type OPLL in the cervical spine. Lateral radiography of the cervical spine was performed every few years. Ossification accelerated for about 4 years during the follow-up. Segmental-type OPLL developed into mixed-type extensive OPLL. This case shows an accelerating maturation process of OPLL over the course of a few years. Segmental-type OPLL appears to represent an initial stage of extensive OPLL.

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Atsushi Seichi, Hirotaka Chikuda, Atsushi Kimura, Katsushi Takeshita, Shurei Sugita, Yuichi Hoshino and Kozo Nakamura

Object

The aim in this prospective study was to determine the morphological limitations of laminoplasty for cervical ossification of the posterior longitudinal ligament (OPLL) by using intraoperative ultrasonography and to investigate correlations between ultrasonographic findings and 2-year follow-up results.

Methods

Included in this study were 40 patients who underwent double-door laminoplasty for cervical myelopathy due to OPLL. Intraoperative ultrasonography was used to evaluate posterior shift of the spinal cord after the posterior decompression procedure. To determine the decompression status of the cord, the authors classified ultrasonographic findings into 3 types on the basis of the presence or absence of spinal cord contact with OPLL after decompression: Type 1, noncontact; Type 2, contact and apart; and Type 3, contact. Patients were divided accordingly into Group 1, showing Type 1 or 2 findings, representing sufficient decompression; and Group 2, showing Type 3 findings with insufficient decompression. Preoperative sagittal alignment of the cervical spine (C2–7 angle) and preoperative maximal thickness of OPLL were compared between groups. The authors also investigated the morphological limitations of laminoplasty and 2-year follow-up results by using the Japanese Orthopedic Association (JOA) scoring system.

Results

According to receiver operating characteristic curve analysis, an OPLL maximal thickness > 7.2 mm was a cutoff value for insufficient decompression. However, sufficient or insufficient decompression did not correlate with 2-year results, as determined by JOA scores. The C2–7 angle had no impact on ultrasonographic findings.

Conclusions

Laminoplasty has a morphological limitation for thick OPLLs, and a thickness > 7.2 mm represents a theoretical cutoff for residual cord compression after laminoplasty. According to 2-year results, however, laminoplasty can remain the first choice for any type of multiple-level OPLL.

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Shurei Sugita, Hirotaka Chikuda, Katsushi Takeshita, Atsushi Seichi and Sakae Tanaka

Object

Despite its potential clinical impact, information regarding progression of thoracic ossification of the posterior longitudinal ligament (OPLL) is scarce. Posterior decompression with stabilization is currently the primary surgical treatment for symptomatic thoracic OPLL; however, it remains unclear whether thoracic OPLL increases in size following spinal stabilization. It is also unknown whether patients' clinical symptoms worsen as OPLL size increases. In this retrospective case series study, the authors examined the postoperative progression of thoracic OPLL.

Methods

Nine consecutive patients with thoracic OPLL who underwent posterior decompression and fixation with a minimum follow-up of 3 years were included in this study. Thin-slice CT scans of the thoracic spine obtained at the time of surgery and the most recent follow-up were analyzed. The level of the most obvious protrusion of ossification was determined using the sagittal reconstructions, and the ossified area was measured on the axial reconstructed scan at the level of the most obvious protrusion of ossification using the DICOM (digital imaging and communications in medicine) software program. Myelopathy severity was assessed according to the Japanese Orthopaedic Association (JOA) scale score for lower-limb motor function on admission, at postoperative discharge, and at the last follow-up visit.

Results

The OPLL area was increased in all patients. The mean area of ossification increased from 83.6 ± 25.3 mm2 at the time of surgery to 114.8 ± 32.4 mm2 at the last follow-up visit. No patients exhibited any neurological deterioration due to OPLL progression.

Conclusions

The present study demonstrated that the size of the thoracic OPLL increased after spinal stabilization. Despite diminished local spinal motion, OPLL progression did not decrease or stop. Physicians should pay attention to ossification progression in patients with thoracic OPLL.

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Satoshi Ogihara, Atsushi Seichi, Motoshige Iwasaki, Hiroshi Kawaguchi, Tomoaki Kitagawa, Yasuhito Tajiri and Kozo Nakamura

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Ko Matsudaira, Takashi Yamazaki, Atsushi Seichi, Kazuto Hoshi, Nobuhiro Hara, Satoshi Ogiwara, Sei Terayama, Hirotaka Chikuda, Katsushi Takeshita and Kozo Nakamura

The authors developed an original procedure, modified fenestration with restorative spinoplasty (MFRS) for the treatment of lumbar spinal stenosis. The first step is to cut the spinous process in an L-shape, which is caudally reflected. This procedure allows easy access to the spinal canal, including lateral recesses, and makes it easy to perform a trumpet-style decompression of the nerve roots without violating the facet joints. After the decompression of neural tissues, the spinous process is anatomically restored (spinoplasty). The clinical outcomes at 2 years were evaluated using the Japanese Orthopaedic Association (JOA) scale and patients' satisfaction. Radiological follow-up included radiographs and CT.

Between January 2000 and December 2002, 109 patients with neurogenic intermittent claudication with or without mild spondylolisthesis underwent MFRS. Of these, 101 were followed up for at least 2 years (follow-up rate 93%). The average score on the self-administered JOA scale in 89 patients without comorbidity causing gait disturbance improved from 13.3 preoperatively to 22.9 at 2 years' follow-up. Neurogenic intermittent claudication disappeared in all cases. The patients' assessment of treatment satisfaction was “satisfied” in 74 cases, “slightly satisfied” in 12, “slightly dissatisfied” in 2, and “dissatisfied” in 1 case. In 16 cases (18%), a minimum progression of slippage occurred, but no symptomatic instability or recurrent stenosis was observed. Computed tomography showed that the lateral part of the facet joints was well preserved, and the mean residual ratio was 80%. The MFRS technique produces an adequate and safe decompression of the spinal canal, even in patients with narrow and steep facet joints in whom conventional fenestration is technically demanding.