Yukimi Nishi

MRI of cervical intervertebral discs in asymptomatic subjects

We studied degenerative changes in the cervical intervertebral discs of 497 asymptomatic subjects by MRI and evaluated disc degeneration by loss of signal intensity, posterior and anterior disc protrusion, narrowing of the disc space and foraminal stenosis. In each subject, five disc levels from C2-C3 to C6-C7 were evaluated. The frequency of all degenerative findings increased linearly with age. Disc degeneration was the most common observation, being present in 17% of discs of men and 12% of those of women in their twenties, and 86% and 89% of discs of both men and women over 60 years of age. We found significant differences in frequency between genders for posterior disc protrusion and foraminal stenosis. The former, with demonstrable compression of the spinal cord, was observed in 7.6% of subjects, mostly over 50 years of age. Our results should be taken into account when interpreting the MRI findings in patients with symptomatic disorders of the cervical spine.

Long-term Follow-up Study of Anterior Decompression and Fusion for Thoracic Myelopathy Resulting From Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN This was a retrospective study of the results of anterior decompression and fusion in patients with thoracic myelopathy secondary to ossification of the posterior longitudinal ligament with a minimum follow-up time of 5 years. OBJECTIVES To clarify the effectiveness and limits of anterior decompression and fusion for thoracic ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA Posterior decompression for the surgical management of thoracic ossification of the posterior longitudinal ligament has had an uncertain success record. Anterior decompression and fusion have been considered the treatment of choice however, there are few reports describing the long-term results. METHODS The participants in this investigation were 33 patients whose cases were followed for an average period of 8 years and 2 months. The factors that were investigated included changes in the Japanese Orthopedic Association score and in recovery rates, postoperative complications, and radiographic findings of bone union and progression of ossification of the posterior longitudinal ligament within the area of anterior decompression. RESULTS Although the recovery rates were relatively stable from 1-5 years after surgery, the rates declined thereafter. The average recovery rate at the final follow-up visit was 53.2%. Postoperative complications included three cases of deterioration of thoracic myelopathy and four cases of extrapleural cerebrospinal fluid leakage. Except for the one case of deterioration of thoracic myelopathy, the remainder of the complications were transient. CONCLUSIONS Anterior decompression and fusion is an effective surgical procedure for thoracic ossification of the posterior longitudinal ligament with good, stable, long-term results; when thoracic ossification of the posterior longitudinal ligament was extensive or coincident with ossification of the intraspinal ligament, however, the results were not as predictable.

Classification and treatment of axis body fractures

We have classified 31 cases of axis body fracture by the type of bony injury depicted in radiographic images into the following four types: avulsion, transverse, burst, and sagittal fractures. The results of treatment in these types were retrospectively analyzed. In all of nine cases of avulsion fracture and two cases of transverse fracture, bone union was obtained by nonoperative treatment. All three cases of burst fracture healed, one by nonoperative treatment, and the remaining two by C2/3 anterior interbody fusion. Bone union was also obtained in all of the 17 cases of sagittal fracture, which included nonoperative treatment in 15 cases, and transoral atlanto-axial fusion in the remaining two cases. because many axis body fractures are inherently stable injuries, the authors normally select nonoperative treatment as initial therapy. However, in sagittal fractures, eight patients had sequelae of nuchal pain caused by osteoarthrosis of the atlanto-axial joint. As a result of these findings, the authors deem it appropriate to utilize atlanto-axial fusion when severe malalignment of the atlanto-axial joint is recognized.

Multiple regression analysis of the factors influencing the results of expansive open-door laminoplasty for cervical myelopathy due to ossification of the posterior longitudinal ligament.

Abstract We conducted a multiple regression analysis on the surgical results (minimum follow-up of 5 years) of 55 patients who underwent expansive open-door laminoplasty (open-door ELAP) for cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL) in order to determine statistically the impact of factors influencing the results. Duration of myelopathy was found to be a significant factor indicating poor results, while progression of ossification and age at the time of surgery were significant factors indicating deterioration. Three other factors (preoperative severity of myelopathy, degree of spinal canal expansion and changes of the curve indices before and after surgery) did not have a significant influence on the results. To improve the surgical results, it is thus essential to operate on patients as soon as they develop symptoms of myelopathy. There exists a certain limitation in posterior decompression for OPLL including open-door ELAP until prevention of the progression of ossification becomes possible.

Dorsal shift and expansion of the spinal cord after expansive open-door laminoplasty

We investigated dorsal shift and anteroposterior spinal cord diameter after expansive open-door laminoplasty, comparing pre- and postoperative computed tomographic myelographic images to clarify the relationships between surgical outcome and these changes. Dorsal shift occurred at the midcervical spine in cervical spondylotic myelopathy (CSM) but was less extensive in ossification of the posterior longitudinal ligament (OPLL). Spinal cord anteroposterior diameter expanded for OPLL but did not for CSM. Correlation of outcome and dorsal shift was not significant for OPLL or CSM. Correlation of outcome and expansion was significant for OPLL, but not for CSM.

Myelopathy secondary to ossification of the posterior longitudinal ligament of the thoracic spine treated by anterior decompression and bony fusion

We examined the utility of anterior decompression and bony fusion via the extrapleural approach in the treatment of thoracic myelopathy secondary to ossification of the posterior longitudinal ligament (OPLL). Patient outcome and complications were analyzed in 48 patients treated with this procedure, with a follow-up of at least 2 years. The Japanese Orthopaedic Association score was used to evaluate the severity of the thoracic myelopathy, and the recovery rate was used to evaluate the surgical outcome. The outcome, postoperative complications, radiographic evaluations of bony union, and progression of OPLL within the area of anterior decompression were examined. The T3 vertebral body was the highest level to which anterior decompression was applied. The average follow-up period was 57 months with a recovery rate of 56.7% which stabilized 1 year after operation. However, the surgical outcome was less favorable in patients with long-standing myelopathy, extensive OPLL, or thoracic OPLL with coexisting intraspinal ligament ossification. Four patients experienced deterioration of their myelopathy, and seven patients had the postoperative complication of extraspinal leakage of cerebrospinal fluid. The myelopathy was transient in all but one patient. Radiographic studies showed that bony union was achieved and restenosis of the spinal canal due to progression of OPLL within the area of decompression did not occur. We conclude that anterior decompression and bony fusion using the extrapleural approach provides a good outcome and is useful in treating mid- and lower thoracic OPLL when performed carefully at an early stage of disease.

Prognosis of neurological deficits associated with upper cervical spine injuries

We investigated the type of injury and neurological prognosis in 82 patients with an upper cervical spine injury with neurological deficits, from a total of 247 such patients that we treated, from which 11 patients who were dead on arrival had been excluded. The incidence of neurological deficits in upper cervical spine injury was 33%. They were classified into three signs; cord, upper cervical nerve root, and cranial nerve signs. The types of injury accompanied by neurological deficits were burst fracture of the atlas, type II dens fracture, body fracture of the axis, type II traumatic spondylolisthesis of the axis, atlanto—occipital dislocation, and atlanto-axial dislocation. Most were unstable vertebral injuries. The four patients who died after arrival at hospital had complete tetraplegia with respiratory distress. The neurological deficit was one of paresis in the 78 patients who survived; in many, the paresis was mild with a resulting good neurological prognosis.