Various pathologic findings provided important foundations for discussing the pathogenesis of lesions in ligamentum flavum. Calcification was frequently observed in elderly patients and those with cauda equina symptoms, and these patients tended to have severer preoperative symptoms. Chondroid cells were frequently observed in patients with spondylolisthesis, and patients with ossification had a greater % slip, suggesting involvement of mechanical load in ossification of ligaments. The pathologic findings were significantly related to the clinical features, and these findings will be profitable for understanding the pathogenesis of degenerative lumbar disease.

The ligamentum flavum is considered to be one of the important causes of radiculopathy in lumbar degenerative disease. Although there have been several reports anatomically examining the positional relationship between the ligamentum flavum and nerve root, there are few reports on ventral observation. The purpose of this study is to clarify the shape of the ligamentum flavum seen ventrally, and to obtain anatomic findings related to nerve root compression. The subjects were 18 adult embalmed cadavers, with an average age of 78 years at the time of death. The ventral shapes of the ligamentum flavum were observed. The relationships between the morphological change of the ligamentum flavum and nerve root compression or radiographic findings were statistically evaluated. Among the shapes of the ligamentum flavum, bulging of the ligament was most frequently observed. Proximal bulging indicates the type with the cranial portion bulging from the subarticular zone to the foraminal zone of the ligamentum flavum. In this type associated with a decrease in disc height, nerve root compression was frequently observed. Thus, we could more realistically grasp the relationship between bulging morphology of the ligamentum flavum and nerve root compression.

IntroductionReid [43,44] and Breig and colleagues [3,4], on the basis of a cadaveric study, hypothesized that spinal cord compression by the vertebral bodies and intervertebral discs during neck flexion caused cervical myelopathy. Later, the pincer mechanism of the cervical spine became emphasised, and neck extension was thought to be the predominant pathology of cervical myelopathy [41]. HowAbstract Previous studies have suggested that spinal cord compression by the vertebral bodies and intervertebral discs during neck flexion cause cervical flexion myelopathy (CFM). However, the exact pathophysiology of CFM is still unknown, and surgical treatment for CFM remains controversial. We examined retrospectively patients with CFM based on studies of the clinical features, neuroradiological findings, and neurophysiological assessments. The objectives of this paper are to investigate the pathophysiology of CFM, and to examine an optimal surgical treatment. Twenty-three patients (20 male, three female) with age of onset ranging from 11 to 23 years (mean 15.7 years) were examined for the study. All patients were inspected by magnetic resonance imaging (MRI), myelogram, or computed tomographic myelogram (CTM) of the cervical spine. In eight patients, dynamic motor evoked potentials (MEP) studies were performed. Five patients underwent surgical treatment; two patients had cervical duraplasty with laminoplasty, two patients had musculotendinous transfer, one patient had both of these procedures, and the remaining 18 patients were treated conservatively. Amyotrophy of the hand intrinsic and flexor muscle group of the forearm except the brachioradial muscle was observed hemilaterally in 20 patients and bilaterally in three patients. In three patients, T1-weighted MRI with neck flexion showed linear high intensity regions in the epidural space. In all patients, axial MRI/CTM demonstrated flattening of the spinal cord with the posterior surface of the dura mater shifting anteriorly. The amplitude of MEPs decreased after cervical flexion in two patients with progressive muscular atrophy. In three patients, dysesthesia of the upper extremities disappeared following cervical duraplasty. Musculotendinous transfer for three patients significantly improved the performance of their upper extremity. The findings of this study suggest that degenerative changes of the dura mater may be a characteristic pathology of CFM. Cervical duraplasty with laminoplasty is effective for cases at an early stage, and musculotendinous transfer should be selected in patients at a late stage.

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