[The clinical features of cervical spondylosis with boule musculaire].

To clarify the pathophysiology of boule musculaire associated with cervical spondylosis, we investigated the 13 patients (11 males and 2 females) with cervical radiculopathy caused by cervical spondylosis. None of the patients had any subjective symptoms such as sensory disturbance, weakness in the boule musculaire, and muscle atrophy of the insurround region near the boule musculaire. Among 21 tendon reflexes of the biceps muscle of the arm, 9 were normal, 8 were decreased and 4 were increased. Among the 13 patients there was only 2 clinical cases of cervical myelopathy. MRI obtained from 3 patients demonstrated a compressed cervical cord. Electromyography obtained from 7 patients demonstrated mild neurogenic changes such as polyphasic or prolonged motor unit potential (MUP) in the boule musculaire and in the atrophic regions. However, there was no giant MUP, fasciculation, fibrillation, nor positive sharp waves suggesting denervating lesions below the anterior horn in any patient. It was considered that the boule musculaire observed in cervical spondylosis gradually developed from a relatively mild disturbance of the ventral root. Moreover, the boule musculaire developed more often in the male patients, and predominantly on the right side. Cervical spondylosis accompanying boule musculaire may be a prodromal stage or a mild type of cervical spondylotic amyotrophy.