[Cervical myelopathy due to hypertrophy of the posterior longitudinal ligament (HPLL)--a case report].

: We reported a case of cervical myelopathy due to hypertrophy of the posterior longitudinal ligament (HPLL). A 56-year-old man who developed spastic gait and urinary disturbance was admitted to our hospital. Neurological examination disclosed muscle weakness and hyperreflexia in all extremities, and superficial sensory disturbance below Th 4. Neither plain films nor tomograms of the neck showed ossification of the posterior longitudinal ligament (OPLL). However, myelography, myelo-CT and MR scan revealed HPLL and anterior compression of the cervical cord at C2-C6. From these findings, we diagnosed this case as cervical myelopathy due to HPLL. Clinical symptoms were relieved by posterior decompressive laminoplasty. HPLL has been preserved. During the following four years, ossification has not emerged into the hypertrophic region of posterior longitudinal ligament. This case suggests that HPLL may be a novel clinical category of compression myelopathy. Further observation will be needed.