Progressive Myelopathy After Spine Surgery

A 69-year-old man with a progressive myelopathy for 2 years was referred for evaluation of suspected transverse myelitis. His medical history included discectomies, a severe episode of herpes simplex virus type 1 meningoencephalitis, and development of insidiously progressive numbness and weakness of his hands. Cervical spine magnetic resonance imaging showed 2 small, dural-based, gadolinium-enhancing lesions. Biopsy of these lesions showed only normal neural tissue. Subsequently, the dura was stripped away surgically from the lower cervical region, in an effort to remove these lesions. During the next year, a sensory level developed at about the level of the nipples (T4), along with a squeezing sensation on his trunk below. Imbalance and bilateral lower extremity weakness and numbness then developed. Magnetic resonance imaging showed a longitudinally extensive cord signal abnormality. The cause of the patient’s initial subjective hand numbness and weakness was indeterminate. The onset of severely progressive symptoms after surgical removal of those lesions and the reported stripping of dura made it likely that the progressive cord edema was due to chronic adhesive arachnoiditis. His prior meningoencephalitis was a potential additional risk factor for arachnoiditis. Computed tomography myelography showed a markedly abnormal spinal canal with scalloping of the cord contour, with delayed flow of contrast above C6-C7, consistent with arachnoid adhesions causing obstruction of normal cerebrospinal fluid flow. The patient was diagnosed with chronic adhesive arachnoiditis. A C4-C7 laminectomy and surgical lysis of the cord meningeal adhesions was performed, with subsequent intensive neurorehabilitation. Follow-up spinal cord magnetic resonance imaging 6 months after surgery showed improvement of the T2-signal abnormality but persistent myelomalacia and spinal cord atrophy. Adhesive arachnoiditis is an uncommon cause of progressive myelopathy resulting from an insult to the arachnoid meningeal layer, followed by inflammation and fibrosis. This process renders the arachnoid abnormally thick and adherent to the pia and dura mater. Abnormal adhesion of nerve roots or spinal cord to the dura produces neurologic impairment. Typical symptoms include back pain, paresthesias, lower limb weakness, and sensory loss. It is diagnosed clinically with supportive magnetic resonance imaging and computed tomography myelography findings.