Idiopathic chronic hypertrophic pachymeningitis causing thoracic cord compression.

Chronic idiopathic pachymeningitis is a rare cause of compressive myelopathy, especially of the thoracic spinal cord. The hypertrophic dura causes symptoms either by pressure on the spinal cord or by vascular compromise. The authors report the diagnostic dilemmas in a 48-year-old lady who presented with progressive spastic paraparesis of 4 months duration. MRI showed an extradural hypointense band, surrounding and flattening the thoracic cord in the anteroposterior direction, extending from C7 to T11. Neither the CT scan nor the myelogram provided any clue to the diagnosis. A T1-T10 laminectomy was performed. The dura was hypertrophied and found compressing the cord. The posterior dura was excised and the spinal cord was decompressed. The histopathology showed hypertrophic pachymeningitis. The patient improved neurologically. She was started empirically on anti-tubercular chemotherapy, though she was serologically negative for all known causes of pachymeningitis.