Case of Idiopathic Spinal Cord Herniation, a Rare Underrecognized Cause of Myelopathy Presenting as Brown-Séquard Syndrome
Objective:
To educate neurologists about a rare and often missed cause of progressive myelopathy.
Background:
The first published case of idiopathic spinal cord herniation (ISCH) was in 1974 [1]. Nearly all published cases of ISCH are ventral herniation of the spinal cord though a dural defect in the thoracic spine with the most common presenting neurological signs and symptoms being Brown-Séquard Syndrome (BSS) [2,3]. In one of the largest published case series of 34 patients, the mean time from symptom onset to diagnosis was 4.4 +/- 3.9 years [2]. Earlier diagnosis is important since surgery is usually effective in halting the progression of myelopathy [3].
Results:
A 61-year-old man presented for a second opinion with approximately 4 years of progressive symptoms of left leg burning pain, right leg weakness with tingling, and constipation. Two years prior, the patient underwent lumbar spine surgery x 2 without improvement. At time of presentation to our center, his neurological exam showed findings of BSS with sensory level at T5. Initial thoracic spine MRI was read as unremarkable, but on review and on updated MRI showed anterior deviation and flattening of the ventral spinal cord at T2-3 (image 1). CT myelogram showed focal ventral cord herniation at T2-T3 in the right paramedian region (image 2).
Conclusions:
This case illustrates a rare underrecognized cause of progressive thoracic myelopathy with delay in diagnosis of approximately 4 years, that presented as BSS. Though thoracic spine MRI often shows findings suggestive of spinal cord herniation, this finding can be subtle and initially missed, as in this patient. Cases are also missed due to inadequate neurological exam which at time of diagnosis most commonly shows BSS. This patient successfully underwent laminectomy with decompression of spinal cord and repair of anterior dural defect at T3 which was successful in halting the progression of myelopathy.
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