An 82-year-old man presented with a 10-day history of progressive bilateral lower limb weakness and generalized numbness in his thorax and lower limbs. He reported a 3-week history of worsening gait ataxia, on a background history of 5 years of mild gait disturbance. On admission, the patient denied having problems with defecation, but had acute difficulty with micturition which resulted in catheter insertion. There was no history of spinal surgery, trauma, or spinal disorders. His medical history included ischemic heart disease, stroke, prostate cancer, and Paget's disease. Clinical examination was significant for a T4 sensory level, with reduced sensation to pin prick and light touch. Motor assessment revealed reduced power in bilateral lower limbs, with the following MRC grades: 1+/5 proximal and 3/5 distal. MRI was diagnostic for ISCH. T2-weighted images demonstrated ventral displacement of the thoracic spinal cord with moderate flattening, focal atrophy, and anterior herniation through the dura at T3-5 []. The CSF flow pattern dorsal to the cord at that level was preserved, but ventral to the cord, the CSF flow pattern was absent. Following a full discussion of the options with the patient, the decision was made for non-operative management. At 3 months after presentation, the patient remained neurologically stable.
A 48-year-old female presented with two year history of back pain and progressive difficultly walking. She gradually developed increasing numbness in both lower limbs over one year. She also developed increasing urinary retention. There was no history of trauma/fever or any other systemic disease. She was evaluated by an orthopedic spine surgeon and was referred to a physician following a negative lumbar magnetic resonance imaging (MRI). Neurological examination revealed presence of weakness in bilateral lower extremities (4-/5, Medical Research Council [MRC] grade) and asymmetrical sensory loss from T8 below consistent with a diagnosis of thoracic myelopathy (Nurick grade 4). Persistent symptoms with worsening gait imbalance led us to perform of thoracic spine MRI which surprisingly revealed presence of a focal anterior kink of the thoracic cord at the T7-T8 level (). The spinal cord at T7/8 level was narrow and deformed without any definite T2 signal abnormality with prominence of the dorsal subarachnoid space. The MRI imaging was suspicious of a diagnosis of anterior transdural spinal cord herniation (). Surgical management was planned and a unilateral right paramedian incision was used to perform a transpedicular exposure due to slight eccentric location of the spinal cord herniation to the right (). Intraoperative neuromonitoring was performed recording somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs). T7/T8 pediculotomy was performed with partial costotransversectomy to provide the optimal anterolateral trajectory. A paramedian right dura incision was made, providing exquisite visualization of the anterior dural defect with the herniated spinal cord (). Using a Woodson dissector, the spinal cord was reduced back into the thoracic dura. The SSEP's were normal throughout the procedure. There was transient reduction in MEP amplitude during mobilization of the spinal cord to reduce the herniation. The MEP amplitude returned to baseline status an hour later. A Duragen (Integra Life Sciences Corp., Plainsboro, NJ, USA) patch was used as graft to seal the defect which was reinforced with Tisseel fibrin glue. (Baxter Healthcare Corp., Deerfield, IL, USA) No fusion or instrumentation was performed. Patient experienced improvement in sensory symptoms right after the surgery and had improvement in her pain, motor strength (4+/5, MRC grade) and gait at three months follow-up with improvement in her Nurick myelopathy grade to 2. Postoperative MRI revealed reduction of the spinal cord with no evidence of herniation ().