A 13-year-old female child complained of back pain, weakness in the left lower extremity and difficulty in walking. At that time, she had scoliosis from T5 to T10 and her kyphotic angle was 65.4°. She was advised to wear Milwaukee brace. During a follow up visit (9 months later), her complaints of back pain had become more pronounced and difficulty in walking had aggravated. Radiologic examination revealed curve progression despite the presence of brace. At this time, the kyphotic angle had increased to 69.5°. The computerised tomography (CT) scan revealed a kyphoscoliotic spine with T7 hemivertebra (). Her paraparesis had worsened and the neurologic examination revealed some weakness in the ankle dorsilfexors of both the sides (left > right). Knee jerk was exaggerated on both the sides. Sensations were preserved in both the lower limbs. She had a left sided spastic gait and had difficulty in balancing while walking. The MRI revealed a flattened cord with signal changes over the apex of kyphotic deformity with T7 hemivertebra (). In the wake of these developments, she was advised a deformity correction surgery along with anterior decompression to which the parents of the child agreed to.
Fig. 1 Preoperaive computed tomography scan (A) showing 3D reconstrution of whole spine wherein kyphotic deformity at T7 hemivertebra can be visualized. The T2 weighted magnetic resonance imaging (B, C) shows an overstretched flattened cord with signal changes (more ...)
A surgical protocol in the form of posterior correction of the kyphoscoliotic curve with instrumentation (monoaxial pedicle screw system), posterior decompression, posterior to anterior excision of T7 hemivertebra, spondylodesis and anterior interbody fusion was planned for her. After facetectomy from T3 to T10, posterior instrumentation was done from T3 to T10 sparing T7. The instrumentation was followed by posterior decompression by partial hemilaminectomy T6 and bilateral total laminectomy T7. While carrying out the T7 hemivertebra excision, a trans cranial electrical motor evoke potential evaluation was carried out and it showed a near 100% drop in both the lower extremities (). Following the condition, the surgery was stopped, and a calculated dose of methyl prednisolone was administered intravenously and a wake up test was called for. Wake up test elicited weak (less than grade 5) movements of both the ankles and great toes. In the wake of a weakly positive wake up test, the surgery was not finished to its conclusion. The hemivertebra excision was discontinued and the deformity was fixed in situ with short rods (T5, T6, and T8) without further correction of the deformity or anterior interbody fusion ().
The trans cranial electrical motor evoke potential recordings while carrying out excision of hemivertebra reveal a significant drop to 6 µV on left side and to 7 µV on right side.
Fig. 3 Immediate postoperative radiograph (A) shows a T3 to T10 instrumented spine with short rods with incomplete excision of T7 hemivertebra. Postoperative computed tomography scan (B-D) on first postoperative day confirms a partially excised T7 hemivertebra (more ...)
Patient was shifted to intensive care unit, where the steroid therapy was continued besides routine supportive medication. On first postoperative day, CT scan revealed an incompletely decompressed T7 hemivertebra with its posterior cortex intact and kyphotic deformity persisting (). Thereafter, a gradual decline in the neurologic status was observed. On second postoperative day, power in all the muscle groups of right lower extremity was grade 4 and in that of left lower extremity was grade 3. On the third postoperative day, power decreased to grade 2 in right lower extremity and grade 1 in the left lower extremity. On MRI, a flattened spinal cord over the kyphotic deformity along with signal changes and a localized hematoma posterior to the cord were observed (). The neurologic deterioration continued and neurology became grade 0 in all the groups of muscles (both lower extremities) on fourth postoperative day. An exploratory surgery was performed and the minimal hematoma was drained. Contrary to the MRI findings, the hematoma was not found compressing the cord. Yet in the following period, there was no improvement in the neurologic status. Three weeks later, the short rods were replaced with proper length rods (from T3-T10) and anterior column reconstruction and interbody fusion (T6-T8) with titanium mesh cage and auto lamina bone graft were carried out (). Thereafter, the patient was discharged and she reported to our branch hospital for rehabilitation and physiotherapy.
The final surgery carried out three weeks later, wherein short rods were removed and proper sized rods along with anterior interbody fusion T6-7-8 with titanium mesh cage and auto lamina bone graft were implanted.