Unusual presentation of spinal cord compression related to misplaced pedicle screws in thoracic scoliosis

Abstract

Utilization of thoracic pedicle screws is controversial, especially in the treatment of scoliosis. We present a case of a 15-year-old girl seen 6 months after her initial surgery for scoliosis done elsewhere. She complained of persistent epigastric pain, tremor of the right foot at rest, and abnormal feelings in her legs. Clinical examination revealed mild weakness in the right lower extremity, a loss of thermoalgic discrimination, and a forward imbalance. A CT scan revealed at T8 and T10 that the right pedicle screws were misplaced by 4 mm in the spinal canal. At the time of the revision surgery the somatosensory evoked potentials (SSEP) returned to normal after screw removal. The clinical symptoms resolved 1 month after the revision. The authors conclude that after pedicle instrumentation at the thoracic level a spinal cord compression should be looked for in case of subtle neurologic findings such as persistent abdominal pain, mild lower extremity weakness, tremor at rest, thermoalgic discrimination loss, or unexplained imbalance.

Adolescent idiopathic thoracic scoliosis: apical correction with specialized pedicle hooks

“…Both reported excellent correction using such techniques (72% of Cobb angle correction for Suk and 59% for Liljenqvist). However, this can only be used in experienced hands and the possible neurologic complications due to a misplaced pedicle screw must be kept in mind [20]. The small size, the rotation and the surgical anatomy of the pedicle at the thoracic level in AIS makes the insertion of pedicle screws even more difficult.…”

“…Their superior correction could be explained by the rigid fixation achieved with pedicle fixation and the number of vertebrae instrumented. However, neurologic concern still remains with the use of pedicle screws [20]. Specialized pedicle hooks (SPH), where the pedicle hooks are augmented with 3.2-mm fixation screws were devised as an alternative to pedicle screws in the thoracic spine (Fig.…”

Segmental pedicle screw instrumentation in idiopathic thoracolumbar and lumbar scoliosis

“…In thoracic scoliosis, Suk et al demonstrated a shorter fusion length and a better three-dimensional correction with posterior pedicle screw instrumentation compared to hooks [39]. However, both neural and vascular, as well as visceral, structures are at potential risk from misplaced pedicle screws [6,10,16,35,[40][41][42]. In order to evaluate frontal and sagittal plane correction in thoracolumbar and lumbar scoliosis by use of segmental pedicle screw instrumentation, with special regard to fusion length and accuracy of pedicle screw placement, a prospective clinical trial was conducted.…”

CT Provides Precise Size Assessment of Implanted Titanium Alloy Pedicle Screws

“…Several studies have been devoted to developing safe techniques for screw placement [3,5,8,9], whereas others focus on anatomic structures at risk during screw placement [5, 7, 12, 16, 19-22, 29, 30, 32, 33]. Although rare, neurologic injury as a result of malpositioned pedicle screws has been reported [4,6,18,23]. When postoperative neurologic changes occur, it is vital that the surgeon have a reliable method to image the spine to look for iatrogenic injury.…”

“…However, use of pedicle screws involves some risk, especially if the pedicle wall is violated or the screw tip extends anywhere outside the vertebral body. Numerous authors reported misplaced screws with resultant nerve root compression, impingement on vascular structures, or spinal cord injury [4,6,13,23]. In situations where postoperative imaging is required to assess implant position, several options exist, including plain radiography, CT, and MRI.…”