Electrophysiologic deterioration in surgery for thoracic disc herniation

Th. Disc Herniation

Eur Spine J (2014) 23:2279–2290

Severe thoracic disc herniation leads to increased pressure in adjacent neural structures, which in turn can require an increase in mean arterial pressure (MAP) to maintain adequate spinal cord perfusion.We report a case series of three patients with severe thoracic disc herniation that experienced deteriorations in motorevoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) following induction of general anesthesia, but prior to decompression of the neural elements.

Methods In-depth chart reviews were completed for each patient from their initial presentation to long-term postoperative course. Careful attention was taken with regards to MAP at induction of each operative case.

Results The origin of the decreased signals in all patients was thought to relate to inadequate cord perfusion pressures. Two of the patients recovered pre-operative neurologic function while the third was left with mild postoperative paraparesis. Mean arterial pressures at time of deterioration were noted to be 58, 80, and 60 mmHg. These measurements represented MAPs approximately 65, 92, and 60 % those of baseline values, respectively.

Conclusion Based on these experiences, the authors’ institution has adopted new guidelines in the setting of thoracic disc herniations that includes pre-operative optimization of volume status, placement of an awake arterial line prior to induction of anesthesia, use of MEP and SSEP electrophysiologic monitoring, careful selection of anesthetic, and aggressive maintenance of MAPs >110 % of preoperative values at all times prior to decompression of the spinal cord.

Thoracoscopic Resection of Symptomatic Herniated Thoracic Discs

Spine 2012 ; 37 : 35 – 40

Study Design. Retrospective review of a prospectively maintained surgical database.

Objective. To report the indications, surgical procedures performed, and outcomes from the largest series of thoracoscopically treated herniated thoracic discs (HTDs). We also compared approach-related complications with an unmatched cohort undergoing thoracotomy for HTD.

Summary of Background Data. Symptomatic HTDs are rare, and their surgical management is technically challenging.

Methods. A prospectively maintained surgical database of all patients undergoing surgery for symptomatic HTDs by the senior author (blinded for review) was reviewed. As needed, the database was supplemented with hospital and clinic charts and telephone conversations with patients. A triportal method of thoracoscopic discectomy was performed in all cases.

Results. Between 1994 and 2008, 121 patients underwent 125 thoracoscopic-assisted operations for 139 HTDs. Their mean age at surgery was 46.6 years. Indications for thoracoscopic resection currently include small symptomatic disc, anterior location, nonmorbidly obese patient, favorable chest anatomy, and T4–T11 location. Symptom duration averaged 32 months. Radiculopathy was the most common presentation, followed by myelopathy and pain (radiculopathic or back). The mean hospital stay was 4.8 days. Chest tubes remained in place for a mean of 3.2 days. At a mean follow-up of 2.4 years, myelopathy, radiculopathy, and back pain had resolved or improved at a rate of 91.1%, 97.6%, and 86.5%,of cases, respectively. Most patients (97.4%) would be willing to undergo the operation again. The complication rate was acceptable. Patients undergoing thoracoscopic excision had less approachrelated morbidity than an unmatched cohort undergoing excision using thoracotomy.

Conclusion. Thoracoscopic-assisted microsurgical resection is a safe, effective, and minimally invasive method of treating symptomatic HTDs in appropriately selected patients. The symptoms of most patients improve or resolve with minimal morbidity.