The diagnostic value of multimodal intraoperative monitoring (MIOM) during spine surgery: a prospective study of 1,017 patients.

A prospective study of 1,017 patients who received MIOM during spine surgery procedures between March 2000 and December 2005. To determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve roots function during spine surgery. MIOM has become a widely used method of monitoring neural function during spine surgery. Several techniques only monitor either ascending or descending pathways and thus may not provide sensitive or specific results. MIOM aims to monitor both ascending and descending pathways therefore giving immediate feedback information regarding any neurological deficits during the operation. Intraoperative sensory spinal and cortical evoked potentials, combined with monitoring of EMG and motor evoked potentials recorded from the spinal cord and muscles elicited by electrical motor cortex, spinal cord, cauda equina and nerve root stimulation, was evaluated and compared with post-operative clinical neurological changes. One thousand and seventeen consecutive patients underwent a total of 4,731 h of MIOM to evaluate any neural deficits that may have occurred during spine surgery. Of these, 935 were true negative cases, 8 were false negative cases, 66 were true positive cases and 8 were false positive cases, resulting in a sensitivity of 89% and a specificity of 99%. Based on the results of this study, MIOM is an effective method of monitoring the spinal cord functional integrity during spine surgery and therefore can lead to reduction of neurological deficit and consequently improve postoperative results.

The validity of multimodal intraoperative monitoring (MIOM) in surgery of 109 spine and spinal cord tumors.

In a prospective study of 109 patients with tumor of the spine MIOM was performed during the surgical procedure between March 2000 and December 2005. To determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve root function during surgical procedure of spinal tumors. MIOM become an integrated procedure during surgical approach to intramedullar and extramedullar spine tumors. The combination of monitoring ascending and descending pathways may provide more sensitive and specific results than SEP alone giving immediate feedback information regarding any neurological deficit during the operation. Intraoperative sensory spinal and cerebral evoked potential combined with EMG recordings and motor evoked potential of the spinal cord and muscles were evaluated and compared with postoperative clinical neurological changes. One hundred and nine consecutive patients with spinal tumors of different aetiologies were monitored by the means of MIOM during the entire surgical procedure. Eighty-two patients presented true negative findings while two patients monitored false negative, one false positive and 24 patients true positive findings where neurological deficits after the operation were present. All patients with neurological deficit recovered completely or to pre-existing neurological situation. The sensitivity of MIOM applied during surgery of spinal tumors has been calculated of 92% and specificity 99%. Based upon the results of the study MIOM is an effective method of monitoring the spinal cord and nerve root function during surgical approach of spinal tumors and consequently can reduce or prevent the occurrence of postoperative neurological deficit.

Computer-navigated pedicle screw insertion in the lumbar spine.

OBJECTIVE: Decrease of surgical risks in transpedicular, lumbar spondylodesis by insertion of screws into the pedicle under continuous visual control of the screw channel in the sagittal, axial, and orthogonal planes in relation to the direction of screw insertion. INDICATIONS: All indications of a transpedicular lumbar spondylodesis performed for intervertebral instability, spinal stenosis, or displacement of vertebrae secondary to degenerative diseases. CONTRAINDICATIONS: Previous surgery that does not permit the obligatory intraoperative matching. Usual contraindications for lumbar spondylodesis. Spondylolyses, as they rarely allow a satisfactory result of matching due to the mobility in the vertebral segment. SURGICAL TECHNIQUE: Preoperative multi-slice computed tomography (CT). Intraoperative matching of real and virtual views. On the monitor the instruments are controlled visually in their relation to the lumbar spine in almost real time. Opening of pedicles and insertion of screws. Only thereafter, treatment of the pathologic conditions either by decompression or realignment of the spine. RESULTS: Between July 2000 and February 2002 this system was selected for 109 patients. No complications were observed and no revision became necessary. The screw length varied between 35 and 50 mm; the length of the screws does not affect the procedure. Intra- and postoperative radiographs (anteroposterior and lateral) were done in every patient. The first 48 patients underwent CT control that confirmed the optimal intrapedicular and intravertebral screw position. Thereafter, these controls were omitted for cost-saving.

Pseudocystic degeneration of the lumbar ligamentum flavum: a little known entity.

OBJECTIVE: The objective of this work was to investigate the clinical and histologic features of patients with pseudocystic lesions of the ligamentum flavum in the lumbar region of the spinal canal and ascertain the existence of genuine ligamentum flavum pseudocysts. METHODS: Retrospective chart and histologic study of a patient cohort with lumbar radiculopathy due to a cystic intraspinal lesion and who had undergone decompressive surgery was conducted. Intraoperatively, the stenosing process had been found to be different from common etiologic entities and had been submitted for histologic examination. RESULTS: The 33 patients with symptoms and signs of lumbar radiculopathy were between 48 and 85 years of age (mean 63.5 years). Twenty (61%) of them were women. All patients showed degenerative changes of the bony structures of the spine by conventional radiography. Segmental instability due to degeneration of the lumbar spine was present in 45%. Computed tomography and/or magnetic resonance imaging showed a cystic lesion. Clinical and histologic examination confirmed their origin from within the severely degenerated ligamentum flavum. CONCLUSIONS: Radiologic, surgical, and histologic findings suggest that the pseudocystic degeneration of the ligamentum flavum represents a genuine entity that is associated with degenerative changes of the structures of the respective lumbar spine segment. These pseudocystic lesions may compress the adjacent nerve roots, provoking symptoms and signs of radiculopathy. The findings suggest that the surgical treatment not only must consist of removal of the pseudocyst but must also include a radical extirpation of the ligamentum flavum surrounding the pseudocyst to avoid recurrence of such a lesion.