Richard E. Lindseth

Factors related to false- versus true-positive neuromonitoring changes in adolescent idiopathic scoliosis surgery

Study Design. A retrospective study of 134 adolescent patients who underwent surgical correction of idiopathic scoliosis between June 1992 and August 1998 was conducted. Objective. To examine factors related to changes in somatosensory-evoked potentials with or without neurogenic motor-evoked potentials. Summary of Background Data. Studies document and demonstrate threshold criteria for changes in neuromonitoring that predict changes in spinal cord function. Rates of false-negative occurrences are low, yet higher rates of false-positive findings may result. Methods. All the patients had somatosensory monitoring, and 71 patients had both somatosensory-evoked potential and neurogenic motor-evoked potential monitoring. Gender, age, curve types, duration of surgery, type and amount of instrumentation, and amount of correction were examined for their effects on monitoring. Estimated blood volume loss as well as high and low mean arterial pressure and its variance were assessed at the start, middle, and conclusion of the procedure. Results. According to the findings, 122 patients (91%) had no monitoring changes and no postoperative neurologic deficit. Six patients (4.5%) had false-positive readings. Six patients had a postoperative motor or sensory deficit, all of which resolved within 18 months. False-positive readings were associated with greater variability in mean arterial pressure. No consistent predictions could be made about the incidence of cord injury if neuromonitoring changes returned to baseline before the end of surgery. Conclusions. Questions remain about the predictive accuracy of somatosensory-evoked and neurogenic motor-evoked potentials. According to the findings in this study, in which there were no false-negative readings and a modest false-positive rate, continued use of these methods is recommended. Higher false-positive rates were seen in patients with greater lability in mean arterial pressure. A wake-up test is recommended for all cases in which threshold monitoring changes occur because cases of spinal cord injury may exist even when monitored variables return to baseline.

Myelodysplasia and Developmental Scoliosis: A Manifestation of Syringomyelia

Fourteen of 15 myelodysplastic patients evaluated for developmental scoliosis were found to have communicating hydrosyringomyelia, a manifestation of spontaneously arrested hydrocephalus. Eight of these patients had progressive extremity paralysis in addition to the scoliosis. Treatment by ventricular decompression was associated with short term stabilization in 6 early cases of scoliosis. However, more advanced scoliosis in 2 patients continued to progress. Neurologic deficits were improved even in advanced cases by ventricular shunting. The authors propose that hydromyelia and syringomyelia are the cause of developmental scoliosis in myelodysplasia and suggest methods of investigating and treating patients with these conditions.

Meningomyelocele and Syringohydromyelia

Twenty meningomyelocele patients with nonfunctional ventricular shunts or no shunts were studied radiologically. This group was compared to a second group of 4 patients with functional shunts. The various techniques are compared and discussed. Pantopaque ventriculography is a potentially dangerous procedure. Radioisotope ventriculography appears to be a safe and useful method of diagnosing syringohydromyelia. Ventricular decomposition by means of a shunt appears to be an effective treatment.

Alterations in Cerebrospinal Fluid Dynamics in Syringomyelia, Hydromyelia, and Myelomeningocele

Syringomyelia is a relatively uncommon disease of cystic cavitation of the spinal cord, generally found at the cervical and thoracic levels. Characteristically, the syringomyelic cyst lies separate from the spinal central canal, as distinct from hydromyelia, in which the central canal is distended with cerebrospinal fluid (CSF). However, the two conditions may coexist and may be difficult to distinguish histologically.24 Furthermore, some investigators, noting that syringomyelia and hydromyelia may share a common etiology, have substituted the term syringohydromyelia.3

Polypropylene Lower-Extremity Braces for Paraplegia Due to Myelomeningocele

Because our experience with the conventional steel brace on children paralyzed by myelomingocele was generally unsatisfactory, we developed a polypropylene solid-ankle orthosis, using the principles of the SACH prosthesis and gait mechanics. This brace was applied to forty-seven children with paralysis at the third to fifth lumbar level, forty-three of whom showed considerable improvement in their gait. Reduced bracing was possible in eighteen patients. The over-all patient acceptance of the brace was due to improved appearance and comfort, increased stability, and improved gait. From our experience we feel that this is a major advancement in the bracing of children who are partially paralyzed at the third lumbar level or below.

Fractures in Children

Fractures in children differ in many ways from fractures in adults and often require a different approach to treatment. These differences, and their impact on the management of pediatric fractures, are discussed and principles of treatment are reviewed.

Moire Topography For The Detection Of Orthopaedic Defects

Moire topography is applied for the follow-up of scoliosis patients. The results are then compared with the X-rays. A special lamp and scale arrangement is utilized for patient alignment. It is suggested that this technique will be used for the detection of all orthopaedic defects.