Spinal deformity surgery carries the risk of neurological injury. Neurophysiological monitoring allows early identification of intraoperative cord injury which enables early intervention resulting in a better prognosis. Although multimodal monitoring is the ideal, resource constraints make surgeon-directed intraoperative transcranial motor evoked potential (TcMEP) monitoring a useful compromise. Our experience using surgeon-directed TcMEP is presented in terms of viability, safety, and efficacy. We carried out a retrospective review of a single surgeon’s prospectively maintained database of cases in which TcMEP monitoring had been used between 2010 and 2017. The upper limbs were used as the control. A true alert was recorded when there was a 50% or more loss of amplitude from the lower limbs with maintained upper limb signals. Patients with true alerts were identified and their case history analyzed.Aims
Methods
The aim of this study was to evaluate the feasibility
of using the intact S1 nerve root as a donor nerve to repair an avulsion
of the contralateral lumbosacral plexus. Two cohorts of patients
were recruited. In cohort 1, the L4–S4 nerve roots of 15 patients
with a unilateral fracture of the sacrum and sacral nerve injury
were stimulated during surgery to establish the precise functional
distribution of the S1 nerve root and its proportional contribution
to individual muscles. In cohort 2, the contralateral uninjured
S1 nerve root of six patients with a unilateral lumbosacral plexus
avulsion was transected extradurally and used with a 25 cm segment
of the common peroneal nerve from the injured leg to reconstruct
the avulsed plexus. The results from cohort 1 showed that the innervation of S1 in
each muscle can be compensated for by L4, L5, S2 and S3. Numbness
in the toes and a reduction in strength were found after surgery
in cohort 2, but these symptoms gradually disappeared and strength
recovered. The results of electrophysiological studies of the donor
limb were generally normal. Severing the S1 nerve root does not appear to damage the healthy
limb as far as clinical assessment and electrophysiological testing
can determine. Consequently, the S1 nerve can be considered to be
a suitable donor nerve for reconstruction of an avulsed contralateral
lumbosacral plexus. Cite this article:
