Spinal Cord Monitoring in Patients with SMA Type III: A Case Report

Introduction: We report results from spinal cord monitoring (SCM) of a paraparetic patient suffering from spinal muscular atrophy type IIIa.

Case Report: A 13.1-year-old female patient who was suffering from SMA type IIIa underwent spinal deformity surgery due to neurogene scoliosis (Cobb angle 56 degrees) because of recurrent pulmonary infections and persistent back pain.

SMA type IIIa was diagnosed by molecular genetic testing and muscular biopsy.

Spinal cord monitoring with motor (MEP) and sensory-evoked potentials (SEP) were performed.

Method: The MEP was induced by transcranial electrical stimulation of the motor cortex applying five electric impulses of 100 mA and 0.2 Hz. We performed MEP in M. tibialis anterior, M. hallucis longus, and M. abductor pollicis brevis in both the sides as well as SEPs by stimulation of N. medianus and N. tibialis.

In advance, nerve conduction velocity (NCV) of N. peroneus com. was tested.

Results: Preoperatively, NCV offered reproductive potentials.

During surgery, our patient showed regular MEP with physiological latencies and amplitudes. SEP findings were normal as would be expected.

Discussion: The case report shows that the SCM with MEP in patients with advanced cases of SMA type IIIa is profitable, if stimulation of peripheral nerves offer regular potentials.

Using repetitive stimulation, we found reproducible MEP because of the greater corticomotoneuronal projection for spinal motoneurons to survive. The repetitive stimulus of the motor cortex activates motoneurons in a more synchronous matter, whereby we found the detectable motoric response in patients with advanced disease pattern.

Conclusion: Spinal cord monitoring with MEP and SEP can be gainfully performed in patients with SMA.

Keywords: spinal cord monitoring, SMA IIIa.