Supplementary motor area syndrome after surgery for parasagittal meningiomas

Resection within the supplementary motor area (SMA) may be accompanied by dramatic motor deficits and speech arrest when the dominant hemisphere is involved, termed the SMA syndrome. Typically, the muscle tone of the paralyzed extremities is preserved, and in most cases, a complete or near complete recovery is seen within a few months. The SMA syndrome has not been recognized for extra-axial tumor surgery in approximation of the SMA.

We observed the SMA syndrome in a patient operated for a parasagittal meningioma in the posterior frontal region, and this observation intrigued us to prospectively collect similar cases.

In the period from January 2010 to December 2015, we observed five patients who developed a partial SMA syndrome after surgery for frontal parasagittal meningiomas. The muscle tone was preserved in the affected extremities. All patients experienced improvement in motor function within a few days, and on follow-up, three out of five patients had recovered completely. Three of the patients had meningioma WHO grade II.

Surgically induced SMA syndrome can easily be confused with pyramidal weakness. This series of cases demonstrate that the syndrome may also develop after removal of extra-axial tumors and is probably underdiagnosed and underreported. The good functional prognosis is helpful in the preoperative counseling and follow-up of these patients.