It is defined as a temporary paralysis after the resection of brain tumor localized in the SMA. Although in most cases paralysis induced by SMA resection resolves within a short period, the time until complete recovery varies and has not been precisely analyzed to date.
The incidence of transient deficits in the literature after resections of the SMA was up to 89%. Although most authors have described a complete recovery after up to 3 months for motor deficits and up to 8 months for speech disturbance, in all studies concerning motor deficits a low rate of mild but permanent morbidity in terms of disturbed coordination is reported 1) 2) 3).
Clinical symptoms may vary from none to a global akinesia, predominantly on the contralateral side, with preserved muscle strength and mutism. A remarkable feature is that these symptoms completely resolve within weeks to months, leaving only a disturbance in alternating bimanual movements.
In a review Potgieser et al. gave an overview of the old and new insights from the SMA syndrome and extrapolate these findings to seemingly unrelated diseases and symptoms such as Parkinson's disease (PD) and tics. Furthermore, they integrated findings from lesion, stimulation and functional imaging studies to provide insight in the motor function of the SMA 4).
FCMS has many parallels with the much more commonly encountered supplementary motor area syndrome (SMAS). SMAS is characterised by a loss of volitional movement contralateral to the site of injury (usually surgical) in the posterior medial frontal lobe immediately anterior to the primary motor cortex. It is easily recognised clinically by the profound contralateral plegia with maintenance of reflex movements 5).
Data from 20 cases were analyzed. All 20 patients (mean age 54.9 ± 12.6 years) had undergone resection of frontal lobe glioma involving the SMA. The severity of postoperative paralysis was recorded until complete recovery using the Brunnstrom recovery stage index. To investigate factors associated with recovery time, the authors performed multivariate analysis with the following potentially explanatory variables: age, severity of paralysis after the surgery, resected volume of the SMA, and probability of disconnection of fibers running through or near the SMA. Moreover, voxel-based lesion symptom analysis was performed to clarify the resected regions related to prolonged recovery.
In most cases of severe to moderate paralysis, there was substantial improvement within the 1st postoperative week, but 2-9 weeks were required for complete recovery. Significantly delayed recovery from paralysis was associated with resection of the cingulate cortex and its deep regions. The factors found to influence recovery time from paralysis were stage of paralysis at postoperative day 7 and disconnection probability of the cingulum (adjusted R2 = 0.63, p < 0.0001).
Recovery time from paralysis due to SMA syndrome can be predicted by the severity of paralysis at postoperative day 7 and degree of damage to the cingulum 6).
Chivukula et al., evaluated plasticity in speech supplementary motor area (SMA) tissue in two patients using functional magnetic resonance imaging (fMRI), following resection of tumors in or associated with the dominant hemisphere speech SMA. Patient A underwent resection of a anaplastic astrocytoma NOS associated with the left speech SMA, experienced supplementary motor area syndrome related mutism postoperatively, but experienced full recovery 14 months later. FMRI performed 32 months after surgery demonstrated a migration of speech SMA to homologous contralateral hemispheric regional tissue. Patient B underwent resection of a oligodendroglioma NOS in the left speech SMA, and postoperatively experienced speech hesitancy, latency and poor fluency, which gradually resolved over 18 months. FMRI performed at 64 months after surgery showed a reorganization of speech SMA to the contralateral hemisphere. These data support the hypothesis of dynamic, time based plasticity in speech SMA tissue, and may represent a noninvasive neural marker for SMA syndrome recovery 7).
18 consecutive surgeries for gliomas involving the SMA proper performed in 13 patients. Seven cases were recurrence of the tumour. Clinical factors and details of specific resection of the SMA proper (resection of posterior part, medial wall) and cingulate motor area (CMA) were examined.
Eight cases suffered new post-operative neurological deficits. Six of these eight cases had transient deficits. Permanent deficits persisted in two cases with partial weakness or paresis, after rapid improvement of post-operative global weakness or hemiplegia, respectively. The risk of post-operative neurological deficits was not associated with the resection of the posterior part of the SMA proper or the CMA, but was associated with resection of the medial wall of the SMA proper. Surgery for recurrent tumour was associated with post-operative neurological deficits. The medial wall was frequently resected in recurrent cases.
The frequency of post-operative neurological symptoms, including SMA syndrome, may be higher after resection of the medial wall of the SMA proper compared with the resection of only the lateral surface of the SMA proper 8).
Heiferman et al. present two patients who underwent resection of a large parasagittal meningioma in proximity to the SMA-proper in both hemispheres. Following surgery, these patients developed akinetic mutism; the maximal clinical deficit was not immediately evident, but manifested at 48 hours and 1 week respectively. Both patients showed complete recovery of neurological function but the process was slow. Initial return to near normal function was noted at approximately 3 months with a specific pattern; return of strength was first noted in the upper extremities followed by the lower extremities and speech and cognitive function was the last to recover. The unique occurrence of akinetic mutism secondary to bilateral SMA involvement by parasagittal meningiomas of the posterior frontal region is rare. They discuss the clinical and neuropsychological outcomes in these patients along with an analysis of the possible underlying neurophysiological mechanisms of this unique phenomena 9).
Four patients displayed postoperative SMA syndrome on the side of the body contralateral to the SMA resection. All patients developed postoperative severe hemiplegia. One dominant frontal glioma patient was followed by transient mutism and motor aphasia. In this study, there is no correlation between extent of SMA resection and postoperative clinical pattern of deficits 10).
Bannur et al. describe the SMA syndrome in six patients who underwent surgery for tumours located in the SMA, three in the dominant and three in the non-dominant hemispheres. All of them underwent complete resection of the anatomically described SMA, with partial (n = 4) or total resection (n = 2) of the tumour. In the postoperative period, all these patients exhibited reduction of spontaneous movements and difficulty in performing voluntary motor acts to command in the contralateral limbs, although the tone in the limbs was maintained or increased. The function of these limbs in serial automatic motor activities (for example, dressing and walking) was, however, relatively unaffected. Speech deficits were seen in only one of three patients with the dominant SMA syndrome. Besides a severe impairment of volitional movements, the salient features of the deficits in this syndrome are hemineglect and dyspraxia or apraxia involving the contralateral limbs. All patients recovered their motor functions over varying periods of time ranging from one to a few weeks. Long-term follow-up (median 24 months) in five patients revealed complete return of function in the affected limbs. It is important to recognize the entity of the SMA syndrome and differentiate it from the deficits that result from operative damage to the motor cortex as the deficits associated with the former are likely to recover almost completely over a short period of time 11).