Congenital Mirror Movements in a New Italian Family

Abstract

Mirror movements (MMs) occur on the contralateral side of a limb being used intentionally. Because few families with congenital MMs and no other neurological signs have been reported, the underlying mechanisms of MMs are still not entirely clear. We report on the clinical, genetic, neurophysiological and neuroimaging findings of 10 of 26 living members of a novel four‐generation family with congenital MMs. DCC and RAD51 were sequenced in affected members of the family. Five of the ten subjects with MMs underwent neurophysiological and neuroimaging evaluations. The neurophysiological evaluation consisted of electromyographic (EMG) mirror recordings, investigations of corticospinal excitability, and analysis of interhemispheric inhibition using transcranial magnetic stimulation techniques. The neuroimaging evaluation included functional MRI during finger movements. Eight (all females) of the ten members examined presented MMs of varying degrees at the clinical assessment. Transmission of MMs appears to have occurred according to an autosomal‐dominant fashion with variable expression. No mutation in DCC or RAD51 was identified. EMG mirror activity was higher in MM subjects than in healthy controls. Short‐latency interhemispheric inhibition was reduced in MM subjects. Ipsilateral motor‐evoked potentials were detectable in the most severe case. The neuroimaging evaluation did not disclose any significant abnormalities in MM subjects. The variability of the clinical features of this family, and the lack of known genetic abnormalities, suggests that MMs are heterogeneous disorders. The pathophysiological mechanisms of MMs include abnormalities of transcallosal inhibition and corticospinal decussation.

The impact of brain lesion characteristics and the corticospinal tract wiring on mirror movements in unilateral cerebral palsy

“…These children could have a simultaneous activation of both primary motor cortices (M1) that could elicit MM due to insufficient interhemispheric inhibition. This mechanism has been shown to be the source of MM in typically developing children 4 and in adults with congenital MM 22 . Interestingly, lesion location was not retained in the model as a factor related to MM similarity, suggesting that the cortical location of the lesion might not be that relevant.…”

Functional Magnetic Imaging in a Case of Congenital Mirror Movement

“…Diffusion tensor imaging or functional MRI has recently come to the fore as neuroimaging to evaluate mirror movements. Changes in the corpus callosum volume, reduction in transcallosal motor fibers, and bilateral motor cortex activation can be seen in functional MRIs (1). We also think that when such complaints are encountered, functional MRI should primarily be kept in mind and preferred to show the etiopathology non-invasively, in a better and shorter time and to assist in the distinction between acquired and congenital forms.…”

“…Mirror movements are involuntary movements caused by synchronised mimicry of one side's voluntary muscle movements by opposite limb's homologous muscles. Mirror movements can be seen in all limbs but are mostly seen in the upper limbs, especially in hands (1,2). It is normal to see mirror movements among children before the age of 10 because myelination of corpus callosum has not been finished.…”

“…Acquired mirror movements can be seen with many neurodegenerative diseases such as Parkinson's disease and Corticobasal syndrome. Can also accompany stroke, cervicomedullary junction lesions, essential tremor, dystonia, and amyotrophic lateral sclerosis (1,2,4,7,8).…”

Tremor with congenital mirror movements: evidence of involvement of the primary motor cortex in tremor

“…It remains inconclusive whether centrally generated tremor oscillation travels via the primary motor cortex (M1) through corticospinal tracts [1]. Here we report two subjects with congenital mirror movements (CMMs) [2] who developed two different types of tremor.…”