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Cerebral reorganization of language and motor control secondary to chronic hemispheric vasculopathy in a patient with homozygous sickle‐cell disease

A 43-year-old man with homozygous sickle-cell disease (SCD) had a first ischemic stroke in the left middle cerebral artery territory at the age of 15 years, with a minor persistent neurological deficit of right limbs due to occlusion of the left middle cerebral artery with a Moya-Moya-like lenticular-striatal collateral network. At 32 years, he had a second left hemisphere stroke, involving the whole territory of the middle and posterior cerebral arteries, sparing only prefrontal areas. This second major infarct produced only limited clinical symptoms: incomplete right hemiparesis and hypoesthesia, right lateral hemianopia, and reduced verbal fluency without overt aphasia. Morphological magnetic resonance imaging (MRI) showed atrophy of the left cerebral hemisphere and peduncle associated with Wallerian degeneration. Single-photon-emission computed tomography (SPECT) showed hypoperfusion of the entire left cerebral hemisphere. In contrast, no vasculopathy was revealed by magnetic resonance angiography (MRA), SPECT, or transcranial doppler ultrasonography of the right cerebral hemisphere. Functional mapping of the motor cortex was obtained with trans-cranial magnetic stimulation (TMS) with MRI-guided navigation [1]. Navigated TMS showed that all motor-evoked potentials recorded on the right side of the body had their origin in the right precentral cortex. In addition, functional MRI showed that language functions had been lateralized in the right hemisphere (Image 1). This unusual lateralization of motor and language functions in the right hemisphere suggests successful adaptive neuroplasticity from the damaged left hemisphere to the right Image 1. A–C: axial slices and 3D reformat of SPECT showing hypoperfusion of the whole left hemisphere, sparing the right side. D-E: three language functions assessed by fMRI: verbal fluency (in red), categorical fluency (in orange) and semantic association (in pink). 3D reconstruction of the left (D) and right (E) hemispheres co-registered with language responses show that language functions are absent in the left hemisphere, but largely present in the right frontal inferior and opercular area. F-I: Functional mapping of the motor cortex using transcranial magnetic stimulation and the Eximia NBS System (Nexstim, Helsinki, Finland). Markers colored grey show stimulus locations evoking no motor response (F, H), while markers colored pink or red show stimulus locations producing motor evoked potentials >50 mV in amplitude (G, I): the darker the color, the larger the response. This mapping shows that motor responses on the right side of the body had their cortical origin only in the right hemisphere.