Motor recovery by the aberrant pyramidal pathway in a patient with cerebral infarct

The aberrant pyramidal tract (APT) refers to the collateral pathway of the pyramidal tract (PT) descending through the medial lemniscus in the midbrain and pons. We report on a patient who showed changes of the APT from the early stage to the chronic stage concurrent with motor recovery following an infarct in the cerebral peduncle.

An 84-year-old female patient presented with moderate motor weakness of her upper and lower extremities (2/2) due to cerebral infarct on the right cerebral peduncle of midbrain. One week after her stroke, her motor weakness was similar to that at the onset (2/2). During 5 weeks' rehabilitation, her motor weakness recovered to the point that she was able to move upper and lower extremities against gravity with some resistance (4/4).

Cerebral infarct on the right cerebral peduncle of midbrain INTERVENTIONS:: She participated in a comprehensive rehabilitative management program, including movement therapy, neurotrophic drugs, and neuromuscular electrical stimulation therapy of the left finger extensor and ankle dorsiflexor muscles.

On 1-week and 6-week diffusion tensor tractographys (DTTs), the right PT was not reconstructed, but the right APT, which descended through the medial lemniscus pathway at the midbrain and pons and the pyramid at the medulla, was observed. The right APT became thicker on six-week DTT compared with 1-week DTT. On 1-week transcranial magnetic stimulation study, an motor evoked potential with delayed latency and decreased amplitude was evoked from the affected (right) hemisphere (latency: 24.4 msec and amplitude: 0.2uV). In contrast, its latency was decreased and amplitude was increased on six-week transcranial magnetic stimulation study (latency: 21.8 msec, amplitude: 0.8 uV) CONCLUSIONS:: We demonstrated changes in the APT from the early stage to the chronic stage concurrent with motor recovery in a patient with an infarct in the cerebral peduncle. Our findings have important implications that a spared APT could contribute to the motor recovery in patients with cerebral infarct when the PTis completely injured at the onset of cerebral infarct,.