Complete monoplegia due to limb-kinetic apraxia in a patient with traumatic brain injury

Rationale: Limb-kinetic apraxia (LKA) is a disorder of movement execution that is a result of injury to the corticofugal tracts (CFTs) from the secondary motor area. We report on a patient with traumatic brain injury (TBI) and complete monoplegia due to LKA, which was mainly ascribed to injury of the CFT from the secondary motor area using diffusion tensor tractography. Patient concerns: A 35-year-old male was struck by a car from the side during riding an autocycle and received direct head trauma as a result of falling to ground. He lost consciousness for approximately 1 month and experienced continuous post-traumatic amnesia after the accident. The patient's Glasgow Coma Scale score was 3 and he showed quadriparesis including complete monoplegia of his left arm since the onset of TBI. Diagnoses: The patient diagnosed complete monoplegia due to LKA after traumatic brain injury. Interventions: He underwent conservative management for TBI followed by rehabilitation at approximately 2 months after onset. Outcomes: At 32-month after onset, weakness on left arm (Manual Muscle Test [MMT]:0) and partial weakness of left leg (MMT:3). Outcomes: Results of electromyography and nerve conduction studies of left extremities were normal. Motor evoked potential values obtained from the abductor pollicis brevis muscle (APB) were: right APB latency 22.3msec, amplitude 1.6mV; left APB latency 22.8msec, amplitude 1.5mV. After 2 weeks of administration of dopaminergic drugs for improvement of LKA, left arm weakness had recovered to level that permitted movement against gravity (MMT:3). Diffusion tensor tractography at 32-month after onset showed right corticospinal tract discontinuation at the pontine level and partial tearing of the left corticospinal tract at the subcortical white matter. In addition, the left CFT from the supplementary motor area showed partial tearing at the subcortical white matter. Lessons: The LKA due to injury of the left supplementary motor area-CFT was demonstrated in a patient with complete monoplegia following TBI. Accurate diagnosis of LKA is important for successful rehabilitation because LKA is known to respond to dopaminergic drug treatment.