Recovery of corticospinal tract injured by traumatic axonal injury at the subcortical white matter: a case report

The corticospinal tract (CST) is a major neural tract for motor function in the human brain. In addition, CST is mainly concerned with execution of movement of the hand (Jang, 2014). However, few studies are reported on the mechanism underlying CST recovery after traumatic brain injury (Seo and Jang, 2015). In this study, we report on a case that showed recovery of an injured CST by traumatic axonal injury (TAI) at subcortical white matter, as detected on follow up diffusion tensor tractography (DTT). A 54-year-old male patient who had suffered head trauma after being hit by a bus at a crosswalk as a pedestrian underwent conservative management for an intracerebral hema-toma in the right frontotemporal lobes at the department of neurosurgery in a university hospital (Figure 1A). The patient lost consciousness for approximately 30 minutes and experienced post-traumatic amnesia for 2 weeks from the time of the accident. He was transferred to the rehabilitation department of another university hospital for rehabilitation at 2 weeks after onset. Although he presented with quadripa-resis, the left finger extensor showed more severe weakness than the right finger extensor (Medical Research Council [right/left]: 4/3; 0: no contraction, 1: palpable contraction, but no visible movement, 2: movement without gravity, 3: movement against gravity, 4: movement against a resistance lower than the resistance overcome by the healthy side, 5: movement against a resistance equal to the maximum resistance overcome by the healthy side) (Council, 1976). The grip strength of the hands was evaluated using a dyna-mometer (Kim et al., 1994). The average scores across three trials were 17/13 kg [right/left]. The Purdue pegboard scores which were the average peg counts across three trials during 30 seconds, were 6/4 [right/left] (Kim et al., 1994). Higher score indicates much stronger muscle strength or hand function in all tests. For about 9.5 months from 2 weeks to 11 months after onset, the patient underwent comprehensive rehabilitative management in the university hospital and a local rehabilitation hospital. Until 11 months after onset, quadriparesis had improved to a nearly normal state as follows: in particular, the left weakness was more improved than the right weakness: finger extensors (Medical Research Council: 5/5), the grip strength of the hands was 34/30 kg, and the Purdue pegboard scores were 14/13. Diffusion tensor imaging (DTI) data were acquired twice (2 weeks, and 11 months after onset) using a 6-channel head coil on a 1.5 T Philips …