Motor nervous system impairment persists in long-term survivors of childhood acute lymphoblastic leukemia.

Background: The objective of the current study was to determine whether therapy for childhood acute lymphoblastic leukemia (ALL) results in long-lasting neurologic signs or electrophysiologic injuries within the motor tracts.

Methods: Twenty-seven children who were treated for ALL were studied clinically 5 years after the cessation of therapy by means of motor-evoked potentials (MEPs) elicited by magnetic stimulation transcranially and peripherally. An equal number of healthy children matched with regard to age, gender, and height served as the control group.

Results: The MEP latencies to the hands and legs elicited by stimulation at the cortex were prolonged significantly in the children treated for ALL compared with the control group, with the differences being 2.2 milliseconds [ms] (P < 0.001) from the cortex to the thenar on the right side and 2.0 ms (P < 0.001) on the left, and 1.4 ms (P = 0.004) from the cortex to the leg on the right side and 1.3 ms (P = 0.004) on the left. Correspondingly, the MEP latency from the fifth lumbar vertebrae (LV) level to the leg also was prolonged, by 1.0 ms (P = 0.005) on the right side and 0.8 ms (P = 0.005) on the left side. The calculated latency between the cortex and the LV level was not found to be significantly longer in those patients treated for ALL compared with the healthy controls. Neurologic signs, in the form of depressed deep tendon reflexes, were observed in 8% of the patients, whereas approximately 33% of the patients were found to have fine or gross motor difficulties and dysdiadochokinesia.

Conclusions: Neurologic signs still persisted 5 years after therapy for ALL. Approximately 33% of the patients had fine or gross motor difficulties and dysdiadochokinesia, and demyelinative injuries to the peripheral nerve tracts were found proximally but not within the central nervous system.