[Usefulness of transcranial magnetic stimulation in the objective assessment of therapy for adrenoleukodystrophy]

Adrenoleukodystrophy (ALD) is a hitherto untreatable, X-linked recessive disorder of the central nervous system characterized by the systemic accumulation of very-long-chain fatty acids. Although various treatments have been proposed, objective evidence of their efficacy is insufficient. This is partly due to the absence of an appropriate method for evaluating the functions of the central nervous system (CNS). In this study, we took up the central motor conduction time (CMCT) as an index of the CNS functions, and measured it in two patients with ALD under steroid pulse therapy to know if this parameter is useful in assessing the effects of therapy. The right and the left motor cortex was stimulated separately with a MAGSTIM 200 magnetic stimulator, using a round coil of 9cm mean diameter to stimulate the hand area or a double cone coil to stimulate the leg area. CMCT, the time an impulse takes to travel from the motor cortex to the anterior horn cells in the corresponding region, was measured by a combination of transcranial magnetic stimulation (TMS) and F wave technique. Before treatment, CMCT to the cervical cord was prolonged slightly in both patients; CMCT to the lumbar cord was prolonged slightly in one and moderately in the other. After repeated steroid pulse therapy, a definite improvement, although partial and transient, was observed in either case. TMS thus seems to be useful not only for detecting functional derangement of the pyramidal tract but for evaluating the efficacy of therapy for this disease.