Infantile neuroaxonal dystrophy - Clinical spectrum and diagnostic criteria

Objective: To present clinical, neurophysiologic, and neuroradiologic findi ngs in 13 patients with infantile neuroaxonal dystrophy (INAD), focusing on aspects that assist early diagnosis. Background: Clinicopathologic diagnos tic criteria for INAD were delineated by Aicardi and Castelein in 1979, but atypical cases are reported frequently and little is known of the diagnost ic utility of MRI. Methods: The authors reviewed the clinical, neurophysiol ogic, and MRI findings of 13 patients who met the diagnostic criteria for I NAD. Results: Symptoms onset was between 6 months and 2 years of age. In ni ne patients the clinical course was typical, with rapid motor and mental de terioration; in four patients progression was slower and the clinical pictu re was different. Electromyographic (EMG) signs of chronic denervation, fas t rhythms on EEG and abnormal visual evoked potentials were observed in all patients during the disease course. Cerebellar atrophy with signal hyperin tensity in the cerebellar cortex on T2-weighted images were the most charac teristic MRI findings; hypointensity in the pallida and substantia nigra wa s also observed in two patients. alpha-N-acetyl-galactosaminidase activity on leukocytes was normal in the 10 patients tested. Conclusions: EMG and MR I abnormalities are the earliest and most suggestive signs of INAD, which h as a clinical and radiologic spectrum that is broader than reported previou sly.