Neurological involvement in 51 cystinosis patients: A single-center experience

Cystinosis is a lysosomal storage disease resulting from impaired transport of cystine due to variants in CTNS gene. Cystine accumulation leads to renal, corneal, and endocrine involvements. Patients typically present with growth retardation, polyuria/polydipsia, rickets. However, neurological manifestations are rare and become more pronounced with increasing age.

Fifty-one patients with cystinosis were evaluated using cerebral magnetic resonance imaging, electroneuromyography, audiological and psychometric tests.

The mean age of the patients was 164.8 ± 112.4 months. The common symptoms were failure to thrive (56.9 %), polyuria/polydipsia (45.1 %), and short stature (37.3 %). Renal, endocrine, ocular, and neurological involvement was present in 100 %, 78.4 %, 76.5 %, and 49 % of patients, respectively. Abnormal magnetic resonance imaging findings were observed in three patients. Psychometric tests were performed in 20 patients. Four patients had borderline intelligence, two had mild, four had moderate, and two had severe intellectual disability. Eight patients had delays in personal-social, fine/gross motor, and language development. Two of 29 patients who underwent audiological evaluation were found to have hearing loss. Three patients had neuropathy, one had myopathy. One patient had epilepsy. There was no significant difference in cystine levels between the patients with and without neurological involvement.

Compared to literature, our study appears to be a case series in which mental affect was reported the most. This effect may be due to frequent hospitalization, lack of stimulation, sociocultural status of the family and cortical atrophy in patients with chronic renal disease. Hearing loss was first reported in our study, regardless of audiotoxic drug usage.