Mucopolysaccharidosis type IVA: evidence of primary and secondary central nervous system involvement

Abstract

Mucopolysaccharidosis type IVA is a rare lysosomal storage disease caused by a deficiency of N-acetylgalactosamine 6-sulfatase. Studies usually focus on skeletal abnormalities and their consequences. This study explores the neurological manifestations in a cohort of mucopolysaccharidosis type IVA patients, with a detailed focus on brain and spinal magnetic resonance imaging (MRI) findings. We performed a cross-sectional study involving nine patients with a biochemical confirmation of mucopolysaccharidosis type IVA. The protocol consists of a comprehensive clinical examination and brain and spinal cord MRI analysis for all subjects. The mean age was 16.4 years (±5.7) and the mean onset of symptoms was 11.5 months (±6.3). Overall, cognition was spared in all but one patient and motor weakness was a constant finding in all patients. Deep sensation impairment was found in six patients. The brain MRIs showed non-specific white matter changes in two patients. Other abnormalities such as clival hypoplasia, basilar invagination, and arachnoid cists appeared in seven of the nine patients. Eight patients presented spinal cord compression, and in three of them, two spinal levels were compromised. Odontoid hypoplasia and degenerative features in the neuroaxis were present in all patients. Our experience with mucopolysaccharidosis type IVA patients supports the evidence of central nervous system involvement. We emphasize the importance of regular clinical assessments with complete MRI studies, as an attempt to detect the early signs of spinal cord compression. This evaluation may be especially important before surgical interventions, as occult lesions may become symptomatic and promote postoperative unfavorable outcomes.

Keywords: atlantoaxial subluxation; brain white matter; central nervous system; cervical; mucopolysaccharidosis type IVA.