SMA is a degenerative motor neuron disease causing paralysis of varying occurrence and intensity. It is classified into four types, type I, of early onset in infants being the largest group.
In the last few years, innovative therapies arrived on the market including nusinersen (or Spinraza®), a product based on antisense oligonucleotides. A few cases of hydrocephalus have been reported following intrathecal injections of nusinersen.
In an article published in May 2021, the Biogen laboratory, which develops nusinersen, reports the results of a study, conducted by itself and intended to establish the prevalence of this cerebral anomaly both in patients with SMA and in a control population of the same age. The authors analyzed an anonymized health database of 100 million people in the United States over a period of ten years (early 2007 to late 2016, therefore before the availability of nusinersen). Thus, 5354 cases of SMA were identified and compared to a matched control population. The incidence of hydrocephalus, although very low (15.5 cases per 100,000), was four times higher than that found in the control population (incidence of 4.7 per 100,000). The results of this study would be such as to exclude nusinersen in the occurrence of such a complication.