Coexistence of Myotonic Dystrophy and Normal Pressure Hydrocephaly: Causative or Incidental?

Abstract

OBJECTIVE: Myotonic dystrophy type 1 (DM1) is the most common adult muscular dystrophy involving not only the striated muscle but also multiple systems including central nervous system, resulting from an autosomal dominantly inherited gene mutation causing trinucleotid repeats. Neuroimaging findings in patients with DM1 are ventricular enlargement, hyperintensity of white matter at the posterior-superior trigone (HWMPST), hyperostosis frontalis interna and thining of corpus callosum. Although ventriculomegaly is reportedly the most common finding, DM1 in association with normal pressure hydrocephalus (NPH) has been reported in anecdotal case reports. The aim of the study is investigate the frequency of ventriculomegaly and also clinical diagnosis of NPH in patients with DM1 in a retrospective case series.

METHODS: Neuroimaging (mostly cranial MRI) findings in 20 patients (9 women; mean age: 38,25 years ± 10,26[range: 18-60]; mean disease duration: 18,9 years ± 10,5 [5-43]) with DM1 diagnosed with clinical and electromyographic findings are examined retrospectively.

RESULTS: The available neuroimaging data came from MRI scans in 19 cases and CT scans in the remaining case. Ventriculomegaly as decided by increased ventriculocerebral index (VCI) was evident in only two patients who were siblings, one of whom also had classical NPH clinical triad. After ventriculoperitoneal shunt his urinary incontinence and gait difficulty had improved.

CONCLUSION: This retropective analysis did not support the view that the ventriculomegaly is a frequent neuroimaging finding in adult DM1. A prospective study, preferably with genetic data that would also allow the correlation of the number of trinucleotid repeats with the abnormal neuroimaging findings, might better answer the question whether ventriculomegaly is causally associated with adult DM1, and NPH could be its secondary clinical presentation, thus further complicating the late course of this already disabling disease, since that latter condition is reversable when recognized early.

Keywords: Myotonic dystophy Type 1, neuroimaging, ventriculomegaly, normal pressure hydrocephaly