Normal-Pressure Hydrocephalus-Like Appearance in Myotonic Dystrophy Type 1

Area of Science:

• Neurology
• Medical Imaging

Background:

• Myotonic dystrophy type 1 (DM1) is a common monogenic neurological disorder.
• Normal pressure hydrocephalus (NPH) is prevalent in the elderly, sharing symptoms like gait disturbance, incontinence, and cognitive decline with DM1.

Observation:

• A 54-year-old man with DM1 presented with symptoms and brain imaging (enlarged ventricles, Evans index 0.38) mimicking NPH.
• Two tap tests (TT) were performed; the first showed slight improvement, while the second was unremarkable.

Findings:

• The patient's clinical presentation and imaging findings suggested NPH, but the second tap test result precluded an NPH diagnosis.
• Brain imaging in DM1 patients over 50 can resemble NPH.

Implications:

• Tap test results for NPH diagnosis require cautious interpretation, especially in DM1 patients.
• Multiple tap tests may be necessary to accurately diagnose NPH and prevent unnecessary surgical interventions in DM1 patients.