Normal pressure hydrocephalus: Treatable dementia, missed diagnosis—The Launceston Prevalence Study

Abstract

Normal Pressure Hydrocephalus (NPH) is one of the few treatable forms of dementia, but it is notoriously difficult to diagnose in the elderly. It is often treated by the insertion of ventriculo-peritoneal shunt with significant improvement in the cognitive, gait and urinary functioning. Most studies suggest the condition is rare but there are few studies addressing the prevalence of the condition. We have, therefore, investigated the prevalence of NPH amongst patients with cognitive impairment attending the Memory Disorders Clinic in Launceston. Three hundreds and fifty five consecutive patients were recruited from the Memory Disorders Clinic at the Launceston General Hospital since 2010. The diagnosis of NPH was based on the presence of memory impairment or dementia, and/or balance/gait disorder and the presence of prominent ventricles regardless of cerebral atrophy on MRI of the brain. All patients with NPH were investigated by CSF Flow Study. One hundred and sixty four men and 191 women participated in the study, mean age 73 years (range 32–95 years), mean MMSE score 23 (range 0–30). 190 (54%) patients were diagnosed with mild cognitive impairment, of whom 54 (28%) had underlying anxiety and depression, 23 (12%) had NPH and 9 (5%) had Parkinsonism.165 (46%) were diagnosed with dementia, of whom 77 (47%) had Alzheimer's disease, 33 (20%) had NPH, 20 (12%) had mixed dementia, 9 (5%) had vascular dementia and 26 (16%) were diagnosed with other forms of dementia including Parkinsonism, Lewy Body Disease, Gertsmann Syndrome, and Frontal Lobe Dementia. NPH is probably more common than previously thought. This is important because many patients without shunting might be condemned for years of disabilities and institutionalisation.