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Practice Easily missed?

Idiopathic normal pressure hydrocephalus

BMJ 2016; 354 doi: (Published 17 August 2016) Cite this as: BMJ 2016;354:i3974
  1. Aravindhan Baheerathan, core medical trainee1,
  2. Devkishan Chauhan, core medical trainee2,
  3. Louis Koizia, specialist registrar in care of the elderly3,
  4. Hugh O’Neal, care of the elderly consultant4
  1. 1Department of Neurology, University College Hospital, London WC1E 6AG, UK
  2. 2Department of Medicine, Kingston Hospital, Kingston-Upon-Thames KT2 7QB, UK
  3. 3Department of Medicine, Northwick Park Hospital, Harrow HA1 3UJ, UK
  4. 4Care of the Elderly Department, Worthing Hospital, Worthing BN11 2DH, UK
  1. Correspondence to: A Baheerathan a.baheerathan89{at}

What you need to know

  • Consider the diagnosis in patients with progressive gait, balance, or cognitive problems, and/or urinary incontinence over three months

  • Refer to neurology for exclusion of alternative diagnoses and neuroimaging. Ventriculomegaly in the absence of substantial sulcal atrophy is typical on neuroimaging

  • Shunt surgery is the mainstay of treatment and improves symptoms, though long term data are lacking. Around 1 in 10 patients may experience complications of subdural haematoma, seizures, intracerebral haemorrhage, and infection in the postoperative period

A 74 year old man describes problems with his balance and walking for a year. His family say he is increasingly forgetful, and he has had urinary incontinence recently. He is referred to neurology, where a computed tomography (CT) scan of the brain reveals ventriculomegaly in the absence of substantial sulcal atrophy, consistent with normal pressure hydrocephalus.

What is idiopathic normal pressure hydrocephalus?

A triad of gait and balance impairment, cognitive impairment, and urinary incontinence characterise idiopathic normal pressure hydrocephalus. The symptoms progress insidiously over at least three months. There is ventriculomegaly without marked elevation in cerebrospinal fluid pressure. Normal pressure hydrocephalus may be secondary to alternative pathologies, for example, subarachnoid haemorrhage, meningitis, or traumatic brain injury.1 The pathogenesis of idiopathic normal pressure hydrocephalus has been widely debated but no single theory has gained widespread acceptance.

How common is idiopathic normal pressure hydrocephalus?

  • Evidence on the epidemiology of idiopathic normal pressure hydrocephalus is poor. Prevalence and incidence statistics are inaccurate and variable1 …

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