Normal Pressure Hydrocephalus (NPH)

Normal pressure hydrocephalus is an increase in pressure within the ventricles of the brain. In NPH, raised CSF pressure causes lower cerebrospinal fluid (CSF) production. Additionally, the aging process also contribiutes to lower CSF production.

normal-pressure-hydrocephalus1

Symptoms:

Urinary incontinence (45-90%)

            – may initially only complain of urgency / frequency

            – rarely may also have fecal incontinence

Mental impairment (up to 80%)

– subcortical-like dementia

– slowing of verbal and motor responses (bradyphrenia)

– apathetic, forgetfulness, decreased attention

– preservation of cortical functions e.g. language

– frontal release signs may be present (snout, glabellar tap, palmomental)

Gait disturbance (up to 90%)

– “apraxic” or “magnetic” gait, inability to life legs as if they are stuck to the floor

– often confused with Parkinsonism(eg vascular) since patient’s may display balance difficulty, shortened stride length, difficulty turning and paratonic rigidity but NPH more broad based, outward rotated feet and diminished height of steps

Causes:

Primary / Idiopathic, disease arising from unknown cause (1/3)

Secondary causes:

           1) Trauma

         2) Infection e.g meningitis

3) Subarachnoid Haemorrhage (SAH)

Bleeding within the head into the space between two membranes that surround the brain.

 The bleeding is beneath the arachnoid membrane and just above the pia mater

       4)     Mucopolysaccharidosis of the meninges

metabolic disorders caused by the absence or malfunctioning of lysosomal enzymes needed to break down molecules called glycosaminoglycans – long chains of sugar carbohydrates in each of our cells that help build bone, cartilage, tendons, corneas, skin and connective tissue.

       5)     Achondroplasia (skeltal disorder causing dwarfism)

Treatment and symptom management:

  • Ventriculoperitoneal shunting

Mayo M, McGuire D, Saul T, Silverberg GD, Rubenstein E. (2003). Alzheimer’s disease, normal-pressure hydrocephalus, and senescent changes in CSF circulatory physiology: a hypothesis. Lancet Neurology. 2(8):506-11.

Neurological Medicine Pocketbook. 2004 Retrived May 1, 2009 from http://www.uwo.ca/cns/resident/pocketbook/disorders/cognitive/nph.htm

Vanneste, J. A. L. (2000) Diagnosis and management of normal-pressure hydrocephalus. Journal of Neurology. 247 (1) 5-14.

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