Diagnosis and management of idiopathic normal-pressure hydrocephalus

Abstract

The diagnosis and management of idiopathic normal-pressure hydrocephalus (iNPH), a disorder of gait impairment, incontinence, and dementia that affects elderly patients, incorporates an organized approach using familiar principles for neurologists. The starting point is a comprehensive history and neurologic examination, review of neuroimaging, and evaluation of the differential diagnosis. Coexisting disorders should be treated before specific iNPH testing is performed. Specific iNPH testing includes assessing patient response to temporary CSF removal and testing CSF hydrodynamics. In properly selected patients, all iNPH symptoms, including dementia, can improve after shunt surgery. The longitudinal care of iNPH patients with shunts includes evaluation of the differential diagnosis of worsening iNPH symptoms and treatment of coexisting disorders. Evaluation of shunt obstruction is often indicated, and if it is found, surgical correction is likely to result in symptomatic improvement.

Figure. MRI of a 73-year-old woman with impairment of gait and balance, bladder control, and cognition for 3 years

The patient had not improved with treatment for parkinsonism. A trial of CSF removal via external lumbar drainage produced substantial gait improvement, and she was treated with a ventriculoperitoneal shunt. At baseline, the Tinetti score was 12–16/28, which is significantly impaired; 9 months after shunt surgery, the score was 26/28, and the patient walked effortlessly. (A) Axial T2 imaging consistent with the Japanese “high and tight” criteria for the convexity. The interhemispheric fissure is effaced. (B) Axial T1 imaging shows a widened IIIrd ventricle with a span of 10 mm. (C) Sagittal T1 imaging shows bowing of the corpus callosum and a pulsation artifact (flow void) in the Sylvian aqueduct. (D) Axial fluid-attenuated inversion recovery imaging shows measurement of the Evans ratio. The diameter of the frontal horns is 4.4 cm, the widest brain diameter is 13.7 cm, and the Evans ratio is 0.32.