The Predictive Value of Conductance to Outflow of CSF in Normal Pressure Hydrocephalus

Abstract

Conductance to outflow of CSF was measured in a prospective study of 80 patients with normal pressure hydrocephalus. Measured outflow was compared with clinical findings, computed tomography, intracranial pressure measurements and with the results of shunting. Follow-up time was one year. Outflow measurements predicted the outcome of shunting in 96 per cent of the patients. Patients with the combination of known aetiology, short history, gait disturbances, severe dementia, urinary incontinence and hydrocephalus on CT can be shunted without further investigations. Periventricular hypodensity on CT scanning predicts an excellent result for shunting. Based on results of preoperative investigations and outcome of shunting we propose a programme for the investigation of future patients with normal pressure hydrocephalus.

Should ventriculoatrial shunting be the procedure of choice for normal-pressure hydrocephalus?

“…[14][15][16]22,29,34 Likewise, the complication and mortality rates were somewhat lower, although largely consistent with previously published findings in series where VA and VP shunt complications were not directly compared. The infection rates in our VP and VA shunt cohorts were lower than those seen in other reports, which range from 2.5% to 18.9% 4,12,20,21,23,31,35 and from 0% to 13%, 3,5,13,19,20,30 respectively. Similarly, mortality rates for VP shunt and VA shunt surgery have been documented at 0%-6% 4,11,12,21,35 and 0%-9%, 3,12,15,20,25,34 respectively-rates that are consistent with the present study.…”

Idiopathic normal pressure hydrocephalus may be a “Two Hit” disease: Benign external hydrocephalus in infancy followed by deep white matter ischemia in late adulthood

“…Given the apparent benignancy, none of these children ever get a saline infusion test (requiring a lumbar puncture), which would continue to demonstrate decreased CSF resorption. Only 60 to 80 years later, when they are being evaluated for a gait disturbance, dementia, and possible NPH, will they have a saline infusion test, showing decreased CSF resorption (23,24). That histologic analysis of the meninges in NPH fails to show evidence of SAH or meningitis (25) is supportive of this theory.…”

Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus: Second Edition

“…The efficacy of shunt procedures maintained for the short term ranged from 3-6 months in 64-96% of patients, 2,5,15,21,22,24,32,35,36,48) and at 1 year in 41-95% 10,12,18,25,33,40,49,50,62,66) ; while the efficacy of shunt procedures maintained for the long term ranged from 3-5 years in 28-91% of patients. 2,9,21,32,36,38,46,49,50,52) The best improvement rate was for gait disturbance, between 58-90%.…”

“…Reduced venous circulation in the sagittal and straight sinuses and intracranial compliance on heart rate-gated phase-contrast MRI have been reported, 11,12) but their diagnostic values have not been established.…”