Abstract
BackgroundIdiopathic Normal Pressure Hydrocephalus (iNPH) can be effectively treated through shunt insertion. However, most shunted patients experience little or no clinical benefit, which suggests suboptimal patient selection. While contentious, multiple studies have reported poorer shunt outcomes associated with concomitant Alzheimer’s disease. Prompted by this observation, multiple studies have assessed the role of amyloid PET, a specific test for Alzheimer’s disease, in patient selection for shunting. MethodsA comprehensive literature search was performed to identify studies that assessed the association between amyloid PET result and the clinical response to shunting in patients with suspected iNPH. Pooled diagnostic statistics were calculated. ResultsAcross three relevant studies, a total of 38 patients with suspected iNPH underwent amyloid PET imaging and shunt insertion. Twenty-three patients had a positive clinical response to shunting. 18/28 (64.3%) of patients with a negative amyloid PET and 5/10 (50%) with a positive amyloid PET had a positive response to shunting. The pooled sensitivity, specificity and accuracy was 33.3%, 76.2% and 58.3%. None of these statistics reached statistical significance. ConclusionThe results of this pooled analysis do not support the selection of patients with suspected iNPH for shunting on the basis of amyloid PET alone. However, due to small cohort sizes and weakness in study design, further high-quality studies are required to properly determine the role of amyloid PET in assessing this complex patient group.
Highlights
Idiopathic normal pressure hydrocephalus is a communicating hydrocephalus that causes a progressive syndrome typified by cognitive impairment, gait apraxia and urinary incontinence [1]
We present a pooled analysis of three non-randomised studies that have examined the association between amyloid PET and the clinical response to shunt insertion
The main finding in this pooled analysis is that amyloid PET, when considered in isolation, does not accurately identify patients with suspected Idiopathic Normal Pressure Hydrocephalus (iNPH) who are likely to respond to shunting
Summary
Idiopathic normal pressure hydrocephalus (iNPH) is a communicating hydrocephalus that causes a progressive syndrome typified by cognitive impairment, gait apraxia and urinary incontinence [1]. Develops despite normal CSF opening pressure on lumbar puncture. Disruption of normal CSF dynamics [2, 3], ciliary dysfunction [4], accumulation of toxic metabolites [5], reduced glymphatic drainage [6], and impaired cerebrovascular autoregulation [7], have all been implicated, but the pathogenesis of iNPH remains poorly understood. Haemorrhage, infection, over-drainage, obstruction and device failure occurs in 38% of patients [8, 9]. Permanent neurological sequalae or death occurs in 6% of patients [10]
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