BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is a type of 
communicating hydrocephalus also known as non-obstructive hydrocephalus. This 
type of hydrocephalus is caused by impaired cerebrospinal fluid reabsorption 
without any obstruction in the ventricular system and is associated with normal 
cerebrospinal fluid pressure. It is characterised clinically by gait 
disturbance, cognitive dysfunction, and urinary incontinence (known as the 
Hakim-Adams triad). The exact cause of iNPH is unknown. It may be managed 
conservatively or treated surgically by inserting a ventriculoperitoneal (VP) or 
ventriculoatrial (VA) shunt. However, a substantial number of patients do not 
respond well to surgical treatment, complication rates are high and there is 
often a need for further surgery. Endoscopic third ventriculostomy (ETV) is an 
alternative surgical intervention. It has been suggested that ETV may lead to 
better outcomes, including fewer complications.
OBJECTIVES: To determine the effectiveness of ETV for treatment of patients with 
iNPH compared to conservative therapy, or shunting of CSF using VP or VA 
shunts.To assess the perioperative and postoperative complication rates in 
patients with iNPH after ETV compared to conservative therapy, VP or VA 
shunting.
SEARCH METHODS: We searched for eligible studies using ALOIS: a comprehensive 
register of dementia studies, The Cochrane Central Register of Controlled Trials 
(CENTRAL) and several bibliographic databases such as MEDLINE (Ovid SP), EMBASE 
(Ovid SP), PsycINFO (Ovid SP), CINAHL (EBSCOhost) and LILACS (BIREME).We also 
searched the Database of Abstracts of Reviews of Effects (DARE) to identify 
potentially relevant reviews. The search strategy was adapted for other 
databases, using the most appropriate controlled vocabulary for each. We did not 
apply any language or time restrictions. The searches were performed in August 
2014.
SELECTION CRITERIA: We included randomised controlled trials (RCTs) of ETV 
treatment of iNPH. Patients had to have at least two symptoms of the Hakim-Adams 
triad. Exclusion criteria were obstructive causes of hydrocephalus, other 
significant intracranial pathology and other confirmed causes of dementia. The 
eligible comparators were conservative treatment or shunting using VP and VA 
shunts.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened search 
results, selected eligible studies, assessed risk of bias and extracted data. We 
contacted trial authors for additional data.
MAIN RESULTS: Only one study met the inclusion criteria: an RCT comparing 
effectiveness of ETV and non-programmable VP shunts in 42 patients with iNPH. 
The study was conducted in Brazil between 2009 and 2012. The overall study risk 
of bias was high. The primary outcome in the study was the proportion of 
patients with improved symptoms one year after surgery, determined as a change 
of at least two points on the Japanese NPH scale. Due to imprecision in the 
results, it was not possible to determine whether there was any difference 
between groups in the proportion of patients who improved 3 or 12 months after 
surgery (3 months: odds ration (OR) 1.12, 95% confidence interval (CI) 0.26 to 
4.76, n = 42; 12 months: OR 2.5, 95% CI 0.62 to 10.11, n = 38). We were unable 
to estimate the effect of treatment on other efficacy outcomes (cognition, 
balance, function, gait and mobility) because they were inadequately reported. 
Of the 26 patients in the VP shunting group, 5 developed subdural hematoma 
postoperatively, while there were no complications among the 16 patients in the 
ETV group (OR 0.12, 95% CI 0.01 to 2.3, n = 42), but the estimate was too 
imprecise to determine whether this was likely to reflect a true difference in 
complication rates. This was also the case for rates of further surgical 
intervention (OR 1.4, 95% CI 0.31 to 6.24, n = 42). There were no deaths during 
the trial. We judged the quality of evidence for all outcomes to be very low 
because of a high risk of selection, attrition and reporting bias and serious 
imprecision in the results.
AUTHORS' CONCLUSIONS: The only randomised trial of ETV for iNPH compares it to 
an intervention which is not a standard practice (VP shunting using a 
non-programmable valve). The evidence from this study is inconclusive and of 
very low quality. Clinicians should be aware of the limitations of the evidence. 
There is a need for more robust research on this topic to be able to determine 
the effectiveness of ETV in patients with iNPH.