Month: May 2013

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Role of Endoscopic Third Ventriculostomy and Ventriculoperitoneal Shunt in Idiopathic Normal Pressure Hydrocephalus: Preliminary Results of a Randomized Clinical Trial

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Neurosurgery 72:845–854, 2013

Currently, the most common treatment for idiopathic normal pressure hydrocephalus (INPH) is a ventriculoperitoneal shunt (VPS), generally with programmable valve implantation. Endoscopic third ventriculostomy (ETV) is another treatment option, and it does not require prosthesis implantation.

OBJECTIVE: To compare the functional neurological outcome in patients after 12 months of treatment with INPH by using 2 different techniques: ETV or VPS.

METHODS: Randomized, parallel, open-label trial involving the study of 42 patients with INPH and a positive response to the tap test, from January 2009 to January 2012. ETV was performed with a rigid endoscope with a 30 lens (Minop, Aesculap), and VPS was performed with a fixed-pressure valve (PS Medical, Medtronic). The outcome was assessed 12 months after surgery. The neurological function outcomes were based on the results of 6 clinical scales: mini-mental, Berg balance, dynamic gait index, functional independence measure, timed up and go, and normal pressure hydrocephalus.

RESULTS: There was a statistically significant difference between the 2 groups after 12 months of follow-ups, and the VPS group showed better improvement results (ETV = 50%, VPS = 76.9%).

CONCLUSION: Compared with ETV, VPS is a superior method because it had better functional neurological outcomes 12 months after surgery.

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Is endoscopic third ventriculostomy superior to shunts in patients with non-communicating hydrocephalus?

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Acta Neurochir (2013) 155:883–889

Endoscopic third ventriculostomy (ETV) and shunts are both utilized in the treatment of noncommunicating hydrocephalus. The objective of this study was to review the evidence comparing the effectiveness of these two techniques.

Methods The Cochrane Central Register of Controlled Trials (CENTRAL) and Medline databases were searched between 1990 and August 2012. We included all studies comparing the failure rate of patients with noncommunicating hydrocephalus treated with ETVand shunts. Two authors (HJM and FTR) appraised quality and extracted data independently.

Results Of 313 articles identified, 12 were selected for further review. Of these, 6 were included for qualitative analysis, and 5 for quantitative analysis (n=504). ETV was associated with a non-statistically significant reduction in failure using the random-effects model (OR 0.58, 95 % CI 0.29-1.13).

Conclusions Both ETV and shunts are associated with a relatively high failure rate. At present there is insufficient proof to unequivocally recommend one mode of treatment above the other. However, there is some evidence that ETV may confer long-term survival advantage over shunts in the treatment of non-communicating hydrocephalus, particularly in patients with certain aetiologies such as aqueductal stenosis. Prospective randomized controlled trials are currently underway and may provide more robust evidence to answer this important question and better guide future management.

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The Silent Loss of Neuronavigation Accuracy

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Neurosurgery 72:796–807, 2013

Neuronavigation has become an intrinsic part of preoperative surgical planning and surgical procedures. However, many surgeons have the impression that accuracy decreases during surgery.

OBJECTIVE: To quantify the decrease of neuronavigation accuracy and identify possible origins, we performed a retrospective quality-control study.

METHODS: Between April and July 2011, a neuronavigation system was used in conjunction with a specially prepared head holder in 55 consecutive patients. Two different neuronavigation systems were investigated separately. Coregistration was performed with laser-surface matching, paired-point matching using skin fiducials, anatomic landmarks, or bone screws. The initial target registration error (TRE1) was measured using the nasion as the anatomic landmark. Then, after draping and during surgery, the accuracy was checked at predefined procedural landmark steps (Mayfield measurement point and bone measurement point), and deviations were recorded.

RESULTS: After initial coregistration, the mean (SD) TRE1 was 2.9 (3.3) mm. The TRE1 was significantly dependent on patient positioning, lesion localization, type of neuroimaging, and coregistration method. The following procedures decreased neuronavigation accuracy: attachment of surgical drapes (DTRE2 = 2.7 [1.7] mm), skin retractor attachment (DTRE3 = 1.2 [1.0] mm), craniotomy (DTRE3 = 1.0 [1.4] mm), and Halo ring installation (DTRE3 = 0.5 [0.5] mm). Surgery duration was a significant factor also; the overall DTRE was 1.3 [1.5] mm after 30 minutes and increased to 4.4 [1.8] mm after 5.5 hours of surgery.

CONCLUSION: After registration, there is an ongoing loss of neuronavigation accuracy. The major factors were draping, attachment of skin retractors, and duration of surgery. Surgeons should be aware of this silent loss of accuracy when using neuronavigation.

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