Article
CSF upward motion crucial for ETV success?
Ist die Aufwärtsbewegung des Liquors wichtig für den ETV-Erfolg?
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Published: | June 4, 2021 |
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Objective: ETV is indicated for treating obstructions of major CSF pathways, ventricular dilation and hydrocephalus complaints. Despite these parameters the outcome evaluation yields success rates of not more than 60-70% for shunt independency. Hence compromised CSF absorption seems to occur more often than expected. Beside the time scale of obstruction, we have extended the search for parameters suitable to assess involved CSF dynamics.
Methods: Prospective study in 55 pediatric patients (8 yrs. mean) between 2000 and 2020 with aquaeductal stenosis, Chiari- and Dandy Walker malformation showing different grades of ventricle outlet obstruction with escalating head circumference, elevated Evans- and FOH-Ratios, spontaneously perforated septum pellucidum over 5 years mean follow up time. All patients underwent MRIs pre- and postoperatively. Success was defined as abatement of complaints, papilledema and elevated head circumference, flow void signals through the stoma. Social outcome like protected education was documented. Four patients were studied pre-and postoperatively by real time (RT) MRI CSF flow studies.
Results: In 70.9% bowing of the floor of the 3rd ventricle was observable. 49% of the children had spontaneous septal perforations, parachute signs or an open aqueduct before ETV (36%). ∆ER and ∆FOHR were reduced by ETV for 0.04 and 0.06 (mean) respectively. Opened stoma with flow void signs were found in 81%. Previously obstructed aqueducts post ETV open without addressing the aqueduct occurred in 12.7%. Increase of head circumference stopped in 65.4%. Shunt insertion in cases of developmental delay and persistent papilledema was estimated as 29%, re-ETV in 2 cases. The mean interval for shunt insertion after ETV was 97 days (Max=556d). CSF upward motion intraoperatively was regularly observed (video 1). Flow passing the patent stoma could be demonstrated by RT-MRI in 3 patients (video 2) in contrast to one failed ETV. Regular education correlated significantly (p<0.05) with ventricular volumetry and postoperative size ratios.
Conclusion: Challenging concepts of CSF dynamics have come into focus during the last 5 years. Understanding hydrocephalus with perturbated resorptive capacities of the glymphatic system focus on sustained alterations induced by obstructive structures. Enabling CSF upward flow driven by inspiration seems crucial for successful ETV and restored resorptive capacity.