Linda d¿antona & claudia louise craven & melida andrea jaime merchan & simon david thompson & fion bremner & lewis thorne & manjit singh matharu & laurence dale watkins & ahmed kassem toma.Paradoxical response of intracranial pressure to shunt valve setting adjustments.Acta neurochirurgica (2020).Doi: 10.1007/s00701-020-04462-y abstract background the hydrodynamics of cerebrospinal fluid shunts have been described in vitro; however, knowledge on the response of intracranial pressure (icp) to valve settings adjustments in vivo is limited.This study describes the effect of adjusting the shunt valve setting on icp in a cohort of patients with complex symptom management.Method single-centre retrospective observational study.Patients who underwent icp-guided valve setting adjustments during 24-h continuous icp monitoring, between 2014 and 2019, were included.Patients with suspected shunt malfunction were excluded.Median night icp before and after the valve adjustments were compared (night icp).The responses of icp to valve adjustment were divided into 3 different groups as follows: expected, paradoxical and no response.The frequency of the paradoxical response and its potential predicting factors were investigated.Results fifty-one patients (37 females, 14 males, mean age 38 years) receiving 94 valve setting adjustments met the study inclusion criteria.Patients¿ underlying conditions were most commonly hydrocephalus (47%) or idiopathic intracranial hypertension (43%).The response of icp to valve setting adjustments was classified as ¿expected¿ in 54 cases (57%), ¿paradoxical¿ in 17 cases (18%) and ¿no effect¿ (night icp < 1 mmhg) in 23 cases (24%).There was a significantcorrelation between the night icp and the magnitude of valve setting change in both the investigated valves (miethke progav, p = 0.01 and medtronic strata, p=0.02).Conclusions paradoxical icp changes can occur after shunt valve setting adjustments.This observation should be taken into account when performing icp-guided valve adjustments and is highly relevant for the future development of ¿smart¿ shunt systems.Reported events.- the effect of the valve setting adjustment on night icp resulted in a ¿paradoxical effect¿ in 4 cases.Paradoxical effect was defined as an ¿upwards¿ valve setting adjustment generating a decrease in night median icp (night icp < - 1 mmhg) or a ¿downwards¿ valve setting adjustment generating an increase in nightmedian icp (night icp > 1 mmhg).See attached literature article.
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