Interpretation of telemetric intracranial pressure recordings in people with idiopathic intracranial hypertension after shunt implantation.

BACKGROUND: The M.scio telesensor (Aesculap-Miethke, Germany) is a device integrated within a ventriculoperitoneal (VP) shunt for non-invasive measurement of the intracranial pressure (ICP). The purpose of this study was to analyze the telemetric recordings with the M.scio system in shunted patients with idiopathic intracranial hypertension (IIH), in order to determine reference values and assist the interpretation of telemetric data. METHODS: This was a cohort study of consecutive patients with fulminant IIH who underwent primary VP shunt insertion between July 2019 and June 2022. The first telemetric measurements after surgery in the sitting and supine positions were analyzed. Telemetric ICP values, wave morphology, and pulse amplitude were determined for functioning and malfunctioning shunts. RESULTS: Fifty-seven out of 64 patients had available telemetric recordings. The mean ICP was - 3.8 mmHg (standard deviation (SD) = 5.9) in the sitting and 16.4 mmHg (SD = 6.3) in the supine position. The ICP curve demonstrated pulsatility in 49 (86%) patients. A pulsatile curve with mean ICP in the above ranges indicated a functioning shunt, whereas the lack of pulsatility was challenging to interpret. There was a significant positive correlation between ICP versus amplitude, ICP versus body mass index (BMI), and amplitude versus BMI. CONCLUSIONS: This clinical study defined ICP values and curves in IIH patients with a shunt. The results will assist the interpretation of telemetric ICP recordings in clinical decision making. More research is required to model longitudinal recordings and explore the link between telemetric measurements with clinical outcomes.

Defining the Phenotype and Prognosis of People With Idiopathic Intracranial Hypertension After Cerebrospinal Fluid Diversion Surgery.

PURPOSE: To characterize the phenotype of patients with idiopathic intracranial hypertension (IIH) who received cerebrospinal (CSF) diversion surgery and to detail the trajectory of recovery. DESIGN: Prospective cohort registry study. METHODS: Patients with IIH with sight-threatening papilledema presenting to a single United Kingdom neuroscience center between 2019 and 2021 were included. Outcomes consisted of perimetric mean deviation (PMD) and optical coherence tomography measures of papilledema (retinal nerve fiber layer [RNFL]) and macular ganglion cell layer (GCL) in both eyes. Headache outcomes included monthly headache days (MHD). Logistic regression methods were used to model long-term outcomes. RESULTS: Fifty-one patients without previous surgical interventions were included (92% female, mean age 28.1 years [SD 8.4], body mass index 37.4 kg/m2 [SD 9.7], mean days of follow-up 330 [SD 209]). Measurements before surgery showed mean PMD -11.4 dB (SD 9.7), RNFL 364 µm (SD 128), Frisén grade papilledema 4.3 (SD 0.9). and MHD 23 (SD 10.6). At 1 month postoperatively, RNFL and PMD had improved by 38% and 4%, respectively. At 4 months postoperatively, papilledema had resolved. GCL declined by 13% over 12 months. MHD reduced by 75% 3 months postoperatively before returning to baseline levels by 12 months. Five patients (9.8%) required revision surgeries. CONCLUSIONS: Detailed characteristics of patients with sight-threatening IIH who received CSF diversion surgery and their typical postoperative recovery are presented. These parameters should guide physicians as to when patients with IIH may require surgery and enable the early identification of outliers who fail to respond. Papilledema and PMD recovered but GCL atrophy continued for 12 months. The implication of this delayed atrophy is unknown.

The Birmingham Standardized Idiopathic Intracranial Hypertension Shunt Protocol: Technical Note.

BACKGROUND: Insertion of cerebrospinal fluid (CSF) shunts in patients with idiopathic intracranial hypertension (IIH) is challenging mainly due to the small ventricles and phenotypical body habitus. In this report the authors present their surgical protocol for insertion of a ventriculoperitoneal shunt (VPS) in patients with IIH and the associated revision rates. METHODS: The protocol comprises the following: shunt surgery by neurosurgeons with expertise in CSF disorders; a frontal VPS usually right sided but left sided if the left ventricle is bigger; use of the proGAV 2.0 valve with gravitational unit, set at 10 and the M.scio telemetric sensor; cannulation of the ventricle with StealthStation EM navigation system; and laparoscopic insertion of the peritoneal catheter. The authors describe the protocol and rationale and evidence behind each component and present the results of a prospective analysis on revision rates. RESULTS: The protocol has been implemented since 1 July, 2019, and by 28 February, 2022, sixty-two patients with IIH had undergone primary VPS insertion. The 30-day revision rate was 6.5%, and overall 11.3% of patients underwent revision during the study period, which compares favorably with the literature. The etiology for early failures was related to the surgical technique. CONCLUSIONS: The components of the Birmingham standardized IIH shunt protocol are evidence based and address the technical challenges of CSF diversion in patients with IIH. This protocol is associated with a low revision rate, and the authors recommend standardization for CSF shunting in IIH.

Cerebrospinal fluid shunting protocol for idiopathic intracranial hypertension for an improved revision rate.

OBJECTIVE: Cerebrospinal fluid (CSF) shunting in idiopathic intracranial hypertension (IIH) is associated with high complication rates, primarily because of the technical challenges that are related to small ventricles and a large body habitus. In this study, the authors report the benefits of a standardized protocol for CSF shunting in patients with IIH as relates to shunt revisions. METHODS: This was a retrospective study of consecutive patients with IIH who had undergone primary insertion of a CSF shunt between January 2014 and December 2020 at the authors' hospital. In July 2019, they implemented a surgical protocol for shunting in IIH. This protocol recommended IIH shunt insertion by neurosurgeons with expertise in CSF disorders, a frontal ventriculoperitoneal (VP) shunt with an adjustable gravitational valve and integrated intracranial pressure monitoring device, frameless stereotactic insertion of the ventricular catheter, and laparoscopic insertion of the peritoneal catheter. Thirty-day revision rates before and after implementation of the protocol were compared in order to assess the impact of standardizing shunting for IIH on shunt complications. RESULTS: The 81 patients included in the study were predominantly female (93%), with a mean age of 31 years at primary surgery and mean body mass index (BMI) of 37 kg/m2. Forty-five patients underwent primary surgery prior to implementation of the protocol and 36 patients after. Overall, 12 (15%) of 81 patients needed CSF shunt revision in the first 30 days, 10 before and 2 after introduction of the protocol. This represented a significant reduction in the early revision rate from 22% to 6% after the protocol (p = 0.036). The most common cause of shunt revision for the whole cohort was migration or misplacement of the peritoneal catheter, occurring in 6 of the 12 patients. Patients with a higher BMI were significantly more likely to have a shunt revision within 30 days (p = 0.022). CONCLUSIONS: The Birmingham standardized IIH shunt protocol resulted in a significant reduction in revisions within 30 days of primary shunt surgery in patients with IIH. The authors recommend standardization for shunting in IIH as a method for improving surgical outcomes. They support the notion of subspecialization for IIH shunts, the use of a frontal VP shunt with sophisticated technology, and laparoscopic insertion of the peritoneal end.