Assessment of CSF Dynamics Using Infusion Study: Tips and Tricks.

Idiopathic normal pressure hydrocephalus, secondary chronic hydrocephalus, and other cerebrospinal fluid (CSF) disorders are often challenging to diagnose. Since shunt surgery is usually the only therapeutic option and carries significant morbidity, optimal patient selection is crucial. The tap test is the most commonly used prognostic test to confirm the diagnosis but lacks sensitivity. The lumbar infusion study (LIS) appears to be a better option, offering additional information on brain dynamics without increasing morbidity. However, this technique remains underused. In this narrative review, supported by the extensive experience of several European expert centers, we detail the physiological basis, indications, and CSF dynamics parameters that can be measured. We also discuss technical modalities and variations, including one versus 2 needles, patient positioning, and the site of CSF measurement, as well as in vivo shunt testing. Finally, we discuss the limitations and morbidity associated with the LIS. This review aims to assist teams wishing to incorporate LIS into their screening tools for chronic hydrocephalus and other CSF disorders.

INPH and parkinsonism: A positive shunt response with a negative tap test.

Introduction: The aim of this study was to compare clinical and functional performances of idiopathic normal pressure hydrocephalus (INPH) patients with and without parkinsonism at the initial evaluation, 72 h after the cerebrospinal fluid tap test (CSF TT), and 6 months after ventriculoperitoneal shunt (VPS) surgery. Materials and methods: This is an observational prospective study on patients with INPH who underwent VPS. Patients were classified into INPH with parkinsonism (INPH-P+) and without parkinsonism (INPH-P-). We used the time up and go (TUG) test, Tinetti Performance-Oriented Mobility Assessment (POMA) test, INPH grading scale (INHPGS), and modified Rankin scale (mRS) at baseline, 72 h after CSF TT, and 6 months after VPS surgery. Results: A total of 64 patients with probable INPH were included, 12 patients with INPH-P+ and 52 controls with INPH-P-. Patients with INPH showed significant improvement in all clinical and neurological parameters after VPS including TUG, Tinetti POMA, INPHGS, and mRS (p < 0.001) with the exception of mRS where there was no significant change 72 h after CSF TT compared to baseline for patients with INPH (p = 0.182). Patients with INPH-P+ performed significantly worse than patients with INPH-P- on Tinetti POMA and mRS at baseline, at 72 h post-CSF TT, and at 6 months post-VPS with INPHGS being worst at 72 h post-CSF TT. There was no difference between patients with INPH-P+ and patients with INPH-P- for TUG at baseline (p = 0.270), at 72 h post-CSF TT (p = 0.487), and at 6 months post-VPS (p = 0.182). Patients with INPH-P+ did not show any change in any of the parameters at 72 h post-CSF TT compared to baseline; however, there was a trend toward improvement on TUG (p = 0.058), Tinetti gait (p = 0.062), and Tinetti total (p = 0.067). INPH-P+ significantly improved in all parameters 6 months post-VPS compared to baseline except for mRS (p = 0.124). Patients with INPH-P- significantly improved in all parameters at 72 h post-CSF TT and at 6 months post-VPS compared to baseline, respectively, except on mRS 72 h after CSF TT (p = 0.299). Conclusion: Patients with INPH and parkinsonism overall do worse than patients without parkinsonism. An unsatisfying response to the CSF tap test in INPH patients with parkinsonism should not be used as an exclusion criterion from VPS surgery since patients with and without parkinsonism showed significant improvement post-VPS.

CSF dynamics in long-standing overt ventriculomegaly in adults.

OBJECTIVE: Long-standing overt ventriculomegaly in adults (LOVA) is a form of chronic hydrocephalus and its pathophysiology and treatment remain debated. An analysis of CSF dynamics in this condition has rarely been reported. The aim of this study was to analyze hydrodynamic characteristics of patients with suspected LOVA to discuss its pathophysiological mechanisms and the importance of CSF dynamics analysis for diagnosis and treatment of these patients. METHODS: This retrospective cohort study, conducted between May 2018 and October 2022, included adult patients aged > 18 years investigated in a department of neurosurgery through a lumbar infusion study for suspicion of LOVA (n = 23). These patients were then compared with a control cohort explored for suspicion of idiopathic normal pressure hydrocephalus (iNPH; n = 30). Clinical symptoms, radiological findings, and hydrodynamic parameters were analyzed. The authors specifically compared two hydrodynamic parameters: resistance to CSF outflow, or Rout, which relies on CSF resorption, and pressure-volume index (PVI), which reflect overall craniospinal compliance. The lumbar infusion study was considered pathological (confirming the diagnosis of chronic hydrocephalus) when at least one of these two parameters was altered. RESULTS: Rout was significantly less frequently increased (cutoff ≥ 12 mm Hg/ml/min) in patients with LOVA (52%) than in those with iNPH (97%; p < 0.001). In contrast, PVI was impaired (cutoff ≤ 25 ml) in both cohorts, i.e., in 61% of patients with LOVA and in 83% of patients with iNPH. Overall, the rate of pathological lumbar infusion study in LOVA (87%) was not statistically different than in iNPH (100%). However, PVI was the only impaired parameter most frequently found in those with LOVA (35%) compared with those with iNPH (3%; p = 0.002). CONCLUSIONS: This study suggests that there is a differential CSF dynamics pattern when comparing patients with LOVA versus those with iNPH. A higher proportion of patients with LOVA showed isolated compliance impairment. These findings highlight the utility of CSF dynamics analysis for the evaluation of patients with suspected chronic obstructive hydrocephalus such as LOVA. Future research with larger case series may help define diagnosis and treatment algorithms of chronic obstructive hydrocephalus based on CSF dynamics analysis, in addition to clinical and radiological criteria.

Ventriculoatrial Shunt Under Locoregional Anesthesia: A Technical Note.

BACKGROUND: Ventriculoatrial shunt is routinely performed under general anesthesia and is used to treat various kinds of hydrocephalus. Idiopathic normal pressure hydrocephalus patients are generally elderly and can have high comorbidities; in such patients, avoiding general anesthesia and limiting opioid administration could be beneficial. We started to perform ventriculoatrial shunt under locoregional anesthesia, in order to make this procedure more truly "minimally invasive". METHODS: Demographic data, American Society of Anesthesiologists (ASA) score and vital signs, Ramsay sedation scale, and procedural duration were collected. All procedures were performed combining sedation with cervical plexus and scalp block. After internal jugular vein cannulation, a catheter was inserted and connected with a programmable valve and then with the ventricular catheter. Outcome was assessed by the Idiopathic Normal Pressure Hydrocephalus Grading Scale and complications were recorded at 3-month follow-up. RESULTS: Ten consecutive patients were enrolled; the mean age was 74 years, 8 were male, ASA score median value was 3. Opioids were administered only in 4 patients, in 6 patients the value of Ramsay scale was 5. The average duration of surgery was 59.5 minutes. No procedure was converted to general anesthesia. CONCLUSIONS: Our preliminary experience with ventriculoatrial shunt under locoregional anesthesia demonstrates that this technique is feasible, is not associated with an increase in operating times or complications, can avoid general anesthesia, and helps to limit opioid administration in the elderly. It can therefore represent a valid option in order to improve treatment quality in these complex patients.

Fenestration of Symptomatic Ventriculus Terminalis: 2-Dimensional Operative Video.

This is a case of a 73 yr-old female presenting with low back pain and bilateral sciatic pain, which progressed to bilateral lower extremity weakness about 1 yr after initial presentation. Imaging of her thoraco-lumbar spine revealed a ventriculus terminalis extending from the level of the eleventh thoracic vertebra (T11) to the first lumbar vertebra (L1). Ventriculus terminalis is an embryological ependymal lined cavity that normally regresses with development. In individuals with persistent ventriculus terminalis, it is usually incidentally noted during spine imaging for other purposes. Surgery is seldom indicated except for patients presenting with progressive neurological deficits. Patient was taken to surgery for fenestration of the ventriculus and decompression of the spinal canal. The patient was positioned prone, and after proper localization the vertebral column was exposed through a midline approach and a central laminectomy was performed from T11-L1. Intraoperative monitoring was used throughout the procedure. This video illustrates the gross appearance of a ventriculus terminalis, dissection of surrounding neural elements, and decompression of the ventriculus using a wide fenestration technique. All relevant patient identifiers have been removed from the video. Nevertheless, patient consent was obtained regarding video recording and redistribution of procedure for educational purposes.