The Impact of Multimorbidity Burden, Frailty Risk Scoring, and 3-Directional Morphological Indices vs. Testing for CSF Responsiveness in Normal Pressure Hydrocephalus

Objective: Multimorbidity burden across disease cohorts and variations in clinico-radiographic presentations within normal pressure hydrocephalus (NPH) confound its diagnosis, and the assessment of its amenability to interventions. We hypothesized that novel imaging techniques such as 3-directional linear morphological indices could help in distinguishing between hydrocephalus vs. non-hydrocephalus and correlate with responsiveness to external lumbar drainage (CSF responsiveness) within NPH subtypes.Methodology: Twenty-one participants with NPH were recruited and age-matched to 21 patients with Alzheimer’s Disease (AD) and 21 healthy controls (HC) selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Patients with NPH underwent testing via the NPH programme with external lumbar drainage (ELD); pre- and post-ELD MRI scans were obtained. The modified Frailty Index (mFI-11) was used to stratify the NPH cohort, including Classic and Complex subtypes, by their comorbidity and frailty risks. The quantitative imaging network tool 3D Slicer was used to derive traditional 2-dimensional (2d) linear measures; Evans Index (EI), Bicaudate Index (BCI) and Callosal Angle (CA), along with novel 3-directional (3d) linear measures; z-Evans Index and Brain per Ventricle Ratio (BVR). 3-Dimensional (3D) ventricular volumetry was performed as an independent correlate of ventriculomegaly to CSF responsiveness.Results: Mean age for study participants was 71.14 ± 6.3 years (18, 85.7% males). The majority (15/21, 71.4%) of participants with NPH comprised the Complex subtype (overlay from vascular risk burden and AD); 12/21 (57.1%) were Non-Responders to ELD. Frailty alone was insufficient in distinguishing between NPH subtypes. By contrast, 3d linear measures distinguished NPH from both AD and HC cohorts, but also correlated to CSF responsiveness. The z-Evans Index was the most sensitive volumetric measure of CSF responsiveness (p = 0.012). Changes in 3d morphological indices across timepoints distinguished between Responders vs. Non-Responders to lumbar testing. There was a significant reduction of indices, only in Non-Responders and across multiple measures (z-Evans Index; p = 0.001, BVR at PC; p = 0.024). This was due to a significant decrease in ventricular measurement (p = 0.005) that correlated to independent 3D volumetry (p = 0.008).Conclusion. In the context of multimorbidity burden, frailty risks and overlay from neurodegenerative disease, 3d morphological indices demonstrated utility in distinguishing hydrocephalus vs. non-hydrocephalus and degree of CSF responsiveness. Further work may support the characterization of patients with Complex NPH who would best benefit from the risks of interventions.

External Lumbar Drainage for Refractory Intracranial Hypertension in Traumatic Brain Injury: A Systematic Review

BackgroundExternal lumbar drainage remains a controversial therapy for medically refractory intracranial hypertension in patients with acute TBI. This systematic review sought to compile the available evidence for the efficacy and safety of the use of lumbar drains for ICP control. MethodsA systematic review of the literature was performed with the search and data extraction performed by two reviewers independently in duplicate.ResultsNine independent studies were identified enrolling 230 patients, 159 with TBI. Efficacy for ICP control was observed across all studies, with immediate and sustained effect, reducing medical therapy requirements. Lumbar drainage with medical therapy appears effective when used alone and as an adjunct to ventricular drainage. Safety reporting varied in quality. Cerebral herniation (with unclear relationship to lumbar drainage) was observed in 14/230 patients resulting in one incident of morbidity without adverse patient outcome. ConclusionsThe available data is generally poor in quality and volume, but supportive of efficacy of lumbar drainage for ICP control. Few reports of adverse outcome are suggestive of, but are insufficient to confirm, safety of use in the appropriate patient and clinical setting. Further large prospective observational studies are required to generate sufficient support of an acceptable safety profile.

External lumbar drainage in progressive pediatric idiopathic intracranial hypertension

OBJECTIVE Pediatric idiopathic intracranial hypertension (IIH) is characterized by increased intracranial pressure despite normal cerebrospinal fluid and neuroimaging findings. Initial management is typically medical; however, nearly 10% of children will eventually require surgery for persistent headache and/or vision loss. External lumbar drainage, which is a considerably safer treatment option, has not been adequately analyzed in children with medically refractory IIH. METHODS The authors conducted a single-institution retrospective analysis of children with medically refractory IIH who had undergone external lumbar drain (ELD) placement because of worsening papilledema, reflected as increased retinal nerve fiber layer (RNFL) thickness on optical coherence tomography (OCT) testing. The main outcome measures were effects of external lumbar drainage on papilledema resolution, symptoms, and vision. RESULTS The authors analyzed the medical records of 13 children with IIH (11 girls, mean age 15.0 ± 2.3 years) whose mean CSF opening pressure was 45.5 ± 6.8 cm H2O. In all children, the average global RNFL thickness in both eyes significantly increased at ELD placement (right eye 371.8 ± 150.2 μm, left eye 400.3 ± 96.9 μm) compared with presentation thickness (right eye 301.6 ± 110.40 μm, left eye 350.2 ± 107.7 μm) despite acetazolamide medical therapy (20–30 mg/kg/day), leading to ELD placement after 9.5 ± 6.9 days (range 3–29 days). After ELD insertion, there was headache resolution, gradual and continuous improvement in optic disc thickness, and preservation of good vision. CONCLUSIONS ELD placement in children with medically refractory IIH who demonstrated worsening papilledema with increased RNFL thickening on OCT testing typically results in symptom relief and disc edema resolution with good visual outcome, often preventing the need for additional definitive surgeries that carry greater failure and morbidity risks.

Rupture of a Previously Undiagnosed Anterior Communicating Artery Aneurysm following External Lumbar Drainage in a Patient with Normal Pressure Hydrocephalus: A Case Report

Background and importance: Both asymptomatic unruptured intracranial aneurysms (AUIA) and idiopathic normal pressure hydrocephalus (NPH) have been found in the elderly population to increase in incidence with advancing age. In NPH, external lumbar drainage (ELD) is a gold standard and widely accepted low-risk procedure for supplemental testing of CSF responsiveness and suitability for surgical intervention. Herein, we reported the first case of aneurysmal subarachnoid haemorrhage (SAH) as a cause of neurological decline following ELD for the testing of patients with NPH. Clinical Presentation: A 65-year-old gentleman with probable NPH was admitted for supplemental testing using ELD. He had demonstrated CSF responsiveness as evidenced by improving Tinetti score. Unfortunately, on the third day of post-insertion, his GCS deteriorated from 15 to 3 due to rupture of a previously undiagnosed anterior communicating artery (Acom) aneurysm. He underwent left frontal external ventricular drain in an emergency setting and his GCS improved to E1VtM4. After frank discussion with his family, we proceeded with craniotomy and clipping of the aneurysm. However, his neurological recovery remained poor post-operatively and he had eventually undergone tracheostomy and ventriculo-peritoneal shunt. Conclusion: As SAH is also a known trigger of secondary NPH, there may be a critical role for screening of AUIA prior to ELD for NPH. The characterization of this risk would then allow for a full discussion of surgical or endovascular treatment options for AUIA, as well as the risk-benefit ratio of proceeding with supplemental testing and intervention for NPH.

Invasive preoperative diagnosis of idiopathic normal pressure hydrocephalus

Introduction. Until now, the most informative methods for selecting patients with idiopathic normal pressure (iNPH) for neurosurgical treatment were invasive diagnostic methods: tap test, lumbar infusion test, external lumbar drainage. Nevertheless, choosing the sequence of using these diagnostic tools and the assessment of their results cause number of questions for doctors in everyday practice.The study objective is to assess the informational content of invasive tests for differential diagnosis of iNPH and to create an algorithm of applying mentioned methods for clinical purposes.Materials and methods. At least one of the invasive diagnostic methods was used for 374 patients, who were treated in the period from 2006 to 2018 in the neurosurgical clinic of S. M. Kirov Military Medical Academy. The patients with final diagnosis of iNPH (n = 231), aged 58–87 years old, were selected for shunt surgery. The informativeness measures were calculated for each method on the basis of revealed data.Results. Sensitivity and specificity of tap test were 57.5 and 86.4 %, respectively, positive predictive value – 92.5 %, negative predictive value – 41.3 %, accuracy – 64.9 %. For lumbar infusion test sensitivity was 39.1 %, specificity – 63.6 %, but we calculated low negative predictive value (20.0 %) and accuracy (43.9 %) of the method despite of relatively high positive predictive value (81.8 %). External lumbar drainage revealed the highest significance of positive predictive value (92.9 %).Conclusion. Excluding of lumbar infusion test from the pre-operative diagnostic algorithm of iNPH and recommendation for sequential using of tap-test and external lumbar drainage after questionable result of the last one are an advisable option for practitioners.

Sinking Skin Flap Syndrome and Paradoxical Herniation Provoked by a Malfunction of External Lumbar Drainage and CSF Leak

The sinking skin flap syndrome represents a less-frequent complication in patients after a decompressive craniectomy. It is defined as a neurological deterioration accompanied by a flat or concave deformity of the craniectomy-related skin flap. The underlying brain parenchyma is distorted correspondingly with its blood flow and metabolism being impaired and cerebrospinal fluid hydrodynamics being disturbed, thus causing cerebral dysfunction and neurological symptomatology. The most important options for reversal of this syndrome include Trendelenburg position, maintaining of the cerebrospinal fluid balance, and cranioplasty as a definite solution. We present a patient who underwent a decompressive craniectomy complicated by a cerebrospinal fluid leak in the operative wound treated by means of an external lumbar drainage. Subsequently he developed the sinking skin flap syndrome and a paradoxical cerebral herniation after the drainage system malfunction with a massive cerebrospinal fluid leak at the site of the lumbar drain insertion parallel to the drain itself. His symptoms were, however, successfully alleviated by a positional change, rehydration, and interruption of the lumbar drainage. This illustrational case suggests that clinicians should be aware that patients after decompressive craniectomy may develop a sinking skin flap syndrome as it may either represent an acute risk of a paradoxical brain herniation or complicate the further postoperative care if developed in a chronic way.