Comparison Between Flow-Regulated and Gravitational Shunt Valves in the Treatment of Normal Pressure Hydrocephalus: Flow-Grav Study

Neurosurgery 89:413–419, 2021

Normal pressure hydrocephalus (NPH) is frequently treated with ventriculoperitoneal shunt (VPS) surgery. However, VPS implantation can lead to overdrainage and complications such as headaches, hygroma, and subdural hematoma due to a siphon effect in an upright position. Gravitational valves prevent overdrainage through positiondependent adjustment of valve resistance. Flow-regulated valves that increase resistance in presence of high cerebrospinal fluid flow may provide similar protection against overdrainage and present an alternative to gravitational valves.

OBJECTIVE: To compare gravitational and flow-regulated shunt valves in patients with symptomatic NPH.

METHODS: We performed a retrospective analysis of 97 patients suffering from NPH who underwent VPS implantation with a gravitational or a flow-regulated valve. The primary endpoint was the occurrence of hygroma or subdural hematoma. Secondary endpoints were neurological outcome (Kiefer score, Stein and Langfitt score, and NPH recovery rate), frequency of valve adjustments, and reoperations.

RESULTS: No significant differences in the occurrence of hygroma and subdural hematoma (11.4% for flow-regulated valves vs 5.7% for gravitational valves, P = .462) or response to treatment (77.3% vs 81.1%, P = .802) were found. Patients with flow-regulated valves required fewer valve adjustments (1.12 vs 2.02, P < .001) to reach their optimal neurological outcome and underwent fewer surgical revisions (11.4% vs 28.3%, P = .047).

CONCLUSION: Our data suggest that shunt therapy in NPH patients with a flow-regulated instead of a gravitational valve is safe and effective with a comparable clinical outcome and risk of overdrainage complications. Moreover, patients with flow-regulated valves may need fewer valve adjustments and reoperations.

Conservative Management of Type II Odontoid Fractures in Older People

Neurosurgery 2020 DOI:10.1093/neuros/nyaa256

Type II odontoid fractures are a common cervical fracture in older people. Lower osseous-union rates are reported in those treated conservatively compared to surgically; however, the clinical relevance of a nonunion is unknown.

OBJECTIVE: To compare pain, disability, and quality of life in older people following conservativemanagement of type II odontoid fractures demonstrating osseous-union and nonunion.

METHODS: Electronic records were searched from 2008 to 2018 for adults ≥65 yr with type II odontoid fracture, managed in a semi-rigid collar. Clinical and demographic data were retrieved from electronic patient notes. Surviving patients were invited to complete questionnaires to assess pain, disability, and quality of life. Ethical approval was granted.

RESULTS: A total of 125 patients were identified: 36 (29%) demonstrated osseous-union, 89 (71%) had nonunion, of which 33 (40%) had radiological instability. Mean age at fracture was 84 yr (osseous-union 83 yr; nonunion 84 yr). A total of 53 had deceased (41 nonunion). Median length of survival was 77 mo for osseous-union vs 50 mo for nonunion; P = .02. No patient developed myelopathy during the follow-up period. Questionnaire response rate was 39 (58%). There were no statistically significant differences between the groups in terms of pain, disability, or quality of life (P>.05). Both groups reported mild disability and pain but low quality of life.

CONCLUSION: Management with a semi-rigid collar in older people with type II odontoid fracture is associated with low levels of pain and disability without statistically significant differences between those demonstrating osseous-union or stable or unstable nonunions. Conservative management appears to be a safe treatment for older people with type II fractures.

Brain Ventricular Size in Healthy Elderly:Comparison Between Evans Index and Volume Measurement

Neurosurgery 67:94-99, 2010 DOI: 10.1227/01.NEU.0000370939.30003.D1

A precise definition of ventricular enlargement is important in the diagnosis of hydrocephalus as well as in assessing central atrophy. The Evans index (EI), a linear ratio between the maximal frontal horn width and the cranium diameter, has been extensively used as an indirect marker of ventricular volume (VV). With modern imaging techniques, brain volume can be directly measured.

OBJECTIVE: To determine reference values of intracranial volumes in healthy elderly individuals and to correlate volumes with the EI.

METHODS:Magnetic resonance imaging (3 T) was performed in 46 healthy white elderly subjects (mean age ± standard deviation, 71 ± 6 years) and in 20 patients (74 ± 7 years) with large ventricles according to visual inspection. VV, relative VV (RVV), and EI were assessed. Ventricular dilation was defined using VV and EI by a value above the 95th percentile range for healthy elderly individuals.

RESULTS: In healthy elderly subjects, we found VV = 37 ± 18 mL, RVV = 2.47 ± 1.17%, and EI = 0.281 ± 0.027. Including the patients, there was a strong correlation between EI and VV (R = 0.94) as well as between EI and RVV (R = 0.95). However, because of a wide 95% prediction interval (VV: ±45 mL; RVV: ± 2.54%), EI did not give a sufficiently good estimate of VV and RVV.

CONCLUSION: VV (or RVV) and the EI reflect different properties. The exclusive use of EI in clinical studies as a marker of enlarged ventricles should be questioned. We suggest that the definition of dilated ventricles in white elderly individuals be defined as VV >77 mL or RVV >4.96 %. Future studies should compare intracranial volumes with clinical characteristics and prognosis.