Detection of delayed cerebral ischemia using objective pupillometry in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

Cerebral vasospasm causing delayed cerebral ischemia (DCI) is a source of significant morbidity after subarachnoid hemorrhage (SAH). Transcranial Doppler is used at most institutions to detect sonographic vasospasm but has poor positive predictive value for DCI. Automated assessment of the pupillary light reflex has been increasingly used as a reliable way of assessing pupillary reactivity, and the Neurological Pupil Index (NPi) has been shown to decrease hours prior to the clinical manifestation of ischemic injury or herniation syndromes. The aim of this study was to investigate the role of automated pupillometry in the setting of SAH, as a potential adjunct to TCD.

METHODS

Our analysis included patients that had been diagnosed with aneurysmal SAH and admitted to the neuro–intensive care unit of the University of Texas Southwestern Medical Center between November 2015 and June 2017. A dynamic infrared pupillometer was used for all pupillary measurements. An NPi value ranging from 3 to 5 was considered normal, and from 0 to 2.9 abnormal. Sonographic vasospasm was defined as middle cerebral artery velocities greater than 100 cm/sec with a Lindegaard ratio greater than 3 on either side on transcranial Doppler. Most patients had multiple NPi readings daily and we retained the lowest value for our analysis. We aimed to study the association between DCI and sonographic vasospasm, and DCI and NPi readings.

RESULTS

A total of 56 patients were included in the final analysis with 635 paired observations of daily TCD and NPi data. There was no statistically significant association between the NPi value and the presence of sonographic vasospasm. There was a significant association between DCI and sonographic vasospasm, χ2(1) = 6.4112, p = 0.0113, OR 1.6419 (95% CI 1.1163–2.4150), and between DCI and an abnormal decrease in NPi, χ2(1) = 38.4456, p < 0.001, OR 3.3930 (95% CI 2.2789–5.0517). Twelve patients experienced DCI, with 7 showing a decrease of their NPi to an abnormal range. This change occurred > 8 hours prior to the clinical decline 71.4% of the time. The NPi normalized in all patients after treatment of their vasospasm.

CONCLUSIONS

Isolated sonographic vasospasm does not seem to correlate with NPi changes, as the latter likely reflects an ischemic neurological injury. NPi changes are strongly associated with the advent of DCI and could be an early herald of clinical deterioration.

The Use of Prone Magnetic Resonance Imaging to Rule Out Tethered Cord in Patients With Structural Spine Anomalies: A Diagnostic Technical Note for Surgical Decision-making

Tethered cord syndrome (TCS) is a clinical diagnosis that can be difficult to establish, as symptoms do not always match classic radiological findings, such as a low-lying conus. Surgery for spinal detethering is not without risk and does not always result in clinical improvement. Prone magnetic resonance imaging (MRI) has been described as a tool to assess the mobility of the spine. This is a technical imaging report where prone imaging was a factor that influenced the decision to defer surgery in favor of conservative management. T1 and T2 sagittal and T1 axial MRI imaging were obtained with the patient supine, and then repeated in the prone position. An anteroposterior conus movement of >10% of the canal width was considered normal. There was significant anterior movement of the conus when switching to the prone position. Surgery was deferred, and the patient improved after a regimen of intensive physical therapy. Prone MRI can be a useful tool to have in our neurosurgical armamentarium when assessing spinal cord tethering. Surgery is not recommended when normal anteroposterior movement of the conus is present.

Ventriculoperitoneal Shunt Outcomes of Normal Pressure Hydrocephalus: A Case Series of 116 Patients

Background

Permanent cerebrospinal fluid (CSF) diversion with a ventriculoperitoneal shunt (VPS) is a treatment option for patients with normal pressure hydrocephalus (NPH).

Objectives

Herein, we examine the outcomes, complication rates, and associations between predictors and outcomes after VPS in patients with NPH.

Methods

This was a retrospective review of 116 patients (68 males, 48 females) with NPH who underwent VPS placement from March 2008 to September 2017 after demonstrating objective and/or subjective improvement after a lumbar drain trial. The Chi-square test of independence was used to examine associations between predictors and clinical improvement after shunting. Complications associated with the VPS procedure were recorded.

Results

The mean age was 77 years (range 52-93). The mean duration of disturbance in gait, cognition, and continence were 29, 32, and 28 months, respectively. Of the 116 patients, 111 followed up at two weeks; of these, improvement in gait, incontinence, and cognition were reported in 72, 20, and 23 patients, respectively. Gait improved more than incontinence or cognition. A shorter duration of gait disturbance predicted an improvement in gait after shunting (p<0.01). Being on a cognition-enhancing medication predicted an improvement in cognition and/or incontinence after shunting (p<0.05). Complications included misplaced proximal catheters (n=6), asymptomatic catheter tract hemorrhages (n=3), bilateral hygromas (n=7), subdural hematomas (SDH) (n=5), and CSF leak (n=1).

Conclusion

VPS placement in patients with NPH is well-tolerated and associated with improved outcomes at least in the short-term follow-up (<6 months). A shorter duration of gait disturbance and being on a cognition-enhancing medication are associated with greater improvement after VPS.