Wednesday, May 27, 2020

When neglect is neglected: NIHSS observational measure lacks sensitivity in identifying post-stroke unilateral neglect

Well shit, the solution to this is protocols that if they aren't followed lead to firings.  Patients could easily ensure they are being followed by just looking in the publicly available database of them when we get survivors in charge.  

When neglect is neglected: NIHSS observational measure lacks sensitivity in identifying post-stroke unilateral neglect

 

  1. Margaret Jane Moore,
  2. Kathleen Vancleef,
  3. Nir Shalev,
  4. Masud Husain,
  5. Nele Demeyere

Author affiliations




Introduction

Unilateral visual neglect is characterised by lateralised spatial–attentional deficits, resulting in dramatic behavioural impairments.1 Neglect negatively impacts functional outcome and needs to be successfully detected in order to inform neglect-specific as well as general post-stroke rehabilitation goals and strategies. It is therefore critically important to evaluate current clinical methods for detecting and measuring the extent of this syndrome.
Observational neurological assessments, such as the National Institutes of Health Stroke Scale (NIHSS), rely predominantly on subjective impression of impairment levels rather than objective measurements.2 Although the NIHSS was not designed as an individual diagnostic tool, it is frequently employed as one. However, previous research has suggested that observational assessments may not be sufficiently sensitive to visual neglect.2–4 The purpose of this study was to evaluate the diagnostic sensitivity of the NIHSS’ visual neglect item compared with a brief neuropsychological cancellation test and to identify factors which modulate this sensitivity.

Methods

428 patients who had an acute stroke (mean age, 71 (SD 12.8); mean time post-stroke, 7.3 days (SD 7.4)) completed the NIHSS and Oxford Cognitive Screen (OCS) Cancellation Task (mean interval, 1.2 days). 63.1% of patients completed both tests on the same day and the NIHSS was administered first in 33.9% of cases. The NIHSS Extinction/Inattention and Visual Field items were considered in this investigation, with Extinction/Inattention scores of 0 (none), 1 (mild) or 2 (profound) and Visual Field scores of 0 (normal), 1 (partial) or 2 (complete).
The OCS is a brief stroke-specific cognitive screen which includes a highly sensitive Cancellation Task.5 This test was therefore used as the comparison standard for NIHSS sensitivity calculations. In this Cancellation Task, patients are instructed to search for and mark complete heart outlines while ignoring incomplete hearts. Egocentric neglect was scored by subtracting the number of targets identified on the left and right side of the page while allocentric neglect was scored by subtracting the number of right-gap and left-gap hearts identified. Egocentric asymmetries larger than 3 and allocentric asymmetries greater than 1 represent significant impairment.5

Results

First, the sensitivity of the NIHSS to neglect was evaluated. 83/428 (19.4%) and 199/428 (46.5%) patients exhibited neglect as reported by the NIHSS and OCS, respectively. In comparison with the OCS, the NIHSS exhibited a high neglect specificity (91.2%), though a low sensitivity (31.6%). Interestingly, the Extinction/Inattention Item was not found to be significantly more sensitive to neglect than the Visual Field Item (sensitivity, 28.1%; McNemar’s, χ2=0.735, p=0.39).
Next, the relationship between NIHSS sensitivity and neglect severity was investigated (figure 1). A regression analysis demonstrated that patients with milder neglect on the OCS cancellation were significantly less likely to be identified by the NIHSS than patients with more severe neglect (R2=0.107, F(1,42)=5.016, p=0.030, β=−0.327). Similarly, there was a significant difference in cancellation total for neglect patients with different Extinction/Inattention Item scores (F(2,169)=4.777, p=0.010). However, there was large individual variability in all NIHSS item severity categories and the NIHSS was still found to have a low sensitivity (38.1%) when only the most severe neglect patients (cancellation totals <10/50) were considered.
Figure 1
(A) Illustration of the relationship between cancellation score and National Institutes of Health Stroke Scale (NIHSS) sensitivity. The number of neglect cases of each severity level is denoted by bar height (right y-axis). Cases which were successfully identified by the NIHSS are blue and missed cases are red. The sensitivity linear regression line is plotted as the dashed line. (B) Relationship between NIHSS Inattention/Extinction Score and Oxford Cognitive Screen (OCS) Cancellation Task score egocentric neglect patients. Score distribution is represented by plot width, points represent individual cases, and rectangles represent upper and lower quartiles. Lower cancellation scores represent more severe neglect. *p<0.05.
Finally, the relationship between neglect subtypes and NIHSS sensitivity was investigated. The NIHSS was found to be more likely

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