Western Neuro Sensory Stimulation Profile (WNSSP)

CHAPTER 35: WESTERN NEURO SENSORY STIMULATION PROFILE (WNSSP)

Description

The Western Neuro Sensory Stimulation Profile (WNSSP), by Ansel and Keenan, (1989), was developed to assess cognitive function in severely impaired head-injured adults as well as to monitor and predict change over time. Designed as a measure of responsiveness to structured stimuli, the WNSSP was created in response to the need for an objective measure of both cognitive and communicative function relative to the Rancho Los Amigos Levels of Cognitive Functioning (RLAS) levels 2 to 5, as well as slow to recover individuals such as those who remain at RLAS levels 2 and 3 for extended periods of time. Focused on its ability to identify the emergence from the disorders of consciousness or from a minimally conscious state, the WNSSP presents items with a hierarchy of weighted scores in which higher levels of function receive higher scores suggestive of a recovery sequence (Lannin, Cusick, McLachlan, & Allaous, 2013). The WNSSP has 33 items and is composed of 9 subscales: arousal attention (4 items), auditory response (2 items), auditory comprehension (6 items), expressive communication (3 items), visual tracking (7 items), visual comprehension (5 items), tactile response (2 items), object manipulation (3 items), and olfactory response (1 item). Scoring is based on type of stimulation (general or specific), latency of reaction, as well as the need for cueing (Cusick, Lannin, Hanssen, & Allaous, 2014). Total scores range from 0 to 113 where lower scores indicate poorer function. The assessment takes approximately 45 minutes to complete.

Psychometrics

Original research involving slow to recover traumatic brain injury (TBI) subjects (n = 57) determined the WNSSP to be an ecologically valid assessment in which results showed that internal consistency for the total score was α = 0.95, whereas internal consistency for the subscales of auditory comprehension was 0.87, visual comprehension 0.87, visual tracking 0.95, object manipulation 0.94, arousal/attention 0.73, while for tactile/olfactory it was only 0.59 (Ansell & Keenan, 1989). Inter-rater reliability results using 3 different raters involving 23 subjects found that total and subscales ranged from r = 0.94 to 0.99 except for arousal/attention and tactile/olfactory subscales where correlations ranged from 0.78 to 0.90 and 0.64 to 0.86, respectively (Ansell & Keenan 1989). Later work by Cusick et al. (2014) found internal consistency reliability to be high at α = 0.93 among 33 subjects with severe TBI. The same study found concurrent validity in relation to the Functional Independence Measure (FIM) Scale at discharge to have a modest relationship with the motor subscale (0.37), and the FIM cognition subscale (0.41) but not with FIM total scale, while concurrent validity, in relation to the RLAS scale, was both strong at admission (0.60) and at discharge (0.79). Other studies found the WNSSP to correlate significantly with the Wessex Head Injury Matrix scale at r = 0.87 and the Post-Acute Level of Consciousness scale at 0.88 to 0.93 involving 29 brain-injured comatose patients aged 21 to 83 years who were followed longitudinally (Eilander et al., 2009; Schnakers, Laureys, & Majerus, 2004). Whereas, a study by Gill-Thwaites and Munday (2004) of 60 subjects diagnosed in vegetative state on admission and assessed at 2 60-day intervals found the correlation between WNSSP total score and the Sensory Modality Assessment total scores was significant at 0.70. Finally, a retrospective medical chart audit design of 38 subjects with an RLAS score between 2 and 3 showed that at admission the mean total-score WNSSP was 38 and at discharge it was 70, suggesting an ability to detect meaningful change (Allaous, McLachlan, Cusick, & Lannin, 2011).

Advantages

The WNSSP is based in part on the RLAS levels 2 to 5 and is designed to be a particularly sensitive instrument relative to levels 2 and 3 of that scale (generalized response, localized response, confused, agitated, and confused, inappropriate, non-agitated state) as well as those individuals who are slow to recover in general, thus it is considered more sensitive to change between levels 2 through 5 of the RLAS. Also, items on the WNSSP use an ordered hierarchy similar in some ways similar to that of the Wessex Head Injury Matrix scale discussed in Chapter 34, making it a unique assessment tool.

Disadvantages

The WNSSP can take up to 45 minutes to complete and requires the use of various items. The amount of peer-reviewed literature is also limited. A systematic review by Seel et al. (2010) noted poor internal consistency for some subscales (α = 0.35 to 0.59) as well as not being sensitive to change in low-functioning individuals and argue that overall, the scale’s validity remains unproven.

Administration

The WNSSP is an observational test of 33 that are items administered bedside and scored on the type of stimulation (general or specific), the latency of reaction, and need for cueing (Lannin et al., 2013). Tools needed include a handheld mirror, an object for manipulation, cologne or other olfactory stimulus, a type of “read and do what it says” card, cotton swab, spoon, comb, and a pencil, among others. Each test section has several items and includes a communication section which examines the presence of a yes/no response and the ability to vocalize or mouth words; an auditory section that rates the perception of voice and nonverbal sound and response to auditory commands; a visual response section that assesses tracking behavior and subject response to written commands; a tactile response section that judges perception of touch and the use of common objects; and finally, an olfactory response section used to rate the subject’s perception of various odors.

TABLE 35-1

EXAMPLE ITEMS OF THE WESTERN NEURO SENSORY STIMULATION PROFILE