mise à jour du
13 mai 2004
Heart Lung
1988; 18; 2; 121-129
Clinical neurologic assessment tool: development and testing of an instrument to index neurologic status
Crosby L, Parsons LC
University of Arizona, USA


The clinical neurologic assessment tool (CNA) is a 21-item instrument assessing response to verbal and tactile stimulation, ability to follow commands, muscle tone, body position, movement, chewing, and yawning in the patient with head trauma. The CNA was developed to detect subtle changes in the patients' neurologic status that may indicate transitions in the comatose state. The CNA has been extensively pilot tested. Reliability determined by using Cronbach's alpha revealed an internal consistency of 0.96. Concurrent validity testing with the Glasgow Coma Scale indicated a strong positive correlation, r = 0.94. Construct validity was assessed with factor analysis using 0.50 for a loading criterion. Three factors were demonstrated: general level of consciousness, muscle tone and resistance, and chewing or yawning. Discriminant function analysis revealed that the CNA scores correctly classified 95.1% of the patient observations into their respective Glasgow Coma Scale categories. The CNA is reliable, valid, convenient, and easily scored and captures the subtle changes in the patient with head trauma.
The annual incidence of head injuries, estimated to be 200 per 100,000 population, demonstrates a health problem that clinicians frequently encounter in a variety of settings. The detection of early warning signs of complications from head injuries can make a difference between death or disability and intact neurologic functioning. Serial assessment is necessary to detect symptoms of neurologic deterioration because treatment within 30 to 120 minutes of deterioration can make a difference in the patient's prognosis .
The Glasgow Coma Scale (GCS), because of its simplicity, consistency, and degree of interrater reliability, is a well accepted and highly utilized instrument for assessing neurologic status in a patient with head injury. The GCS has demonstrated predictive validity in the correlation between a patient's 24-hour postinjury score and eventual neurologic outcome? Despite the frequent use of the GCS, clinicians complain that the scale lacks the ability to assess subtle changes in the patient's neurologic status. Such changes may occur as the patient's level of consciousness improves or deteriorates. For example, within the GCS range of 8 to 15, evaluating a person's leve of cognition and orientation as well as ability to speak may seem critical, yet the GCS addresses only speaking ability. In one study, 38% of 451 patients with head trauma could not be evaluated by one or more components of the GCS. The use of the GCS is most difficult with patients who have endotracheal tubes in place, patients who have periorbital edema, and patients who have immobilized upper extremities. The presence of any one of these factors may encourage the person conducting the assessment to label the corresponding GCS component as untestable. The omission of valuable data on an instrument that has only three testable items may limit the instrument's clinical usefulness.
The clinical experiences of the investigators supported the assumption that a change in a patient's neurologic status was not always accompanied by a change in the patient's GCS score. Colleagues also expressed concern that several patient behaviors were not included in the GCS, such as showing signs of recognition through facial expression, following the nurse or family members with his or her eyes, and chewing or yawning.
The purpose of this article is to discuss the development of a clinical neurologic assessment tool (CNA) that may prove to be more sensitive to subtle changes in level of consciousness, thus providing earlier detection of neurologic deterioration or improvement. The CNA is a valuable tool to use throughout the hospitalization and is applicable regardless of the patients GCS score. For example, the CNA is especially suitable for assessing subtle changes in the comatose patient as the patient emerges from coma. At the other extreme, the CNA is able to more completely evaluate patients with a GCS score in the 13 to 15 range because degree of a patient's orientation is evaluated separately from the patient's ability to communicate. Overall, the instrument evaluates a patient's ability to perform verbal, motor, and cognitive functions. In addition, observations are made of the patient's body position, muscle tone, and the occurrence of spontaneous chewing and yawning (see appendix). [...]
SUMMARY The CNA is a valid and reflable instrument consisting of 21 items for measuring level of consciousness among patients with severe (GCS 3to 8), moderate (GCS 9 to 12), and mild (GCS 13 to 15) head injury. Cronbach alpha reliability coefficients for the CNA with GCS scores 3 to 8, 9 to 12, and 13 to 15 samples were 0.85, 0.83, and 0.87, respectively (Table 1). The inclusion of items to evaluate the patient's ability to communicate separately from the patient's degree of orientation provides greater descriptive data of patients who have a minor neurologic deficit. Statistically, minor neurologic injuries constitute the vast majority (49%) of patient with CNS trauma. General voluntary body movement (item 16) serves as the best indicator of level of consciousness whereas spontaneous verbalization (item 20) is the strongest predictor variable in classifying subject acuity. Ease of administration, clinical applicability, and degree of comprehensiveness arc characteristics supporting the use of the CNA in assessing patients' level of consciousness.
VI. Assessment of patient's chewing, yawning, verbalization
18. Chewing 1. Absent 2. Nonpurposeful 3. Grinds teeth 4. Normal-purposeful
19. Yawning 1. Absent 2. Present
If chewing and yawning are not observed, consult with person caring for patient. If no one has observed chewing or yawning, mark absent.
20. Verbalization 1. Unconscious/no sound 2. Moaning and/or babbling 3. Conscious/no attempts et speech 4. Single-word answers/nodding or shaking head
Physiology of yawning and its application to postoperative care
Bartlett Rh et al
Surgical Forum
1970; 21; 222-223
The yawn maneuver: prevention and treatment of postoperative pulmonary complications
Bartlett RH et al
Surgical Forum
1971, 22,196-198
Neurological assessment of coma (pdf)
David E Bateman
J Neurol Neurosurg Psychiatry
2001; 71 (suppl I); i13Ði17
Persistent vegetative state Modi M