Canadian Neurological Scale (CNS)

Evidence Reviewed as of before: 09-01-2012
Author(s): Katie Marvin, MSc. PT (Candidate)
Editor(s): Annabel McDermott, OT; Nicol Korner-Bitensky, PhD OT
Expert Reviewer: Dr. Robert Cote, MD

Purpose

The Canadian Neurological Scale (CNS) was developed as a simple tool to be used in the evaluation and monitoring of neurological status of patients with stroke in the acute phase (Cote, Hachinski, Shurvell, Norris & Wolfson, 1986).

In-Depth Review

Purpose of the measure

The Canadian Neurological Scale (CNS) was developed as a simple tool to be used in the evaluation and monitoring of neurological status of patients with stroke in the acute phase (Cote, Hachinski, Shurvell, Norris & Wolfson, 1986). The CNS evaluates 10 clinical domains, including mentation (level of conciousness, orientation and speech) and motor function (face, arm and leg).

Features of the measure

Items :

The CNS is comprised of 8-items measuring the level of consciousness, orientation, speech, motor function and facial weakness.

  • If patient is alert or drowsy: monitor with CNS (sections A1 and A2)
  • If patient is stuporous or comatose: monitor with Glasgow Coma Scale

MENTATION

Level of Consciousness

  • Alert 3.0
    Spontaneous eye opening, normal level of consciousness
  • Drowsy 1.5When stimulated verbally patient remains awake and alert but tends to doze

Orientation

  • Oriented 1.0
    1. Where are you? (City and Hospital)
    2. What is the month and year?

    Speech can be slurred but must be intelligible.

  • Disoriented 0.0Patient cannot state both place and time or cannot express answers in words or intelligible speech.

It is acceptable for patient to write answer to questions of orientation

Speech

  • Receptive deficit 0.0Ask pt. 1) to close eyes; 2) Point to ceiling; 3) Does a stone sink in water?

    If pt. does not complete the above 3, go to Section A2.

  • Expressive deficit 0.5
  • Normal Speech 1.0

Adapated from Canadian Neurological Scale Cheat Sheet by Brown, M.and Li, J available from: http://www.heartandstroke.on.ca/site/c.pvI3IeNWJwE/b.5385163/k.5CDC/HCP__Canadian_Neurological_Scale_CNS.htm

SECTION A1 – No Comprehension Deficit

Face: Ask pt. to smile:
None 0.5 No weakness – 0.5
Present 0.0 Weakness – 0.0 (Record L or R)
Arm: Proximal Ask pt. to lift arms to shoulder level and apply resistance above elbows bilaterally
None 1.5 No weakness – 1.5
Mild 1.0 Movement to 90°, unable to oppose pressure – 1.0
Significant 0.5 Movement < 90° – 0.5
Total 0.0 Absence of motion – 0.0
Arm: Distal Ask pt. to bend wrist back. Apply pressure on back of the hand.
None 1.5 No weakness – 1.5
Mild 1.0 Can bend wrist, unable to oppose pressure – 1.0
Significant 0.5 Some movement of fingers – 0.5
Total 0.0 Absence of movement – 0.0
Leg: Proximal Ask pt. to flex knee to 90°. Push down on each thigh one at a time.
None 1.5 No weakness – 1.5
Mild 1.0 Can lift leg, unable to oppose pressure – 1.0
Significant 0.5 Lateral movement but no power to lift leg – 0.5
Total 0.0 Absence of movement – 0.0
Leg: Distal Ask pt. to point toes and feet upward. Push down on each foot one at a time.
None 1.5 No weakness – 1.5
Mild 1.0 Can point foot & toes upward, unable to oppose pressure-1.0
Significant 0.5 Some movement of toes, but cannot lift toes or foot – 0.5
Total 0.0 Absence of movement – 0.0

SECTION A2 – Comprehension Deficit

Face: Ask pt. to mimic your grin (if unable, apply pressure to sternum).
Symmetrical 0.5 Symmetrical – 0.5
Asymmetrical 0.0 Asymmetrical – 0.0
Arms: Demonstrate/place pt. arms in front of pt. at 90° (if unable, apply finger nail bed pressure bilaterally and compare response)
Equal 1.5 Equal motor response – 1.5
Unequal 0.0 Unequal motor response – 0.0 (record L or R)
Legs: Thighs flexed to 90° (if unable, apply toenail bed pressure bilaterally and compare response)
Equal 1.5 Maintain position or withdraw equally – 1.5

Scoring and Score Interpretation:

  • Mentation: Comprised of evaluating consciousness, orientation and speech.
  • Motor function evaluations are separated into sections A1 and A2. A1 is administered if the patient is able to understand and follow instructions. A2 is administered in the presence of comprehension deficits (Cote et al., 1986, 1989). Each motor item is rated for severity and each rating is weighted “according to the relative importance of a particular neurological deficit” (Cote et al., 1989).
  • It should be noted that assessment using the CNS focuses on limb weakness over other possible neurological impairments (Muir, Weir, Murray, Povey & Lees, 1996).
  • The CNS scores only the motor strength of the weakest limb. For patients with a comprehension deficit, asymmetry in strength is scored. Therefore, in addition to using the CNS, clinicians may wish to further evaluate and document the upper and lower extremity strength and power in patients with comprehensive deficit (O’Farrell & Yong Zou, 2008).
  • Scores from each section are summed to provide a total score out of a possible 11.5. Lower scores are representative of increasing severity.

Nilanont et al. (2010) developed and validated a conversion model that allows clinicians and researchers to predict NIHSS scores for patients based on their CNS score in order to allow for comparability between the two scales. CNS scores can be reliably converted into NIHSS scores using the following conversion: NIHSS = 23 – (2 x CNS score).

Time:

The CNS takes approximately 5 to 10 minutes to complete (Cote et al., 1986, 1989; O’Farrell & Yong Zou, 2008).

Training requirements:

It is advised that the CNS be completed by a healthcare professional trained in its administration. The CNS does not need to be completed by a neurologist.

A trained observer rates the patent’s ability to answer questions and perform activities. Training is minimal and is available through participation in a 2-hour workshop or a self-directed learning package and review video. For more details on training requirements please visit the following website: http://www.heartandstroke.on.ca/site/c.pvI3IeNWJwE/b.5385163/k.5CDC/HCP__Canadian_Neurological_Scale_CNS.htm

Subscales:

The subscale items encompass level of consciousness, orientation, speech, motor function and facial weakness.

Equipment:

None typically reported.

Alternative forms of the assessment

None typically reported

Client suitability

Can be used with:

Patients in the acute phase of stroke who are either alert or drowsy (Cote et al., 1986).

Should not be used with:

  • As the CNS was designed as an observational scale, measurement by self-report or by telephone is not possible.

Languages of the measure

None reported.

Summary

What does the tool measure? The CNS measures neurological status.
What types of clients can the tool be used for? Patients with stroke in the acute phase who are either alert or drowsy.
Is this a screening or assessment tool? Assessment
Time to administer Approximately 5 to 10 minutes.
Versions There are no alternative versions reported.
Other Languages No information reported.
Measurement Properties
Reliability
  • One study examined the internal consistency of the CNS and reported excellent internal consistency.
  • Two studies investigated the inter-rater reliability and found adequate to excellent inter-rater reliability.
Validity
  • One study evaluated the concurrent validity of the CNS and found excellent concurrent validity between the CNS and global neurological examination.
  • Two studies evaluated the predictive validity of the CNS and found initial CNS scores to predict death within 3 to 6 months, morbidity, and recovery of ADL within 3 to 5-months.
  • One study evaluated the discriminant validity of the CNS and found excellent correlation between total CNS scores and standard neurological examinations.
Floor/Ceiling Effects Floor/ceiling effects have not yet been examined.
Does the tool detect change in patients? The CNS can be used to monitor change in neurological status in patients with acute stroke.
Acceptability The CNS is short and simple. Patient burden associated with its use should be minimal.
Feasibility A trained healthcare professional should administer the CNS. It may be used both prospectively and retrospectively.
How to obtain the tool? The CNS is available from strokecenter.org.
A full version of the measure can be found in the following article: Cote, R., Hachinski, V., Shurvell, B., Norris, J. & Wolfson, C. (1986). The Canadian Neurological Scale: A preliminary study in acute stroke. Stroke, 17(4), 731-737.

Psychometric Properties

Overview

For the purposes of this review, we conducted a literature search to identify all relevant publications on the psychometric properties of the CNS.

Floor/Ceiling Effects

Floor/ceiling effects have not yet been examined.

Reliability

Internal Consistency:
Cote et al. (1986) examined the internal consistency of the CNS in 34 patients with acute stroke. Four raters (one neurologist, one resident in neurology and two nurses) evaluated the patients. Internal consistency, as calculated using Cronbach’s alpha, was excellent for all domains (leg weakness 0.896; facial weakness 0.934; distal arm weakness 0.969; orientation 0.979; proximal arm weakness 0.98; and speech 1.00). No differences between professionals were found.

Intra-rater:
Intra-rater reliability has not been examined.

Inter-rater:
Cote et al. (1986) examined the inter-rater reliability of the CNS in 34 patients with acute stroke. Four raters (one neurologist, one resident in neurology and two nurses) evaluated the patients within two to four hours of each other using the CNS. Inter-rater reliability, as calculated using kappa statistics, was adequate to excellent for all domains (leg weakness 0.722-0.842; facial weakness 0.535-1.00; distal arm weakness 0.758-0.974; orientation 0.744-1.00; proximal arm weakness 0.788-1.00; and speech 0.934-1.00).

Brushnell, Johnston and Goldstein (2001) looked at the retrospective inter-rater reliability scoring of both the CNS and the National Institute of Health Stroke Scale (NIHSS). They compared data from academic medical centers to data from community hospitals with neurologists and community hospitals without neurologists. Inter-rater reliability for the CNS, as calculated using Intraclass correlation coefficient (ICC), was found to be excellent for all charts reviewed (academic medical center ICC=0.97; community hospital with neurologists 0.88; community hospital without neurologists 0.78). The inter-rater reliability for the NIHSS was excellent for the charts reviewed from the academic medical centre and the community hospital with a neurologist (ICC=0.93; 0.89 respectively), however only adequate agreement was found for charts reviewed from the community hospital without a neurologist (ICC=0.48). More data was missing for the NIHSS in comparison to that missing for the CNS likely due to the fact that the NIHSS requires a more detailed neurological examination. These results suggest that scoring the CNS retrospectively is reliable regardless of whether the medical record contains evaluation material from a neurologist.

Test-retest:
Test-retest reliability has not been reviewed.

Validity

Content :

Content validity has not been reviewed.

Criterion :

Concurrent:
Cote et al. (1989) evaluated the concurrent validity of the CNS in the original validation study involving 157 patients with acute stroke. Patients were evaluated by staff neurologists or neurology residents upon admission to the hospital and were classified as either having no, mild, moderate or severe deficit resulting from acute stroke. Nurses then evaluated the patients using the Glascow Coma Scale (GCS) and the CNS. An average interval of 3.71 hours occurred between assessments. Concurrent validity was evaluated by correlating CNS item with the appropriate components of the neurological examination, and the total score of the CNS with the global assessment on the neurological examination (no, mild, moderate or severe). Concurrent validity, as measured by Spearman rank correlation, was found to be excellent between the global neurological examination and the total CNS score (0.775). The concurrent validity between the neurological components and CNS was found to be excellent for orientation (0.716), speech (0.691) and weakness (0.767); and adequate for level of consciousness (0.574).

Predictive:
Cote et al. (1989) evaluated the predictive validity of the CNS in 157 patients with acute stroke. Three outcomes were evaluated: 1) death at 6 months; 2) any vascular event within 6 months (for example, MI, CVA or vascular death); and 3) independence in ADL at 5 months or beyond. Initial CNS scores were found to significantly predict death within 6 months, morbidity, and recovery of ADL within 5-months. For patients with scores of ≥ 11, only 2.1% had died at 6 months, 2.1% experienced another vascular event, approximately 90% were independent in ADLS at 5 months or beyond; compared to those that scored <9 initially where 13.2% had died at 6 months, 20.6% experienced another vascular event and <50% were independent in ADLS at 5 months or beyond.

Muir et al. (1996) compared the CNS, National Institute of Health Stroke Scale (NIHSS) and the Middle Cerebral Artery Stroke Score (MCANS) to see which scale best predicted good (alive at home) or poor (alive and requiring in care or dead) outcome at 3-months in 373 patients with acute stroke. Predictive accuracy of the variables was compared by ROC curves and stepwise logistic regression. Logistic regression showed that the NIHSS added significantly to the predictive value of all other scores. The overall accuracy for the CNS, NIHSS and MCANS as stand alone measures was adequate (0.79, 0.79 and 0.83 respectively).

Sensitivity/Specificity:

The sensitivity/specificity has not been examined.

Construct :

Convergent/Discriminant:
Cote et al. (1989) evaluated the discriminant validity of the CNS and the Glascow Coma Scale (GCS) by comparing results with a standard neurological examination. Results from the GCS and the CNS evaluation of 157 patients with acute stroke were compared with a standard neurological examination. Excellent correlation was found between the total CNS score and the standard neurological examination (r2=0.769), however only adequate correlation was found between the GCS and the standard neurological examination (r2=0.563). These results suggest that the CNS may better discriminate neurological deficit.

Known Groups:
The known groups validity has not been examined.

Responsiveness

Cote et al. (1989) evaluated the responsiveness of the CNS in 79 patients with acute stroke. The CNS was administered on admission and throughout the first 48 hours. Patients were classified as either 1) remaining stable over first 48 hours or 2) status changed over first 48 hours. A change in score ≥ 1 yielded the highest negative predictive value (0.969), with a sensitivity of 0.933 and specificity of 0.508). The results of this study suggest that the CNS can be used to monitor clinically significant differences in neurological status.

Hagen, Bugge, and Alexander (2003) examined the responsiveness of the CNS and other commonly used outcome measures in 136 patients in the early post-stroke period. The outcomes measures were administered at 1, 3 and 6 months after stroke onset. The sensitivity of the CNS to detect change from 1 to 3 months and 3 to 6 months, as calculated using Standardized Response Mean, was small (SRM=0.2860 and 0.2849 respectively). These results suggest that the CNS has some ability to detect change in patients with stroke in the subacute phase of recovery.

References

  • Bushnell, C.D., Johnston, D.C.C. & Goldstein, L. B. (2001). Retrospective assessment of the initial stroke severity: Comparison of the NIH Stroke Scale and the Canadian Neurological Scale. Stroke, 32, 656-660.
  • Cote, R., Battista, R.N., Wolfson, C., Boucher, J., Adam, J., Hachinski, V. (1989). The Canadian Neurological Scale: Validation and reliability assessment. Neurology, 39, 638-643.
  • Cote, R., Hachinski, V., Shurvell, B., Norris, J. & Wolfson, C. (1986). The Canadian Neurological Scale: A preliminary study in acute stroke. Stroke, 17(4), 731-737.
  • Cuspineda, E., Machado, C., Aubert, E., Galan, L, Liopis, F, Avila, Y. (2003). Predicting outcome in acute stroke: A comparison between QEEG and the Canadian Neurological Scale. Clinical Electroencephalography, 34(1), 1-4.
  • Muir, K.W., Weir, C.J., Murray, G.D., Povey, C., Lees, K.R. (1996). Comparison of neurological scales and scoring systems for acute stroke prognosis. Stroke, 27, 1817-1820.
  • Nilanont, Y., Komoitri, C., Saposnik, G., Cote, R., Di Legge, S., Jin, Y. et al. (2010). The Canadian Neurological Scale and the NIHSS: Development and validation of a simple conversion model. Cerebrovascular Disease, 30(2), 120-126.
  • Shinar, D., Gross, C.R., Mohr, J.P., Caplan, L.R., Price, T.R., Wolf, P.A. et al. (1985). Interobserver variability in the assessment of neurologic history and examination in the stroke data bank. Archives of Neurology, 42, 557-565.

See The Measure

How to obtain the CNS?

The CNS is available from strokecenter.org.

A full version of the measure can be found in the following article: Cote, R., Hachinski, V., Shurvell, B., Norris, J. & Wolfson, C. (1986). The Canadian Neurological Scale: A preliminary study in acute stroke. Stroke, 17(4), 731-737.

A training video has been produced by the Heart & Stroke Foundation of Canada using the Canadian Neurological Scale.

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