Canadian Neurological Scale (CNS)

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 1.5
    When 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 0.0
    Patient 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 0.0
    Ask 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:

None 0.5

Present 0.0

Ask pt. to smile:

No weakness – 0.5

Weakness – 0.0 (Record L or R)

Arm:
Proximal

None 1.5

Mild 1.0

Significant 0.5

Total 0.0

Ask pt. to lift arms to shoulder level and apply resistance above elbows bilaterally

No weakness – 1.5

Movement to 90°, unable to oppose pressure – 1.0

Movement < 90° – 0.5

Absence of motion – 0.0

Arm:
Distal

None 1.5

Mild 1.0

Significant 0.5

Total 0.0

Ask pt. to bend wrist back. Apply pressure on back of the hand.

No weakness – 1.5

Can bend wrist, unable to oppose pressure – 1.0

Some movement of fingers – 0.5

Absence of movement – 0.0

Leg:
Proximal

None 1.5

Mild 1.0

Significant 0.5

Total 0.0

Ask pt. to flex knee to 90°. Push down on each thigh one at a time.

No weakness – 1.5

Can lift leg, unable to oppose pressure – 1.0

Lateral movement but no power to lift leg – 0.5

Absence of movement – 0.0

Leg:
Distal

None 1.5

Mild 1.0

Significant 0.5

Total 0.0

Ask pt. to point toes and feet upward. Push down on each foot one at a time.

No weakness – 1.5

Can point foot & toes upward, unable to oppose pressure-1.0

Some movement of toes, but cannot lift toes or foot – 0.5

Absence of movement – 0.0

SECTION A2 – Comprehension Deficit

Face:

Symmetrical 0.5

Asymmetrical 0.0

Ask pt. to mimic your grin (if unable, apply pressure to sternum).

Symmetrical – 0.5

Asymmetrical – 0.0

Arms:

Equal 1.5

Unequal 0.0

Demonstrate/place pt. arms in front of pt. at 90° (if unable, apply finger nail bed pressure bilaterally and compare response)

Equal motor response – 1.5

Unequal motor response – 0.0 (record L or R)

Legs:

Equal 1.5

Unequal 0.0

Thighs flexed to 90° (if unable, apply toenail bed pressure bilaterally and compare response)

Maintain position or withdraw equally – 1.5

Cannot maintain position or unequal withdrawing – 0.0 (record L or R)

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.