From hands-on to numbers
In the previous guide you sat down with the physiatric history and examination and learned to listen for what a person can and cannot do. Now we narrow in on the part of that exam where your own hands become the instrument. The challenge is blunt: hands are wonderfully sensitive, but they are private. What you feel through your palm cannot be mailed to the next clinician, charted, or compared to last week. The whole job of this guide is to take three things you assess by touch — strength, tone, and reflexes — and pin each to a small, agreed scale so that what was a feeling becomes a figure.
There is a deeper reason this matters than mere tidiness. A rehabilitation team — the physician, the physical and occupational therapists, the nurse — only works if everyone reads the same dial. If one person writes "leg is fairly strong" and another writes "weak but improving," no one can tell whether the patient gained ground. A shared, repeatable number is what lets a team set a goal on Monday and check it on Friday. This is also why the same property keeps coming up across the assessment track: a measure is only worth using if two examiners get the same answer on the same patient. That property — the psychometric properties of outcome measures — is the quiet judge sitting behind every scale below.
Grading strength: the 0–5 muscle scale
Start with strength. The bedside method is manual muscle testing: you ask a person to move one joint while you watch, then feel how much push the muscle can offer against gravity and against your hand. The genius of the scale that organizes it — the MRC grading scale, named for the council that popularized it — is that it does not start from how hard you push. It starts from gravity. A muscle that cannot even twitch is 0. A flicker with no movement is 1. Movement only when gravity is taken out of the way (sliding a limb sideways on a smooth surface) is 2. Lifting against gravity but folding the moment you add resistance is 3. The top two grades, 4 and 5, are where your hand finally comes in: 4 holds against some resistance, 5 is normal full strength.
GRADE WHAT YOU SEE / FEEL GRAVITY? 0 no contraction at all - 1 a flicker or trace of contraction, no movement no joint motion 2 full movement only with gravity eliminated moves sideways 3 full movement against gravity, none vs resistance lifts up 4 movement against gravity + some resistance (4-, 4, 4+ used) 5 normal power against full resistance full
Grading tone: Ashworth and Tardieu
Strength is what the patient does on command. Tone is different — it is the resistance you feel when you move a relaxed limb yourself, while the patient does nothing. You met the idea on the motor rung; here we measure it. The most common bedside tool is the modified Ashworth scale, the modified Ashworth scale. You move the joint through its range and grade the resistance from 0 (none) up through 1, 1+, 2, 3 to 4 (the limb is rigidly fixed). It is quick, needs no equipment, and is used the world over. But notice what it quietly assumes: that the only thing that matters is how much resistance you feel, not how fast you moved.
That assumption is the catch, because true spasticity is velocity-dependent: move the limb slowly and it may glide; move it fast and it suddenly catches and resists. The Ashworth scale, by not standardizing speed, blurs spasticity together with plain stiffness from shortened tissue — two problems with utterly different treatments. The Tardieu scale, the Tardieu scale, was built to fix exactly this. It deliberately moves the joint at two named speeds — as slow as possible, then as fast as possible — and records both the quality of the catch and, crucially, the angle at which it appears. Comparing the slow and fast angles separates the part of the tightness that is a live, speed-triggered reflex from the part that is fixed shortening of the muscle. That distinction is not academic; it decides whether the answer is botulinum toxin, stretching and casting, or surgery.
Consider a woman three months after a stroke whose elbow stays bent. On the Ashworth scale you grade a firm 2 — useful, but it does not tell you why. Done well, the Tardieu test reveals that when you move slowly her elbow opens nearly all the way, but when you move quickly it catches early and hard. That pattern says the problem is mostly a live reflex, not a frozen joint — so reducing the overactive muscle could give her elbow back. Had the slow and fast angles been the same, you would have learned the opposite: the tissue itself has shortened, and no drug that quiets a reflex will lengthen it. Same elbow, two scales, two different stories — and only one of them points at the right treatment.
Reflexes and sensation: reading the wiring
Strength and tone tell you how the muscles behave; the sensory and reflex examination tells you about the wiring that drives and feeds them. For reflexes, the examiner taps a tendon — knee, ankle, elbow — and grades the resulting jerk on a small scale, typically 0 (absent) to 4+ (very brisk, with sustained beating). You met why this works on the motor rung: a tendon tap is a quick, automatic loop through the spinal cord. The number you write down localizes trouble. A reflex that is reduced or gone points down the wiring, to the nerve or muscle. A reflex that is exaggerated, spreading, or accompanied by clonus points up, to the brain or cord above. The grade turns a tap into a clue about where the lesion sits.
Sensation is the harder half to make reproducible, because so much of it rests on what the patient reports. The examiner tests light touch, pinprick, vibration, and joint position sense, mapping where they are normal, reduced, or absent — often against a chart of the skin's nerve territories so the pattern can localize the level of injury. The trick to making this honest is structure: same body landmarks, same order, eyes closed, compared side to side, and recorded as a map rather than a vague "sensation reduced." A patchy mismatch that follows no nerve territory is itself a finding. Done loosely it is nearly worthless; done systematically it can pinpoint a spinal level to within a segment.
Making the numbers trustworthy
Here is the thread tying all of this together: a scale only helps if it is applied the same way every time. The score is not really a measurement of the patient alone — it is a measurement of patient-plus-procedure. Change the patient's position, the time of day, how rested they are, or which examiner holds the limb, and the grade can drift without the patient changing at all. A muscle graded at the end of an exhausting therapy session will test weaker than the same muscle at rest. So the discipline behind a good number is dull but decisive: standardize the conditions, then keep them fixed every time you re-measure.
- Standardize position and instruction — same posture, same words, same stabilizing hand each time, so the test, not the setup, is what varies.
- Control speed where speed matters — slow for Ashworth-style tone, deliberately slow-then-fast for the Tardieu, so a velocity-dependent catch is not missed.
- Record the exact figure and conditions — "elbow flexors 4-/5, seated, rested" beats "a bit weak," because only the first can be repeated and compared.
- Re-measure under the same conditions — change only one thing (the patient over time), so any shift in the number means something real.