Heel-to-Shin Test: Dysmetria
The phenomenon you're describing is called dysmetria or ataxia, which refers to the inability to control the range of movement during the heel-to-shin test, causing the foot to "fall off" or slide off the shin during the maneuver.
What This Test Evaluates
The heel-to-shin test is a cerebellar function examination that assesses coordination and proprioception. When a patient cannot maintain smooth, controlled movement of the heel down the shin, this indicates cerebellar dysfunction or proprioceptive impairment.
Key Clinical Features
- Dysmetria specifically describes the inability to judge distance and control movement amplitude, causing the heel to overshoot, undershoot, or fall off the shin entirely
- Ataxia is the broader term encompassing uncoordinated movements, of which dysmetria is one manifestation
- This finding suggests pathology in the cerebellum, posterior columns of the spinal cord, or peripheral sensory nerves
Clinical Context
This neurological sign is completely distinct from traumatic foot injuries or amputations. The evidence provided regarding foot trauma, amputations, and ankle injuries 1, 2, 3, 4, 5, 6, 7, 8, 9 is not relevant to this neurological examination finding.
Differential Diagnosis for Dysmetria
- Cerebellar lesions (stroke, tumor, multiple sclerosis, alcohol toxicity)
- Posterior column disease (vitamin B12 deficiency, tabes dorsalis, spinal cord compression)
- Peripheral neuropathy with severe proprioceptive loss
- Acute intoxication (alcohol, sedatives, anticonvulsants)
Proper Test Performance
- Patient lies supine with eyes open
- Instruct patient to place heel of one foot on opposite knee
- Patient slides heel smoothly down the shin to the ankle
- Observe for smooth, controlled movement versus jerky, uncoordinated motion or the heel falling off laterally
A positive test (dysmetria) warrants immediate neurological evaluation to identify the underlying cause, as this may represent acute cerebellar stroke, demyelinating disease, or other serious neurological conditions requiring urgent intervention.