What is the step‑by‑step approach to examine a patient for cerebellar dysfunction from the head down to the toes?

Systematic Head-to-Toe Cerebellar Examination

Examine cerebellar function systematically from head to toe by assessing eye movements first, then speech, upper limb coordination, truncal stability, and finally lower limb coordination and gait—documenting dysmetria, dysdiadochokinesia, truncal instability, dysarthria, and nystagmus that persist regardless of visual input. 1

Eye Movements (Cranial)

• Assess for nystagmus by having the patient follow your finger horizontally and vertically, looking for spontaneous nystagmus that persists without provocative maneuvers 2
• Test for ocular dysmetria (saccadic overshooting) by asking the patient to rapidly shift gaze between two targets 1
• Check for ophthalmoplegia if Miller Fisher syndrome is suspected (triad of ataxia, areflexia, and ophthalmoplegia) 1
• Look for downbeating nystagmus without torsional component, which suggests central cerebellar pathology rather than peripheral vestibular disease 2

Speech and Swallowing

• Evaluate for dysarthria by having the patient repeat phrases like "British Constitution" or "baby hippopotamus," listening for scanning or ataxic speech patterns with irregular rhythm and volume 1
• Assess articulation by having the patient read a list of words, noting slurred or unintelligible speech 3

Upper Limb Coordination

• Perform finger-to-nose testing by asking the patient to touch their nose then your finger repeatedly, observing for dysmetria (overshooting or undershooting the target) 1
• Test dysdiadochokinesia by having the patient rapidly alternate pronation and supination of the hands, noting irregular rhythm, amplitude, or speed 1, 4
• Assess rhythmic tapping by asking the patient to tap their index finger on their thumb rapidly and regularly, which correlates strongly with ataxia severity 4
• Evaluate ballistic tracking by having the patient rapidly move between two targets, as this combined with rhythmic tapping provides the best correlation with ataxia severity (Spearman 0.8; p < 0.001) 4

Truncal Stability

• Observe sitting posture for truncal ataxia and titubation (rhythmic swaying), which particularly indicates midline cerebellar vermian pathology 1, 2
• Test truncal stability by gently pushing the patient's shoulders while seated, noting difficulty maintaining upright posture 1
• Perform Romberg test with eyes open then closed—cerebellar ataxia does NOT worsen significantly with eye closure, distinguishing it from sensory ataxia 1, 2, 5

Lower Limb Coordination

• Perform heel-to-shin testing by having the patient slide their heel down the opposite shin from knee to ankle, observing for dysmetria and irregular trajectory 3, 1
• Assess rhythmic foot tapping by having the patient tap their foot rapidly on the ground, noting irregularity in rhythm or amplitude 4

Gait Assessment

• Observe normal gait for wide-based stance, irregular step length, and lateral veering that persists with eyes open or closed 1, 2
• Test tandem gait by having the patient walk heel-to-toe in a straight line, which amplifies cerebellar ataxia 2
• Document fall risk, which is significantly increased in cerebellar disorders and directly impacts morbidity 2

Critical Distinguishing Features

• Confirm symptoms persist with eyes open AND closed—this is the key feature distinguishing cerebellar from sensory ataxia 1, 2, 5
• Document dyssynergia (loss of coordinated multi-joint movements) during complex motor tasks 1

Associated Findings to Document

• Check pupils for abnormalities suggesting drug/toxin ingestion versus third nerve compression 1
• Assess neck for torticollis or resistance to motion indicating craniocervical junction pathology or posterior fossa tumor 1
• Examine skin for telangiectasias suggesting ataxia-telangiectasia 1
• Test reflexes for areflexia, which combined with ataxia and ophthalmoplegia indicates Miller Fisher syndrome 1

Common Pitfalls to Avoid

• Do not mistake weakness or hypotonia for ataxia—these require different diagnostic approaches 1
• Do not miss "pseudoataxia" from functional disorders that can mimic organic cerebellar disease 1
• Do not confuse vestibular dysfunction (lurching gait triggered by head rotation) with cerebellar ataxia 1
• Do not overlook spinal cord signs (motor spasticity, sensory ataxia) that would warrant spine imaging in addition to brain imaging 3, 1

Red Flags Requiring Urgent Imaging

• Sudden onset with dysarthria, dysphagia, or sensory/motor deficits suggests posterior circulation stroke 2
• Headache with truncal ataxia suggests acute cerebellitis 1
• Altered consciousness may indicate increased intracranial pressure or herniation 1
• Obtain MRI head without contrast immediately for acute presentations, as it detects abnormalities in 64% of cases and is superior to CT 5