Limb Ataxia Assessment on the NIH Stroke Scale
Direct Answer
Limb ataxia on the NIHSS is assessed using finger-to-nose and heel-to-shin testing, with a score of 1 indicating ataxia present in one limb that is out of proportion to any weakness, and this finding should be scored as 0 if the patient is hemiplegic or aphasic since ataxia cannot be reliably assessed in these contexts. 1
Assessment Technique
How to Perform the Test
Test finger-to-nose coordination in the upper extremities and heel-to-shin coordination in the lower extremities, specifically looking for dysmetria, intention tremor, or irregular movement patterns. 1
Score ataxia only when it is clearly out of proportion to any weakness present—if weakness alone could explain the incoordination, do not score it as ataxia. 1
Mark the item as "X" (unable to assess) if amputation, fusion, or fracture prevents testing. 1
Scoring System
The limb ataxia item uses a 0-2 scale: 1
- 0 = No ataxia present (or patient is aphasic/hemiplegic, making assessment unreliable) 1
- 1 = Ataxia present in one limb 1
- 2 = Ataxia present in two limbs 1
- X = Unable to assess due to amputation, fusion, fracture, etc. 1
Clinical Significance of Score = 1
What It Indicates
A score of 1 indicates cerebellar pathway dysfunction affecting one limb, suggesting involvement of the ipsilateral cerebellar hemisphere, superior cerebellar peduncle, or their connections. 1
This finding contributes to the overall NIHSS score and helps localize the stroke to structures involving cerebellar coordination pathways. 1
Prognostic Implications
The presence of isolated limb ataxia (score 1-2) typically indicates a lower overall NIHSS score, which correlates with better functional outcomes—scores <6 forecast good recovery. 1
Ataxia as an isolated finding generally suggests a smaller stroke volume compared to patients with dense hemiplegia. 1
Critical Assessment Pitfalls
Common Errors to Avoid
Do not score ataxia in a hemiplegic limb—the limb ataxia item specifically requires that ataxia be "out of proportion to weakness," and hemiplegia makes reliable ataxia assessment impossible. 1, 2
Do not confuse weakness-related incoordination with true cerebellar ataxia—true ataxia shows dysmetria, intention tremor, and decomposition of movement even when strength is relatively preserved. 1
Score as 0 (not X) if the patient is aphasic or hemiplegic, since these conditions preclude reliable assessment rather than representing a mechanical barrier. 1
Reliability Concerns
The limb ataxia item demonstrates lower inter-rater reliability compared to other NIHSS components, particularly when assessed via telemedicine, requiring extra attention during scoring. 1, 3
In rehabilitation settings, the limb ataxia item has been shown to fit poorly with the overall scale construct, with lower ratings paradoxically associated with higher total NIHSS scores in some analyses. 2
This item should be modified to explicitly indicate "untestable due to hemiplegia" rather than attempting to score ataxia in paralyzed limbs. 2
Management Implications
Acute Stroke Decision-Making
The NIHSS total score (including limb ataxia) guides thrombolytic therapy decisions, with scores used to stratify patients by severity and predict outcomes. 1
A change of ±4 points from baseline NIHSS (which could include changes in limb ataxia scoring) may modify eligibility for thrombolytic therapy and should trigger reassessment. 3
Localization and Workup
Isolated limb ataxia suggests posterior circulation involvement (cerebellar or brainstem stroke) and should prompt specific attention to vertebrobasilar territory on imaging. 1
The NIHSS may underestimate posterior circulation stroke severity because symptoms like vertigo and dysphagia are not included in the scale. 3
Rehabilitation Considerations
Patients with documented limb ataxia should be reassessed using the NIHSS at acute care discharge and upon transfer to rehabilitation to track recovery. 1
Cerebellar ataxia affecting limb coordination requires specialized occupational and physical therapy targeting compensatory strategies for activities of daily living. 1