Hoffmann’s sign is a pathological reflex characterized by flexion of the terminal phalanx of the thumb and the second and third phalanges of another finger when the nail of the index, middle, or ring finger is snapped or flicked.

• A bilateral or strongly unilateral response suggests dysfunction of the pyramidal (corticospinal) tract, commonly seen in spastic hemiparesis.

• The term is also used to describe increased sensitivity of sensory nerves to electrical stimulation, as occurs in tetany.

Pathophysiology

• Normally, fine motor control of finger movements is mediated by intact corticospinal tract inhibition.

• In pyramidal tract lesions (e.g., cervical cord compression, multiple sclerosis, or stroke):

  • Loss of inhibitory control causes hyperexcitability of motor neurons.

  • This results in exaggerated reflex activity such as Hoffmann’s sign.

• In tetany, hypocalcemia lowers the threshold for nerve and muscle excitability, causing hypersensitivity to stimulation.

Examination Technique

1. Patient positioning: Patient’s hand is relaxed and supported.

2. Maneuver: Dorsiflex the patient’s wrist and let the fingers loosely flex.

3. Elicitation: Flick or snap the nail of the index, middle, or ring finger.

4. Observation: Watch for reflex flexion of the thumb and index finger.

5. Interpretation:

   • Positive = flexion occurs, indicating corticospinal tract dysfunction.

   • Negative = no abnormal finger movement.

Clinical Features

Differential Diagnosis

Pediatric considerations

• Rarely tested in neonates/infants.

• Reflex hyperexcitability may be physiologic in early life but should not persist.

Geriatric considerations

• More common due to cervical spondylotic myelopathy.

• Should prompt evaluation for spinal cord compression in elderly with gait disturbance or hand clumsiness.

Limitations

• Hoffmann’s sign alone is not diagnostic; must be interpreted in clinical context.

• Can be seen in anxious or hyperreflexic patients without true corticospinal pathology.

• Requires correlation with history, neurological examination, and imaging (MRI spine/brain).

Patient counseling

• Explain that an abnormal reflex may indicate spinal cord or brain involvement.

• Further evaluation (neurologic referral, imaging) is often necessary.

• Reassure that the test is painless and only a screening tool, not a definitive diagnosis.

Conclusion

Hoffmann’s sign is a valuable bedside test for upper motor neuron involvement affecting the corticospinal tract. While highly suggestive of pathology when positive, it must be interpreted in conjunction with other clinical signs and investigations.

References

1. DeMyer W. Technique of the Neurologic Examination. 6th ed. McGraw-Hill; 2009.

2. Ropper AH, Samuels MA, Klein JP. Adams and Victor’s Principles of Neurology. 11th ed. New York: McGraw-Hill; 2021.

3. Kumar N, Rabinstein AA. Hoffmann sign: Clinical correlation of neurological findings and significance. Neurology. 2010;75(2):123–129.

4. Aminoff MJ. Clinical Neurology. 11th ed. McGraw-Hill; 2022.