Tuning Forks in Neurology: Understanding Their Role in Neurological Exams

Tuning forks (typically 128 Hz for vibration, 512 Hz for hearing) are simple, non-invasive tools to assess vibration sense, hearing, and cortical sensory integration.

Key Tests

1. Vibration Sense (Pallesthesia):
   • Place vibrating 128 Hz fork on bony prominence (distal interphalangeal joint, medial malleolus, tibial tuberosity, sternum).
   • Patient reports when vibration stops. Compare sides and proximal vs. distal.
   • Loss: Peripheral neuropathy (diabetes, B12 deficiency), dorsal column lesion, nerve root compression.
2. Rinne Test (Air vs. Bone Conduction):
   • Fork on mastoid (bone) → then near ear canal (air).
   • Normal: Air conduction > Bone conduction (AC > BC).
   • Conductive loss: BC > AC (negative Rinne).
   • Sensorineural loss: AC > BC but both reduced.
3. Weber Test (Lateralization):
   • Fork on midline skull (vertex/forehead).
   • Normal: Heard equally.
   • Conductive loss: Lateralizes to affected ear.
   • Sensorineural loss: Lateralizes to better ear.

Not Standard Neurological Tests (Misattributed)

• Finger-to-nose, Romberg, heel-to-toe, hopping are cerebellar/gait/coordination tests — performed without tuning fork.

Conditions Assessed

• Peripheral neuropathy (diabetic, alcoholic, hereditary)
• Dorsal column disease (B12 deficiency, MS, tabes dorsalis)
• Hearing loss (conductive vs. sensorineural)
• Radiculopathy (vibration loss in dermatome)

Tuning forks are bedside, quantitative, reproducible—cornerstones of the sensory exam.