Babinski Sign (Plantar Reflex)

Etiology

Babinski Sign (Plantar Reflex) Occurs with an Upper Motor Neuron Lesion Anywhere Along the Pyramidal (Corticospinal) Tract from the Motor Strip Down to Approximately L4
- The Upper Motor Neuron Lesion Results in a Loss of Inhibition

Cervical Spinal Myelopathy
Spinal Cord Injury (SCI) (see Acute Spinal Cord Injury)
- General Comments
  - Babinski Sign May Initially Be Absent During Acute Spinal Shock

Amyotrophic Lateral Sclerosis (ALS) (see Amyotrophic Lateral Sclerosis)
- Physiology
  - Motor Neuron Disease
Epidural Hematoma (see Epidural Hematoma)
Hemiplegic Migraine (see Migraines)
Hydranencephaly
Motor Strip or Internal Capsule Lesions (Cerebrovascular Accident, Tumor, Contusion, etc)
Posterior Reversible Encephalopathy Syndrome (PRES) (see Posterior Reversible Encephalopathy Syndrome)
Seizures (see Seizures)
Subdural Hematoma (see Subdural Hematoma)
Toxic-Metabolic Coma (see Obtundation-Coma)
Transient Ischemic Attack (TIA) (see Transient Ischemic Attack)
Traumatic Brain Injury (TBI) (see Traumatic Brain Injury)

Afferent Limb of the Reflex
- Originates from the Cutaneous Receptors in First Sacral Dermatome (S1) and Travels Proximally Via the Tibial Nerve
Spinal Cord Segments Involved in the Reflex Arc
- L4-S2
Efferent Limb of the Reflex
- Toe Extensors Travel Via the Peroneal Nerve

Optimal Stimulus Consists of Stimulation of the Lateral Plantar Surface and Transverse Arch in a Single Movement Lasting 5-6 Seconds
Other Means for Applying Noxious stimuli May Also Elicit the Babinski Sign (Plantar Reflex) (Even Outside the S1 Dermatome, Although These Do Not Produce Toe Flexion in Normal Patients)
- Described Maneuvers
  - Chaddock Maneuver: scratch the lateral foot
    - Chaddock Maneuver is Positive in 3% of Cases in Where Plantar Stimulation was Negative
  - Schaeffer Maneuver: pinch the Achilles tendon
  - Oppenheim Maneuver: slide knuckles down shin
  - Gordon Maneuver: momentarily squeeze lower gastrocnemius
  - Bing Maneuver: light pinpricks on dorsolateral foot
  - Gonda or Stronsky Maneuver: pull the 4th or 5th toe down and out and allow it to snap back

The Small Toes May Fan, But This is Not Consistent or Clinically Important
Babinski Sign (Plantar Reflex is Present in Infancy and Normally Disappears by Approximately 10 Months of Age (Range: 6 Months-12 y/o)
- Disappearance of the Babinski Sign (Plantar Reflex) with Infant Age is Presumably Due to Inhibitory Control as Myelination of the Central Nervous System Occurs
  - Normal Response Then Becomes Plantarflexion of the Great Toe

Triple Flexor Response is Characterized by Exaggerated Flexor Synergy Resulting in Dorsiflexion of the Ankle, Flexion of the Knee and Hip
- Similarly Due to an Upper Motor Neuron Lesion, the Triple Flexor Response May Occur in Conjunction with the Babinski Sign (Plantar Reflex)

Hoffman’s Sign May Signify an Upper Motor Neuron Interruption to the Upper Extremities
- Hoffman’s Sign Differs from the Babinski Sign (Plantar Reflex) Because it is Monosynaptic
  - Synapsed in Rexed Lamina IX
- When Hoffman’s Sign is Present Pathologically, it Represents Disinhibition of a C8 Reflex
  - Therefore, it Indicates the Presence of a Lesion Above C8
- Hoffman’s Sign Has Been Observed in 68% of Patients Operated for Cervical Spondylotic Myelopathy
- In 11 Patients Presenting with Lumbar Symptoms But No Myelopathy, a Bilateral Hoffman’s Sign was Associated with Occult Cord Compression in 91% of Cases
Technique
- Flick Downward on the Nail of the Middle or Ring Finger
  - Positive (Pathologic) Response Consists of Involuntary Flexion of the Adjacent Fingers and/or Thumb
  - May Be Weakly Present in Normal Patients
  - Can Sometimes Be Observed as Normal in Young Patients with Diffusely Brisk Reflexes and Positive Jaw Jerk (Usually Symmetric)