Pyramidal Tract Signs – Causes & Meaning

What Are Pyramidal Tract Signs?

Pyramidal tract signs (also called upper motor neuron signs) are a group of neurological reflex findings observed during clinical examination. They indicate damage to the pyramidal tract (corticospinal tract), the primary motor pathway connecting the cerebral cortex to the spinal cord. This pathway controls voluntary movement and regulates certain reflexes through inhibitory interneurons.

When the pyramidal tract is damaged, these inhibitory mechanisms are lost, resulting in characteristic pathological reflex responses known as pyramidal tract signs. They are a core component of the neurological examination and provide critical clues to conditions such as stroke, multiple sclerosis, brain or spinal cord tumors, and spinal cord injury.

The Pyramidal Tract – Basics

The pyramidal tract (Latin: tractus corticospinalis) is a bundle of nerve fibers originating from the motor cortex of the brain that extends down to the anterior horn cells of the spinal cord. It is essential for executing precise voluntary movements, particularly of the hands and feet. It also exerts inhibitory control over certain spinal reflexes via interneurons.

When the pyramidal tract is disrupted by disease or injury, this inhibitory control is removed and pathological reflexes emerge, which are collectively referred to as pyramidal tract signs.

Key Pyramidal Tract Signs

Babinski Sign

The Babinski sign is the most well-known and clinically significant pyramidal tract sign. It is elicited by stroking the lateral sole of the foot with a blunt instrument. In pyramidal tract damage, the response is dorsiflexion (upward extension) of the big toe, often accompanied by fanning of the other toes. In healthy adults, the normal response is plantar flexion (downward curling) of the toes. In infants up to approximately 18 months of age, a positive Babinski sign is a normal finding.

Gordon Sign

The Gordon sign is elicited by firmly squeezing the calf muscle. A positive response consists of dorsiflexion of the big toe and indicates pyramidal tract dysfunction.

Oppenheim Sign

The Oppenheim sign is elicited by applying firm pressure along the medial tibial crest (shinbone) with the thumb and index finger. A positive result is dorsiflexion of the big toe, equivalent to the Babinski sign.

Chaddock Sign

The Chaddock sign is elicited by stroking the skin below the lateral malleolus (outer ankle). A positive result – dorsiflexion of the big toe – is considered a Babinski equivalent and indicates pyramidal tract damage.

Hoffmann Sign

The Hoffmann sign is a pyramidal tract sign of the upper limb. It is elicited by flicking the fingernail of the middle finger downward. A positive response consists of flexion of the thumb and index finger of the same hand, indicating damage to the pyramidal tract at the level of the cervical spine or brain.

Troemner Sign

The Troemner sign is a variant of the Hoffmann sign: tapping the fingertips produces flexion of the thumb and other fingers in a positive response, indicating upper motor neuron dysfunction.

Hyperreflexia and Clonus

In addition to pathological reflexes, exaggerated deep tendon reflexes (e.g., hyperactive patellar or Achilles tendon reflexes) and clonus (rhythmic, involuntary muscle contractions in response to sustained stretch) are also signs of pyramidal tract damage.

Causes of Pyramidal Tract Damage

Pyramidal tract signs can result from various diseases affecting the brain or spinal cord:

• Stroke (ischemic or hemorrhagic)
• Multiple sclerosis
• Brain and spinal cord tumors
• Traumatic brain or spinal cord injury
• Amyotrophic lateral sclerosis (ALS)
• Inflammatory conditions (e.g., encephalitis, myelitis)
• Cervical myelopathy (spinal cord compression due to disc herniation or spinal canal stenosis)

Diagnosis and Clinical Relevance

Pyramidal tract signs are assessed as part of the neurological examination. A positive finding indicates damage to the first motor neuron (upper motor neuron). They are typically interpreted together with other findings such as spasticity (increased muscle tone), paresis (weakness or paralysis), and absent or reduced abdominal reflexes.

Further diagnostic workup may include imaging studies such as MRI (magnetic resonance imaging) or CT (computed tomography) of the brain and spinal cord, as well as electrophysiological tests such as MEPs (motor evoked potentials).

Treatment

The management of pyramidal tract signs is always directed at the underlying condition, as these signs are symptoms of a disease rather than a disease itself. Depending on the cause, the following treatment options may be considered:

• Stroke: thrombolysis, thrombectomy, neurorehabilitation
• Multiple sclerosis: immunomodulatory therapy, corticosteroids for relapses
• Tumors: surgery, radiation therapy, chemotherapy
• Spasticity: physiotherapy, muscle relaxants (e.g., baclofen, botulinum toxin)
• Cervical myelopathy: conservative or surgical treatment depending on severity

References

1. Duus' Topical Diagnosis in Neurology: Anatomy, Physiology, Signs, Symptoms. Baehr M, Frotscher M. Thieme Publishers, 5th edition, 2012.
2. Kandel ER, Schwartz JH, Jessell TM et al.: Principles of Neural Science. McGraw-Hill, 5th edition, 2013.
3. National Institute of Neurological Disorders and Stroke (NINDS): Motor Neuron Diseases Fact Sheet. Available at: www.ninds.nih.gov