Neurology Chapter 16: How do spinal cord injury levels relate to function?

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FROM MY PT SCHOOL NOTES · NEUROLOGY · UNIT 5 · CHAPTER 16

How do spinal cord injury levels relate to function?

Neurological level, injury severity and the actual examination—not vertebral labels alone—help explain the person’s motor, sensory and autonomic challenges. A useful PT assessment connects those findings to achievable activities and meaningful goals.

Build the clinical picture

Spinal cord cross-section showing gray matter horns, white matter columns, and corresponding tissue section.
Spinal cord cross-section. OpenStax Anatomy & Physiology, CC BY 4.0. Original illustration, unmodified.

Know the difference between vertebral and neurological level

The level of a vertebral fracture on imaging and the neurological level of injury (NLI) determined by standardized sensory and motor testing are not necessarily the same. Cord segments also do not line up perfectly with vertebral bodies, especially caudally. Use the medical record and a properly performed neurologic examination rather than equating a C6 fracture with C6 neurological function.

Tetraplegia describes involvement of the trunk, legs and portions of the arms due to cervical cord injury; paraplegia generally describes impairment of trunk and legs with upper-limb function relatively spared, depending on level. These terms describe broad patterns, not independence.

Relate selected motor levels to a task

For students, remember landmark functions: C5 elbow flexion, C6 wrist extension, C7 elbow extension, C8 finger flexion, T1 small-finger abduction; L2 hip flexion, L3 knee extension, L4 ankle dorsiflexion, L5 great-toe extension and S1 ankle plantarflexion. These are standard key muscle actions used in ISNCSCI, not promises that a person will gain a certain ADL or walking ability.

A cervical injury may alter hand use, arm loading, trunk control and cough/respiratory support. Thoracic and lumbar injuries may have different balance, transfer and locomotor implications. Sacral function can influence bowel/bladder and sexual health. Sensory loss may affect skin protection at any level.

Distinguish complete/incomplete from movement ability

A complete injury in ISNCSCI refers to absence of sacral sensory and motor sparing, not ‘nothing moves below the injury.’ An incomplete injury retains defined sacral sparing. Some isolated movements or sensation below the NLI can occur without making a lesion incomplete under the formal classification rules.

Patterns such as central cord, Brown-Séquard, anterior cord and conus/cauda equina injuries can help generate hypotheses. They are not perfect maps or reliable forecasts of recovery; level, etiology, secondary injury and actual function all matter.

At a glance

Cervical cordPotential arm/hand, trunk, leg and respiratory implications
Thoracic cordVariable trunk control and legs; typical upper-limb key muscles often preserved
Lumbar/sacral neural structuresVariable hip, leg, foot, bowel/bladder and pelvic function

What matters in PT?

Assess activity, sensation, respiratory readiness, skin, autonomic responses, upper-limb capacity and environmental demands. For example, intact wrist extension may permit a useful tenodesis strategy, but the person’s actual hand function and adaptive equipment needs require examination.

Clinical reasoning case

A patient has a radiology report of a C5 fracture but documented C6 key-muscle strength and patchy preserved sensation below the injury. Should you assign neurological level and AIS grade from the fracture report?

Reasoning: No. The neurological level and AIS classification require a trained ISNCSCI examination, including relevant sacral findings; functional abilities should be documented separately.

Check your understanding

Explain why vertebral level, motor level, NLI, AIS grade and transfer independence describe different things.

Original uploaded class notes: SCI Part 1.pdf; SCI Terms.pdf; 8 SCI Acute Care and Active Rehabilitation.pdf. Historical note: The uploaded epidemiology and prognosis figures are from older lectures. Compare them with your own notes and current research, including the 2026 ISNCSCI resources. These student notes are educational, not a substitute for supervised clinical assessment or emergency care.

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