Determination of Segment Affected in Spinal Cord Lesions

1. Big picture

When a patient has a spinal cord lesion, the examiner must answer three questions:

1. Is this really a spinal cord lesion?

2. At which spinal segment is the lesion?

3. Is it complete, hemisection, central, anterior, posterior, or compressive?

This topic is mainly about clinical localization. In the exam, they expect you to use:

• sensory level,

• motor weakness pattern,

• reflex changes,

• pyramidal signs,

• segmental lower motor neuron signs,

• autonomic bladder/bowel symptoms,

• dermatomes and myotomes.

The most important rule is:

A spinal cord lesion gives segmental signs at the level of the lesion and long-tract signs below the lesion.

So you localize the segment by combining:

• at-level signs: radicular pain, segmental sensory loss, lower motor neuron weakness, lost reflex at that segment;

• below-level signs: spastic paresis, hyperreflexia, Babinski sign, sensory level, bladder/bowel dysfunction.