Truncal Dermatomes

The truncal dermatomes describe the sensory distribution of spinal nerve roots across the chest, abdomen and back. These dermatomes run in relatively horizontal bands around the torso, although the precise boundaries vary between individuals and neighbouring nerve roots overlap.

Pain arising from irritation of a thoracic spinal nerve root may therefore feel quite different from ordinary muscular or joint pain. Patients may describe burning, stabbing, tingling, hypersensitivity or electric-shock-like pain travelling around one side of the chest or abdomen. Sometimes even light clothing or gentle touch can become uncomfortable. Because the pain may follow a band-like or belt-like distribution, patients can sometimes mistake it for a problem involving the ribs, muscles or internal organs.

There are several possible causes of truncal neuropathic or radicular pain. These can include degenerative changes in the spine, disc disease, narrowing around a nerve root, inflammation and, in some cases, herpes zoster (shingles). Persistent nerve pain can occasionally remain after the skin eruption of shingles has resolved. Because chest and abdominal pain can also arise from non-spinal conditions, new or unexplained truncal pain should be medically assessed rather than assumed to be a spinal nerve problem.

Assessment involves considering the location and quality of pain, sensory changes, neurological findings and the relationship of symptoms to the relevant spinal level. When appropriate, imaging may be used to investigate structural causes.

Treatment is directed at the underlying cause and may include medication, physical rehabilitation and targeted pain-management procedures. In selected patients where a specific spinal nerve root or dorsal root ganglion is believed to be contributing to persistent neuropathic pain, procedures such as a Dorsal Root Ganglion Block may be considered for diagnostic and/or therapeutic purposes. In appropriately selected cases, Dorsal Root Ganglion Pulsed Radiofrequency may also be considered as part of a multidisciplinary pain-management approach. An Epidural Steroid Injection may be appropriate in selected patients where inflammation around the spinal nerve roots is contributing to radicular symptoms.

Importantly, not every band-like pain around the chest or abdomen is caused by a spinal nerve. A careful medical assessment is essential, particularly when symptoms are new, severe or associated with other concerning symptoms.