Complex regional pain syndrome confined to one foot

Burning pain confined to the right foot across its dorsal, lateral and plantar surfaces in the right L5 and S1 distributions, with colour and temperature changes, swelling, and allodynia to light touch. Baseline pain 9/10. The patient slept with the affected foot outside the covers year-round.

Walking was limited to short distances in a loose sandal. Closed shoes had been impossible for eighteen months. Careful sensory mapping showed that the painful region crossed the right L5 and S1 territories while remaining confined to one foot.

L3–L5 lumbar fusion with instrumentation, complicated by intraoperative injury to the right L5 and S1 nerves. Residual neuropathic pain progressed to CRPS of the right foot in those distributions.

Sympathetic blocks with brief relief, physical therapy limited by allodynia, mirror therapy, gabapentin, amitriptyline and topical agents. A spinal cord stimulator trial at another centre produced good calf coverage but almost none over the foot, and was abandoned.

The foot sits at the distal end of overlapping dermatomal territories that conventional dorsal column stimulation reaches inconsistently — a known limitation, and one this patient had already experienced directly. The distribution here included dorsal, lateral and plantar regions rather than one narrow strip of the foot.

Targeting the right L5 and S1 dorsal root ganglia created complementary fields across those adjacent territories. The two-lead plan was selected to reduce the chance of leaving a painful gap while retaining the focal, posture-stable coverage that makes DRG stimulation useful for CRPS confined to a foot.

The dorsal root ganglion sits in the foraminal space with very little cerebrospinal fluid around it, allowing defined coverage that remains comparatively stable when the patient changes position. The ACCURATE trial specifically studied lower-limb CRPS and reported higher treatment success with DRG stimulation than with conventional SCS.

Psychological evaluation completed, as it is for every implant candidate — not to screen the patient out, but to identify untreated depression, unrealistic expectations or an unmanaged sleep problem that would blunt the result. In this case it identified a treatable anxiety disorder that was addressed before implantation.

A detailed pain map was documented before the trial and used to plan two right-sided targets: L5 for the dorsum of the foot and S1 for the lateral and plantar regions. Insurance authorisation was obtained with documentation of failed conservative care and the prior unsuccessful SCS trial.