Indication
- Deafferentation pain resulting from nerve root avulsion.
- Most commonly occurs in motorcycle accidents
- Brachial plexus injury
- 80–90% long-term significant improvement in pain
- Spinal cord injuries (SCI)
- Pain around the lowest spared dermatome with caudal extension of pain restricted to a few dermatomes (SCI with diffuse pain involving the entire body and limbs below the injury is less responsive)
- Pain limited to the region of injury have an 80% rate of improvement,
- Compared to 30% for those with pain involving the entire body below the lesion
- Postherpetic neuralgia:
- Usually good initial response
- But early recurrence in ≤ few months is common
- 25% have long-term relief of pain
- Postamputation phantom limb pain:
- Controversial
Generally not used for cancer pain
Technique
- Laminectomy over the involved segment(s)
- Dura is opened
- DREZ is identified under microscope magnification using intact posterior rootlets above or below for orientation
- (Contralateral rootlets may also be used to estimate the mirror-image location).
- Lesions are created ipsilateral to the avulsed nerve roots by
- Radiofrequency current
- 50–60 lesions are required for several segments, each lesion is done at 75° for ≈ 15 seconds)
- Selective incisions
- Extending from the last completely normal rootlet at the rostral end to the first normal rootlet caudally.
- The lesioning needle or knife blade is angled 30–45° medially and inserted to a depth of 2–3mm.
- DREZ lesions may be combined with a cordectomy at the level of anatomic cord disruption in paraplegic patients
- Post-op management
- Bed rest for 3 days may reduce the risk of CSF leakage.
- Analgesics appropriate for a multilevel laminectomy are administered
Complications
- Ipsilateral weakness (related to corticospinal tract) or loss of proprioception (dorsal columns) occurs in 10% of patients, and is permanent in ≈ half (i.e., 5%).
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