Commissural myelotomy
- General information
- AKA mediolongitudinal myelotomy.
- Interrupts pain fibers crossing in the anterior commissure on their way to the lateral spinothalamic tract.
- Indications
- Bilateral or midline pain,
- Primarily below the thoracic levels (including abdomen, pelvis, perineum and lower extremities).
Technique
- Laminectomy must extend at least 3 levels above the highest dermatome involved in pain.
- The dura is opened longitudinally and the operating microscope is then used to identify the midline sulcus
- Veins in the midline are sacrificed for the length of the proposed incision.
- A number 11 scalpel blade is then placed in a hemostat with 6–7mm of the tip exposed.
- The blade is inserted in the midline at the upper end of the desired incision and is then passed caudally for the length of the planned incision (usually 3–4 cm).
Outcome
- 60% of patients have complete pain relief, 28% have partial, and 8% have none.
Complications
- Weakness in the lower extremities (8%)
- Usually lower motor neuron,
- Due to injury to anterior horn motor neurons
- Dysesthesias
- Occur in almost all patients,
- Persist for a few days in ≈ 16% (these patients also have impaired joint position sense, all of which are presumably due to posterior column injury).
- Bladder dysfunction (12%)
- Sexual dysfunction may also occur.
- Risk of injury to the anterior spinal artery (rare)
Punctate midline myelotomy
- Indications
- Pelvic and visceral pain refractory to other therapies.
- Technique
- Interruption of a midline posterior column pathway.
Reference
Cordotomy | Myelotomy |
Short Transverse cut | Long Longitudinal cut |
Disrupts ascending fibres | Disrupts crossing fibers |
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