Definition
Transient radiation myelopathy (TRM) is a benign and temporary form of myelopathy. It is characterised by Lhermitte’s sign; the subjective complaint of unpleasant electric-shock sensation or numbness radiating down the extremities upon neck flexion.r
Pathophysiology
TRM may develop following spinal irradiation. It is attributed to temporary demyelination of the spinal cord in the irradiated segment.rrr
Incidence/prevalence
Incidence of TRM has been reported between 3.6 to 10.3% in patients who have received radiation to the head and neck region.rr
Onset/duration
Studies suggest the median development time for Lhermitte's sign is 3.0 months after the completion of RT. It typically resolves over the subsequent 3-6 months without treatment.r
Risk factors
Risk factors for developing TRM include the extent of the spinal cord included in the treatment field and the dose given per fraction e.g. there is an increased risk in patients receiving >2 Gy per fraction/per day, and those receiving bilateral neck-boost irradiation.r Concurrent chemotherapy can also increase risk of developing Lhermitte's sign.r
The development of TRM has not been shown to predict the development of chronic progressive radiation myelopathy.r