Lhermitte's sign: incidence and treatment variables influencing risk after irradiation of the cervical spinal cord.

PURPOSE

Lhermitte's sign is a relatively infrequent sequela of irradiation of the cervical spinal cord. In this study, we sought to determine whether various treatment parameters influenced the likelihood of developing Lhermitte's sign.

METHODS AND MATERIALS

Between October 1964 and December 1987, 2901 patients with malignancies of the upper respiratory tract were treated at the University of Florida. The dose of radiation to the cervical spinal cord was calculated for those patients who had a minimum 1-year follow-up. A total of 1112 patients who received a minimum of 3000 cGy to at least 2 cm of cervical spinal cord were included in this analysis.

RESULTS

Forty patients (3.6%) developed Lhermitte's sign. The mean time to development of Lhermitte's sign after irradiation was 3 months, and the mean duration of symptoms was 6 months. No patient with Lhermitte's sign developed transverse myelitis. Several variables were examined in a univariate analysis, including total dose to the cervical spinal cord, length of cervical spinal cord irradiated, dose per fraction, continuous-course compared with split-course radiotherapy, and once-daily compared with twice-daily irradiation. Only two variables proved to be significant. Six (8%) of 75 patients who received > or = 5000 cGy to the cervical spinal cord developed Lhermitte's sign compared with 34 (3.3%) of 1037 patients who received < 5000 cGy (p = .04). For patients treated with once-daily fractionation, 28 (3.4%) of 821 patients who received < 200 cGy per fraction developed Lhermitte's sign compared with 6 (10%) of 58 patients who received > or = 200 cGy (p = .02).

CONCLUSION

An increased risk of developing Lhermitte's sign was demonstrated for patients who received either > or = 200 cGy per fraction (one fraction per day) or > or = 5000 cGy total dose to the cervical spinal cord.