Guidelines for Complications of Cancer Treatment Vol VIII Part B

probably secondary to damage to the cervical spinal cordresulting in demyelination. The clinical latency periodcorresponded to the normal survival of the myelin, sincedamaged oligodendrocytes are not capable of carrying outmyelin synthesis. As the oligodendrocytes recover, myelinsynthesis is resumed and the resolved disease does not return.Time Course of Events: This may present after 1 to 6 monthsof radiation therapy and in almost all the patients uneventfullysubsides in next 2 to 6 months.Dose/Time/Volume: In series of head and neck patients, FeinDA et al. 7 found that a global incidence of 3.6% (40 cases outof a group of 1112 patients receiving 30 Gy or more). Thedose incidence relationship is listed in the table. The risk wasalso increased with a fraction size over 2 Gy.Dose (Gy) Incidence (%)30 to 39.9 240 to 44.9 445 to 49.9 350 or more 8Chemical/Biologic Modifiers: Concomitant use of intrathecaland intravenous chemotherapeutic agents known to beassociated with neurotoxicity include methotrexate, cisplatin,cytarabine, and others. However, the contribution of theintrathecal component is unclear. 1Radiological Imaging: No definite CT or MRI findings maybe seen. Imaging thus may be only done to rule out other causesif suspected.Laboratory Tests: Myelin basic protein may be released intothe cerebrospinal fluid. However it is essentially a clinicaldiagnosis.330