62. Objective Assessment of Cranial Nerve Neuropathy by Heavy Ions
Azusa Hasegawa, Jun-etsu Mizoe, Hitoshi Miyachi, Shogo Hasegawa, Atsushi Mizota and Hirohiko Tsujii
Keywords: heavy ion therapy, neuropathy, carbon ion radiotherapy
Purpose: In radiation therapy of head and neck cancers, preservation of the Quality Of Life (QOL) is important for patients. Therefore, we evaluated the late effects of carbon ions on the cranial nerve neuropathy as the start for an investigation on safe doses for the cranial nerves. These results are a clinical indicator of the QOL.
Patients and Methods: We selected patients whose trigeminal and/or optic nerves were included in Planning Target Volume (PTV), and we recorded somatosensory evoked potentials before and after carbon ion radiotherapy.
1. Visual Evoked Potential (VEP)
The time-course VEP recording and examination of visual acuity were performed for patients who developed a loss of visual acuity due to tumor invasion. We objectively investigated nerve stimulation using VEP during carbon ion irradiation, and we reconsidered the treatment plan if the nerve pathway is included the in irradiation field.
2. Trigeminal Somatosensory Evoked Potential (TSEP)
TSEP was recorded to examine the clinical availability for patients with/without paresthesia at the time of carbon ion radiotherapy. The stimulating electrodes were composed of a spring clip with upper and lower lips. For patients who were expected to show nerve impairment after irradiation, we recorded the time-course TSEP, and analyzed paresthesia grade.
Results: We are currently still collecting data. This study will be helpful in evaluation of the cranial nerve neuropathy. We present one example case of trigeminal nerve included in PTV. A twenty year-old man was treated using carbon ion radiotherapy. After six months, the early components corresponded with the latency of the normal TSEP (Fig. 27).
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