Indian Journal of Neurosurgery Vol. 1 ■ Issue 1 ■ January-March 2012 78 Access this article online Quick Response Code: Website: www.ijns.in DOI: 10.4103/2277-9167.94377 CASE REPORT 78.9 mSv (63.6 mSv external and 16.3 mSv internal) (1 mSv = 1 mGy). On examination, patient was found to have left sided sensorineural hearing loss. Rest of the central nervous system examination was within normal limits. No neurocutaneous markers were noted. Pure tone audiometry (PTA) revealed a 30 decibel sesorineural hearing loss in left ear. Magnetic resonance imaging (MRI) of brain revealed a left sided cerebello-pontine angle tumor originating from the left internal acoustic meatus, isointense on T1W and hyperintense on T2W images with homogenous post-contrast enhancement. The tumor was 1.6 × 1.4 cm in size [Figure 1]. The patient subsequently underwent radiosurgery (Gamma- knife) and is presently on follow up. Address for correspondence: Dr. Deepak Agrawal, Department of Neurosurgery and Gamma-knife, All India Institute of Medical Sciences, New Delhi - 110 029, India. E-mail: drdeepak@gmail.com INTrODuCTION There are various case reports and short series regarding radiation-induced CNS tumors following high dose therapeutic radiotherapy. [1-9] Most of these tumors are gliomas, sarcomas, meningiomas, [2,3,5,8,10] and acoustic neuromas are comparatively very rare. [1,4,6,7] On the other hand, exposure to chronic low dose ionizing radiation which occurs as an occupational hazard of working in a controlled radiation environment has never been shown to be linked to carcinogenesis. CASe rePOrT A fifty-year-old male patient, an atomic energy scientist by occupation, working at the Regional Atomic Reactor Centre in India, presented in 2008 to our Gamma Knife department with a history of left sided hearing loss for one year. Patient also had tinnitus for the same duration. No features of raised intracranial pressure were present. Patient was exposed to ionizing radiation during his stint at the Atomic Energy Reactor from 1982 to 1992 and his total cumulative radiation exposure was ABSTRACT Although exposure to high dose ionizing radiaton (following therapeutc radiotherapy) has been incriminated in the pathogenesis of many brain tumors, exposure to chronic low dose ionizing radiaton has not yet been shown to be associated with tumorigenesis. The authors report a case of a 50-year-old atomic reactor scientst who received a cumulatve dose of 78.9 mSv over a 10-year period and was detected to have an acoustc neuroma another 15 years later. Although there is no proof that exposure to ionizing radiaton was the cause for the development of the acoustc neuroma, this case highlights the need for extended follow-up periods following exposure to low dose ionizing radiaton. Key words: Acoustc neuroma, ionizing radiaton, oncogenesis, occupatonal hazard Low dose ionizing radiation induced acoustic neuroma: A putative link? Sachin A. Borkar, Deepak Agrawal Department of Neurosurgery and Gamma-knife, All India Institute of Medical Sciences, New Delhi, India Figure 1: Contrast-enhanced magnetc resonance imaging (MRI) of brain showing homogenously enhancing left cerebello-pontine angle tumor originatng from lef internal acoustc meatus suggestve of acoustc neuroma This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.