Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 51, Num. 3, 2003, pp. 425

Neurology India, Vol. 51, No. 3, July, 2003, pp. 425

Focal early onset of delayed radiation encephalopathy with brainstem signs

Varkey BM, Varkey L
Department of Neurology, Indo-American Hospital, Vaikom, Kerala

Correspondence Address:
Department of Neurology, Indo-American Hospital, Vaikom, Kerala

Code Number: ni03144

Sir,
Brain injury following therapeutic radiation encompasses a large spectrum of clinical presentations. A case with a relatively early onset of focal radiation brain injury in a 46-year-old lady is presented. She had left hemifield visual loss and right-sided headache of 2 months duration. Examination showed papilloedema and a left homonymous hemianopia. MRI brain showed a lesion in the right occipito-parietal region with mild contrast enhancement. A right occipital craniotomy and lobectomy was done, which revealed an anaplastic astrocytoma for which she received adjuvant radiotherapy and chemotherapy. A total dose of 60 Gy of radiation was given over 30 fractions in 6 weeks, followed by chemotherapy, 2 courses at 6 weeks interval of Vincristine 2 mg, CCNU 120 mg (on Day 1) and procarbazine 100 mg/day for 5 days (PCV regimen). One week after the second cycle of chemotherapy, she developed an ataxic gait and dysarthria. On examination she was somnolent, had bilateral ptosis, and frozen eyes except for the abduction of the right eye, fixed mid-sized pupils, spastic tongue, dysarthria, brisk jaw jerk, spastic limbs with grade 2-3 power with extensor plantar reflexes. CT brain showed a small periacqueductal hypodensity. MRI brain with contrast showed diffuse confluent hyperintensities on T2 weighted images involving the midbrain, pons and cerebral peduncles. The findings were suggestive of a leukoencephalopathy due to radiation or chemotherapy. With a provisional diagnosis of a focal early delayed radiation encephalopathy, she was put on dexamethasone. Further chemotherapy was abandoned due to her poor functional status. At follow-up after 3 months, she was alert, but still required assistance for her activities of daily living.

Brain injury by therapeutic irradiation is classified according to its time of onset into acute, early delayed (subacute) and late delayed forms.[1],[2] The acute form occurs during the first several days of radiotherapy with headache, nausea, fever, somnolence, and worsening of pre-existing focal symptoms. Early delayed encephalopathy typically occurs at about 2-4 months after radiotherapy, with deterioration in the pre-existing deficits, somnolence and headache.[2] Focal early delayed encephalopathy is seen following high-dose radiotherapy when a portion of the brain, especially the brainstem, is in the treatment portal. MRI shows white matter hyperintensity suggesting demyelination.[2] Spontaneous recovery is seen within two months. Steroids are observed to assist in the recovery.[1],[2] Rarely, a severe form can progress to coma and death. Late radiation injury consists of forms such as focal cerebral necrosis[2] and diffuse cerebral injury[3] which develop around 15-18 months1 after completion of radiotherapy.

The standard chemotherapy regimen does not produce an encephalopathy.[4] Vincristine may produce an axonal sensorimotor peripheral neuropathy. Oral CCNU (lomustine) rarely produces neurotoxicity at conventional doses and procarbazine produces neurotoxicity more commonly when the drug is used intravenously. However, intensive combination chemotherapy with procarbazine, CCNU and vincristine (PCV) may produce an encephalopathy if combined with radiation therapy by sensitizing the white matter to radiation damage.

In our patient the leukoencephalopathic findings on MRI fell within the radiotherapy treatment portal, which along with the chemotherapy regimen may have sensitized her for radiation encephalopathy. The radiation portal inclusion of the brainstem precipitated a focal early delayed type of radiation encephalopathy. A diagnosis of radiation encephalopathy may prompt earlier treatment with dexamethasone or other corticosteroids as some of these complications respond well to steroids.

REFERENCES

1.	New P. Radiation injury to the nervous system. Curr Opin Neurol 2001;14:725-34
2.	Sheline GE. Therapuetic irradiation and brain injury. Int J Radiat Oncol Biol Phys 1980;6:1215-28.
3.	Valk PE, Dillon WP. Radiation injury of the brain. AJNR Am J Neuroradiol 1991;12:45-62.
4.	Postma TJ, van Groeningen CJ, Witjes RJ, Weerts JG, Kralendonk JH, Heimans JJ. Neurotoxicity of combination chemotherapy with procarbazine, CCNU and vincristine (PCV) for recurrent glioma. J Neurooncol 1998;38:69-75.

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