CYBERKNIFE RADIOSURGERY-TREATMENT OPTION FOR HYPOTHALAMIC HAMARTOMAS (A CASE PRESENTATION)
Dr.Sanjay Chandrasekhar, Dr.S.Balaji Subramanian, Dr.B.Subathira, Ms.S.Mahalakshmi
Department of Radiation Oncology, Apollo Specialty Hospital, Chennai.
Hypothalamic neuronal hamartoma is a rare congenital, non neoplastic heterotopia
variably associated with central precocious puberty and gelastic (laughing) seizures1,2,3,4 They are classified into sessile and pedunculated lesions depending on the width of their attachment to the tuber cinerium and pattern of growth which can be respectively contained inside the hypothalamic parenchyma or mainly expanding toward the ventricular or interpeduncular space4,5,6. Diagnosis is based on the characteristic location,
isointensity to normal brain, lack of contrast enhancement and absence of change in size
and morphology of the mass at follow up. Treatment options include medical management, surgery & radiosurgery.The main limitation of surgery lies in its inability
to completely resect intrahypothalamic lesions without causing neuro metabolic complications.Radiosurgery is an emerging modality to treat hypothalamic hamartomas, providing excellent seizure control7,8,9,10.Cyberknife radiosurgery technique does not require a stereotactic frame which may facilitate its use in children and young adults, offering a noninvasive option of treatment with lower complication rates.
17 year old male patient was evaluated for intractable headache, vomiting &intermittent drop attacks of 2 months duration. Physical examination revealed bilateral papilloedema & diminution of vision in left eye with visual field defect of bitemporal hemianopia.
MR imaging of the brain showed a large suprasellar SOL with mass effect and hydrocephalus. After craniotomy, bilateral VP shunting was done. Biopsy from the vascular tumor showed neuronal cells in nests and loose aggregates separated and admixed with a fibrillary stroma. The cells ranged from normal appearing ganglion cells to more rounded cells with moderate to clear cytoplasm, small clusters of stromal calcification & areas of hemorrhage. IHC was positive for synaptophysin and neurofilament & negative for GFAP. These features were consistent with hypothalamic neuronal hamartoma. Considering the challenging neural and vascular anatomy surrounding the tumor, surgery was deferred in our patient and taken up for Cyberknife radiosurgery. Being the most accurate image guided procedure, providing submillimeter accuracy, Cyberknife allows treatment of the entire lesion as visible on neuroimaging studies including hypothalamic components. A total dose of 27.5Gy was delivered in 5 fractions to the tumor. A dose of 5.5Gy was prescribed to the 80 % isodose line covering 93% of the target volume. The entire treatment was done as outpatient and the patient tolerated the treatment well.
Follow up MRI done at 8 months revealed minimal regression in the size and vascularity of the tumor. Patient had a good clinical response as evidenced by seizure free interval of about 8 months post radiosurgery .There were no neurological complications post-treatment.
Cyberknife radiosurgery is a safe and effective treatment for hypothalamic hamartomas. Radiosurgery provides substantial seizure improvement. Distinct from other surgical treatments, it is non invasive and virtually free of major complications.
PURPOSE OF PRESENTATION:
This case is being presented for its rarity and also to share our experience of treating hypothalamic hamartoma using Cyberknife radiosurgery for the first time in India. In concordance with other reports11,12, Cyberknife Radiosurgery appears to be an effective local treatment option with early clinical outcome and decreased morbidity.
The author(s) declare that they have no competing interests.
The authors would like to place on record the involvement of Dr.B.Chidambaram, Paediatric Neurosurgeon, Childs Trust Hospital, Chennai in the discussions regarding this case and for his academic inputs.