hemangioblastomas are benign , highly vascular tumors most frequently arising in the cerebellum , brainstem , or upper cervical cord . the remaining are seen in association with von hippel - lindau ( vhl ) disease , an inherited autosomal dominant disorder arising from mutation in the vhl tumor suppressor gene . although , traditionally , surgical resection has been considered the treatment of choice for hemangioblastomas , all may not be amenable to complete surgical resection in view of site , vascularity , and number . furthermore , there is a significant risk of complications following surgery . as the natural history involves recurrence and onset of new lesions , surgery may be less suitable in some patients . recently , stereotactic radiosurgery ( srs ) has become an attractive alternative to surgery with encouraging results . we wish to report a series of 10 cases of hemangioblastomas treated by radiosurgery at our center over a 14-year period . this retrospective study was conducted on all patients of hemangioblastoma who underwent srs at our institute over the period of 14 years ( 19982011 ) . medical records and radiological studies of all the patients srs was performed with model b leksell gamma knife ( elekta , inc . ) . the procedure began with the application of a leksell stereotactic frame with the patient under local scalp anesthesia . following this , all patients underwent high - resolution magnetic resonance imaging ( mri ) , which was exported to a computer workstation via the hospital ethernet for dose planning . in all patients , the target volume was defined as the enhancing tumor volume . the mean volume of tumors was 1.635 cm ( range from 1.8 mm to 7.6 cm ) . the prescription isodose ( 50% isodose ) ranged from 14 gy to 25 gy with a median of 25 gy . srs was performed with model b leksell gamma knife ( elekta , inc . ) . the procedure began with the application of a leksell stereotactic frame with the patient under local scalp anesthesia . following this , all patients underwent high - resolution magnetic resonance imaging ( mri ) , which was exported to a computer workstation via the hospital ethernet for dose planning . in all patients , the target volume was defined as the enhancing tumor volume . the mean volume of tumors was 1.635 cm ( range from 1.8 mm to 7.6 cm ) . the prescription isodose ( 50% isodose ) ranged from 14 gy to 25 gy with a median of 25 gy . over the study period , 10 patients of hemangioblastoma ( with a total of 27 lesions ) underwent srs at our institute . the mean age of the patients was 32.9 years , ranging from 20 to 44 years . seven patients were males , and three were females . out of the 10 patients , eight patients had vhl disease ( 80% ) while two patients had sporadic hemangioblastomas . of the eight patients with vhl disease , five had multiple intracranial lesions , and other three had single intracranial lesions [ table 1 ] . one of these patients ( patient number 5 ) was referred to us from a peripheral center when the surgery had to be aborted because the patient developed bradycardia intraoperatively . of the three patients who underwent primary radiosurgery , two had multiple lesions , and the third opted for radiosurgery . two patients had undergone ventriculoperitoneal ( vp ) shunt for raised intracranial pressure prior to radiosurgery ( patient number 7 and 9 ) . clinically , most of the patients presented with cerebellar symptoms ( five ) , followed by headache ( three ) , myelopathy ( two ) , and multiple cranial nerve involvement ( one ) [ table 1 ] . in this study , of a total of 27 lesions , 25 were intracranial , and two were located in the spinal cord . as our center lacks the facility of cyber - knife , the spinal lesions could not be managed by radiosurgery ( patient number 3 and 4 ) and , therefore , underwent surgery . our patient number 7 had six intracranial lesions including one lesion at the obex [ table 1 ] . this lesion at the obex was not treated by gamma knife to prevent damage to the brainstem . six patients remained recurrence - free for a mean period of 48 months ( range 19108 months ) . two ( patient number 6 and 10 ) of these demonstrated radiological decrease in tumor volume [ figure 1 ] . in patient number 5 , the lesion disappeared completely over 4 years following gamma knife and had not recurred over the 9 years of follow - up . however , he developed a new lesion at the craniovertebral junction , which required surgery . another patient ( patient number 1 ) showed radiological evidence of decrease in mural nodule , but the cyst volume had increased . he was kept under close follow - up and was asymptomatic at the last follow - up at 40 months [ figure 2 ] . axial gadolinium - enhanced magnetic resonance images of patient number 10 showing mural nodule with a small cyst ( a ) . 1 year after radiosurgery , there was a significant decrease in the size of the mural nodule ( b ) axial gadolinium - enhanced magnetic resonance images of patient number 1 showing mural nodule with a small cyst ( a ) . 1 year after radiosurgery , there was a decrease in the size of the mural nodule with increase in the cyst size ( b ) causing significant compression on the fourth ventricle two patients ( patient number 2 and 3 ) who had large cystic lesions responsible for the cerebellar symptoms persisted to be symptomatic even after radiosurgery . hemangioblastomas are highly vascular , well - circumscribed , benign tumors of the central nervous system . they comprise only about 12.5% of all cranial tumors and 712% of posterior fossa tumors . they are composed of stromal cells , abundant capillaries , pericytes , and mast cells and categorized as who grade i tumors of uncertain origin . type 1 , accounting for 5% of posterior fossa hemangioblastomas , is a simple cyst without a macroscopic nodule . type 2 is a cyst with a mural nodule and accounts for 60% of posterior fossa hemangioblastomas . type 3 is solid tumors without a cystic component ( 26% ) , and type 4 is solid tumors with small internal cysts ( 9% ) . the higher proportion may be explained due to multicentricity of lesions in this group of patients and , therefore , a higher likelihood of them undergoing radiosurgery . the presenting features depend on the location of the lesion and may be headache , cerebellar signs , and nystagmus . symptoms are usually slowly progressive giving time to the treating physician to individualize the treatment modality . surgical resection has traditionally been considered the treatment of choice for hemangioblastomas . classically , hemangioblastomas have a small , well - delineated , vascular mural nodule making them susceptible to radiosurgery . radiosurgery is a noninvasive , day care procedure where multiple lesions may be treated in the same sitting with satisfactory tumor control . moss et al . reported actuarial control rates of 84% and 81% at 3 and 5 years , respectively , in 64 lesions with at least 2 years of follow - up . in their review of 67 cases , matsunaga et al . described a tumor control rate of 83.6% over a mean period of 63 months . however , as srs treats only the solid component of the tumor , it may not be a good treatment option in a patient with mass effect secondary to a cystic component . moreover , studies have demonstrated that radiation can at least transiently induce increases in vascular permeability , leading to peritumoral edema , and cyst formation . in their study of 11 hemangioblastomas , niemel et al . reported that surgical evacuation of the cyst was done after radiosurgery in three of five cystic hemangioblastomas . reported five lesions undergoing increase in cyst volume after radiosurgery with one necessitating surgery to resect the cystic mass . suggested that although srs was good for hyper vascular tumors , it was not effective for cystic tumors . of their 13 patients undergoing srs , two developed cyst expansion requiring surgery . a more recent study by moss et al . reported six such lesions treated with surgical drainage and resection <3 months after srs because of symptomatic cyst growth . they hypothesize cessation of fluid collection occurring nearly 1 year after srs . in our series , two patients ( patient number 2 and 3 ) who had type 2 hemangioblastomas with large cystic lesions responsible for the cerebellar symptoms persisted to be symptomatic even after radiosurgery . these patients underwent surgery at 5 months and 10 months , respectively . in retrospect , the authors feel that cyst aspiration followed by srs might have been better treatment options for these two patients . the authors feel that type 3 , 4 , and selective cases of type 2 hemangioblastomas are better candidates for srs . in general , srs serves as a new modality for treatment in unresectable lesions , multiple tumors , recurrent cases , and in cases with subtotal resection . advise srs in cases of unresectable tumors with mass effect ( may be preceded by stereotactic cyst aspiration ) and after incomplete resection in resectable tumors . according to them , for asymptomatic lesions in vhl , srs is indicated if the size is more than 5 mm , and the lesion shows a cystic component or radiological progression . in their study , tago et al . kano et al . reported a better prognosis in cases with solid tumor , tumor volume < 3.2 ml , and marginal dose > 15 gy . in our series , the higher marginal dose ( median of 25 gy ) might explain why in three of our cases , there was a reduction in the size of the mural nodule , and none of other lesions showed an increase in the nodule 's size . the authors believe that gamma knife should be considered the first - line of management for lesions <3 cm in maximum diameter without significant mass effect . the absence of growth seen at follow - up may simply be a period of quiescence . therefore , it may be difficult to comment with conviction whether the local tumor control rate in an absence of decrease in size can actually be attributed to srs . yamamoto et al . argued that the absence of growth would not mean treatment unless significant growth was seen in tumor before radiosurgery . hence , long - term follow - up is required before any survival benefit may be attributed to srs . kano et al . reported new lesions outside the irradiated area in 10 of their 32 patients . in our study , one patient ( patient number 5 ) developed a new lesion at the cranio - vertebral junction , which was outside the irradiated area [ table 1 ] . at our institute , follow - up mri is done 6 months after radiosurgery and then yearly for the first 5 years . in our study , page et al . reported symptomatic radiation necrosis requiring vp shunt and corticosteroid therapy in one of their patients . it may be a significant problem in cases with multiple lesions with overlapping radiation fields . moss et al . reported 11 tumors in their series with radiation necrosis . in our series , radiosurgery was deferred for a lesion at the obex in one of the patients ( patient number 7 ) to avoid radiation toxicity to brainstem [ table 1 ] . another patient ( patient number 6 ) showed asymptomatic radiation necrosis [ table 1 ] . srs appears to be a suitable modality of treatment for hemangioblastomas in certain conditions , especially unresectable , recurrent , multiple , and subtotally resected tumors . however , cases with a cystic component might show an increase in the size of the cyst and , therefore , need to be monitored closely .
background : although gamma knife has been advocated for hemangioblastomas , it is not used widely by neurosurgeons.objective:we review our experience over 14 years in an attempt to define the role of stereotactic radiosurgery ( srs ) in the management of hemangioblastomas.patients and methods : a retrospective study was conducted on all patients of hemangioblastoma who underwent srs at our institute over a period of 14 years ( 19982011 ) . 
 gamma knife plans , clinical history , and radiology were reviewed for all patients.results:a total of 2767 patients underwent gamma knife during the study period . 
 of these , 10 ( 0.36% ) patients were treated for 24 hemangioblastomas . 
 eight patients ( 80% ) had von hippel - lindau disease while two had sporadic hemangioblastomas . the median peripheral dose ( 50% isodose ) delivered to the tumors was 29.9 gy . clinical and radiological follow - up data were available for eight patients . 
 of these , two were re - operated for persisting cerebellar symptoms . 
 the remaining six patients were recurrence - free at a mean follow - up of 48 months ( range 19108 months ) . 
 one patient had an increase in cyst volume along with a decrease in the size of the mural nodule.conclusions:srs should be the first option for asymptomatic hemangioblastomas . despite the obvious advantages , gamma knife is not widely used as an option for hemangioblastomas .