Gamma knife surgery of superficially located meningioma

Abstract

Object. The authors analyzed tumor control rates and complications in patients with superficially located meningiomas after gamma knife surgery (GKS). Methods. Between 1998 and 2003, GKS was performed in 23 patients with 26 lesions in whom follow-up imaging for 1 year or more was available. The male/female ratio was 1:22. The mean age was 59 years. The median tumor volume was 4.7 cm3, and the mean margin dose was 16 Gy at the 50% isodose line. Peritumoral edema was revealed on magnetic resonance (MR) imaging in four patients before GKS. Magnetic resonance imaging and clinical examinations were performed every 6 months after GKS. The mean follow-up duration was 32 months. The tumor shrank in eight cases, was stable in 17, and enlarged in one; thus 25 (95%) of 26 tumors were controlled. A peritumoral high signal on T2-weighted MR images was found in eight lesions and preexisting edema was aggravated in three lesions after GKS. Ten of these 11 patients complained of severe headache, and three patients experienced neurological deficits at the same time after a mean latency of 3 months; however, high signal was not demonstrated on imaging before 6 months on average. Steroid agents, when required, gave relief to all patients. The complication rate was 43% (10 of 23 cases). High signal disappeared in nine patients and decreased in the remaining two. High signal was associated with a high integral dose and a large tumor volume. Tumor shrinkage at the last follow-up examination was more prominent in the patients with symptomatic high signal (p = 0.03). Conclusions. There was a good tumor control rate with a high complication rate. Longer follow up of more patients is needed. Adjusting the dose—volume relationship should be considered to reduce complications.

Stereotactic radiosurgery for benign meningiomas

“…There appears to be an interrelation between tumor size and location, with increasing tumor size correlating to increased complications more often in superficial lesions. Kim et al [61] demonstrated a statistically significant increase in peritumoral edema in SRStreated superficial meningiomas greater than 4.2 cm 3 . In our analysis of the data shown in Table 4, when tumor size is broken down by location as well, only the studies containing tumors in all locations (including superficial tumors) demonstrate a statistical correlation between size and complications.…”

“…They report 5 years PFS of 86% for benign lesions, which is significantly lower than the 95 ± 3.5% 5-year PFS mean for all remaining studies reported in Table 3. Kim et al [61] reported the results of 23 patients with superficial tumors (convexity, parasagittal, tentorial) treated with primary SRS. Despite less than 3 years of mean follow-up, they report 4% tumor progression in the short term with a complication rate of 43%.…”

Development of Dose–Volume Relation Model for Gamma Knife Surgery of Non-Skull Base Intracranial Meningiomas

“…All treatment plans were built with the Leksell Gamma Plan (LGP, Elekta Instruments AB). On average, 9.1 shots (range, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] were used to treat a target lesion. The mean prescription dose of 14.6 Gy (range, [10][11][12][13][14][15][16][17][18][19][20] was given mainly to the 50% isodose surface (range, 45-55%).…”

“…Gamma knife surgery for non-skull base meningiomas resulted in greater complication rates than GKS for skull base meningiomas (1,4,11,15,16). The greater complication rates might correlate with greater rates of high-signal-intensity areas (HSIAs) in T 2 -weighted magnetic resonance imaging (MRI) scans (T 2 WI) acquired after GKS.…”

“…The greater complication rates might correlate with greater rates of high-signal-intensity areas (HSIAs) in T 2 -weighted magnetic resonance imaging (MRI) scans (T 2 WI) acquired after GKS. According to our previous analysis (16), 43% of patients had newly developed or expanded HSIAs on T 2 WI. Although not all of these signal changes (SCs) caused radiation-related symptoms, it seems important to keep the SC rates as low as possible.…”