伽玛刀治疗听神经瘤疗效观察

目的探讨伽玛刀治疗听神经瘤的疗效。方法应用玛西普伽玛刀治疗听神经瘤152例,其中84例获得完整随访资料,随访时间为12～89个月。结果肿瘤体积缩小57例（67．9％）、不变23例（27．3％）、增大4例。听力保留率为70．6％（36／51）,出现患侧面神经一过性受损4例（5．3％）,出现三叉神经功能受损症状3例（2例为一过性,1例经治疗后缓解）。结论伽玛刀治疗听神经瘤有较高的肿瘤生长控制率,对相关颅神经损伤小,并发症少,是一种安全有效的治疗方法。     

Post-surgical vestibular schwannoma remnant tumors: What to do?

BackgroundVestibular schwannomas (VS) are benign tumors of the vestibular nerve's myelin sheath. The current trend in VS surgery is to preserve at the facial function, even if it means leaving a small vestibular schwannoma tumor remnant (VSTR) after the surgery. There is no defined therapeutic management VSTR. The aim of this study was to assess the evolution of the VSTR to define the best therapeutic management and identify predictive factors of VSTR progression.MethodsAmong the 256 patients treated surgically for VS in the Department of Neurosurgery at Angers University Hospital, 33 patients with a post-surgical VSTR were included in this retrospective study. For all surgical patients, the data collected were age at diagnosis, the Koos classification, the surgical access, the existence of a type 2 neurofibromatosis (NF2), the TR location and size on control MRI-scans. Patients had a bi-annual follow-up with clinical status and VSTR size assessment with MRI-scan. Survival analyzes were performed to determine the time and rate of VSTR progression, and identify factors of progression.ResultsThe mean follow-up of the population was 51 months. All VS remnant progression occurred between 38 and 58 months after surgery. In non-NF2 patients with first follow-up MRI-scan three months after surgery, 43% presented a spontaneous regression, 50% a stability and 7% a progression of the VSTR. In the same population with the 1-year MR-scan after surgery as baseline, 25% presented a spontaneous regression, 62.5% a stability and 12.5% a VSTR progression. These data are consistent with the data reported in the literature. The post-operative facial function impairment and an initial remnant ≥ 1.5 cm³ were found to be significant risk factors of VS remnant progression in non-NF2 population in univariate analysis (P = 0.048 and 0.031) but not in multivariate analysis.ConclusionIn our experience, the best therapeutic management of the post-surgical VSTP in non-NF2 patients with no risk factor of progression is a simple clinical radiological follow-up otherwise complementary radiosurgery should be considered.     

Significant disparity in base and sugar damage in DNA resulting from neutron and electron irradiation

In this study, a comparison of the effects of neutron and electron irradiation of aqueous DNA solutions was investigated to characterize potential neutron signatures in DNA damage induction. Ionizing radiation generates numerous lesions in DNA, including base and sugar lesions, lesions involving base–sugar combinations (e.g. 8,5′-cyclopurine-2′-deoxynucleosides) and DNA–protein cross-links, as well as single- and double-strand breaks and clustered damage. The characteristics of damage depend on the linear energy transfer (LET) of the incident radiation. Here we investigated DNA damage using aqueous DNA solutions in 10 mmol/l phosphate buffer from 0–80 Gy by low-LET electrons (10 Gy/min) and the specific high-LET (∼0.16 Gy/h) neutrons formed by spontaneous ²⁵²Cf decay fissions. 8-hydroxy-2′-deoxyguanosine (8-OH-dG), (5′R)-8,5′-cyclo-2′-deoxyadenosine (R-cdA) and (5′S)-8,5′-cyclo-2′-deoxyadenosine (S-cdA) were quantified using liquid chromatography–isotope-dilution tandem mass spectrometry to demonstrate a linear dose dependence for induction of 8-OH-dG by both types of radiation, although neutron irradiation was ∼50% less effective at a given dose compared with electron irradiation. Electron irradiation resulted in an exponential increase in S-cdA and R-cdA with dose, whereas neutron irradiation induced substantially less damage and the amount of damage increased only gradually with dose. Addition of 30 mmol/l 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), a free radical scavenger, to the DNA solution before irradiation reduced lesion induction to background levels for both types of radiation. These results provide insight into the mechanisms of DNA damage by high-LET ²⁵²Cf decay neutrons and low-LET electrons, leading to enhanced understanding of the potential biological effects of these types of irradiation.     

Gamma knife radiosurgery cured hydrocephalus in non-hemorrhagic brain stem arteriovenous malformation

A 13-year-old boy, with a history of intermittent headache and transient diplopia, was found to have non-hemorrhagic cerebral arteriovenous malformation in the midbrain tegmental region associated with hydrocephalus. Gamma knife radiosurgery was performed at 16 Gy with 75% marginal dose. Posttreatment course was uneventful. Follow-up MR imaging at one year after the treatment revealed complete disappearance of the abnormal vascular flow voids. The size of each ventricle at the treatment and at one year after treatment were as follows; 60.2 cc and 20.9 cc in the lateral ventricles, 3.7 cc and 2.7 cc in the third ventricle. The hydrocephalus might be caused by obstructive mechanism but mostly by high venous pressure due to the shunt blood flow. The goal of treatment for hydrocephalus should be nidus obstruction and normalizing the vascular flow.     

三叉神经痛伽玛刀治疗前MRI扫描序列研究

目的探讨伽玛刀治疗三叉神经痛MRI定位的最佳扫描序列。方法选择2004年7月-2006年3月行伽玛刀手术的原发性三叉神经痛患者60例,随机分为3组,每组各20例。伽玛刀术前上头架定位,然后对3组分别采用快速自旋回波序列（Turbo Spin Echo,TSE）、增强三维小角度激发快速梯度回波序列（enhanced three-dimensiunal fast low angle shot,enhanced3D-FLASH）、三维结构干涉稳态序列（three-dimensional constructive interferencein steady state,3D-CISS）进行扫描,观察三叉神经及周围血管的显示情况。结果①TSE扫描20例三叉神经,14例显示优,血管显示一般。②增强3D-FLASH扫描三叉神经,18例显示优,2例显示良,周围血管显示优。③3D-CISS扫描三叉神经,20例均显示优,周围血管显示良。结论 3D-CISS和增强3D-FLASH序列的融合影像能够清晰地显示三叉神经根及周围血管,有利于伽玛刀的精确定位,具有较高的临床应用价值,可以作为伽玛刀治疗原发性三叉神经痛的常规定位方法。