Carine Delbrouck

Irradiation of cochlear structures during vestibular schwannoma radiosurgery and associated hearing outcome

OBJECT The purpose of this study was to measure the dose of radiation delivered to the cochlea during a Gamma knife surgery (GKS) procedure for treatment of patients with vestibular schwannomas (VSs), and to analyze the relationship between cochlear irradiation and the hearing outcome of these patients. METHODS Eighty-two patients with VSs were treated with GKS using a marginal dose of 12 Gy. No patient had neurofibromatosis Type 2 disease, and all had a Gardner-Robertson hearing class of I to IV before treatment, and a radiological and audiological follow-up of at least 1-year after GKS. The dosimetric data of the volume of the cochlea were retrospectively analyzed and were correlated with the auditory outcome of patients. RESULTS The mean radiation dose delivered to the cochlear volume ranged from 1.30 to 10.00 Gy (median 4.15 Gy). The cochlea received significantly higher radiation doses in patients with worsening of hearing after GKS. A highly significant association between the cochlear and the intracanalicular dose of radiation delivered during GKS was found. CONCLUSIONS During GKS for VSs, relatively high doses of radiation can be delivered to the cochlea. Worsening of hearing after GKS can be the consequence of either radiation injury to the cochlea or the irradiation dose delivered into the auditory canal, or both.

Lobular capillary haemangioma of the nasal cavity during pregnancy

OBJECTIVE We report a pregnant patient with a rapidly growing mass within the nasal cavity, which required pre-operative super-selective embolisation and subsequent removal under general anaesthesia after childbirth. We also discuss the clinical, radiological and histological characteristics of lobular capillary haemangioma, and its treatment. METHOD Case report and literature review. RESULTS Lobular capillary haemangioma is a benign lesion originating in the vascular tissue of skin, mucosa, muscles, glands and bone. These lesions grow rapidly. Nasal localisation is rare. Microtrauma and pregnancy are the most commonly proposed aetiological factors. Reported incidence during pregnancy ranges from less than 2 per cent to approximately 5 per cent. The management of a pregnant woman with such a lesion may be complex, and depends on the severity of symptoms and the status of the pregnancy. Complete surgical excision, with or without pre-operative embolisation, is the treatment of choice. CONCLUSION This uncommon lesion should be considered in any pregnant patient with a mass in the mouth or nasal cavity.

Dosimetric and Clinical Analysis of Spatial Distribution of the Radiation Dose in Gamma Knife Radiosurgery for Vestibular Schwannoma

OBJECTIVES We investigated variations in the distribution of radiation dose inside (dose inhomogeneity) and outside (dose falloff) the target volume during Gamma Knife (GK) irradiation of vestibular schwannoma (VS). We analyzed the relationship between some parameters of dose distribution and the clinical and radiological outcome of patients. METHODS AND MATERIALS Data from dose plans of 203 patients treated for a vestibular schwannoma by GK C using same prescription dose (12 Gy at the 50% isodose) were collected. Four different dosimetric indexes were defined and calculated retrospectively in all plannings on the basis of dose-volume histograms: Paddick conformity index (PI), gradient index (GI), homogeneity index (HI), and unit isocenter (UI). The different measures related to distribution of the radiation dose were compared with hearing and tumor outcome of 203 patients with clinical and radiological follow-up of minimum 2 years. RESULTS Mean, median, SD, and ranges of the four indexes of dose distribution analyzed were calculated; large variations were found between dose plans. We found a high correlation between the target volume and PI, GI, and UI. No significant association was found between the indexes of dose distribution calculated in this study and tumor control, tumor volume shrinkage, hearing worsening, loss of functional hearing, or complete hearing loss at last follow-up. CONCLUSIONS Parameters of distribution of the radiation dose during GK radiosurgery for VS can be highly variable between dose plans. The tumor and hearing outcome of patients treated is not significantly related to these global indexes of dose distribution inside and around target volume. In GK radiosurgery for VS, the outcome seems more to be influenced by local radiation dose delivered to specific structures or volumes than by global dose gradients.

Repeat Gamma Knife surgery for vestibular schwannomas

Background: Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases. Methods: A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases. Results: Mean follow-up duration was 46 months (range 24–110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment. Conclusions: Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment.

Laryngeal aspergillosis in an acquired immunodeficiency syndrome patient

Aspergillosis is a rare infection. It varies considerably in its virulence depending on whether or not the patient affected is immunodepressed. The serious form is characterized by vascular invasion with haematogenic dissemination, tissue infarction and necrosis. The most often affected site is the lung. A laryngeal localization is exceptional and usually results from dissemination from a lower airways portal of entry. Diagnosis is difficult: cultures are only positive in 50 per cent of cases, while in 60 per cent of cases the characteristic histological features reminiscent of sprigs of mistletoe are only found on postmortem examination. In view of the high morbidity and mortality in acquired immunodeficiency syndrome (AIDS) sufferers, this condition must be treated early and aggressively. Treatment is based essentially on amphotericin B and itraconazole.