Postradiation Edema Research Articles

357 Gamma Knife Stereotactic Radiosurgery in the Management of Large Cerebral Arteriovenous Malformations

Abstract Large brain arteriovenous malformations (AVMs) pose management challenge in neurosurgical practice. Management remains conservative unless these AVMs bleed or present with neurological deficits. For patients who require treatment, options are limited with very high treatment-related morbidity. Gamma knife radiosurgery remains an excellent noninvasive option for such AVMs. This is a retrospective study of 74 patients with large AVMs who were treated with gamma knife radiosurgery over 16 years. Sixty-five patients were treated with single-fraction and 9 patients were treated with volume-staged gamma knife radiosurgery. Average follow-up was 4.2 years. In the single-fraction group, 90% patients had SM grade 3 and 4 AVMs while 10% patients had SM grade 5 AVMs. Mean marginal radiation dose was 23.66 Gy. Overall obliteration rate of 66% was observed. Four percent of patients rebled in this group. Postradiation edema was observed in 18% of patient who presented with headache, new-onset seizures, and motor deficits. The symptoms improved with steroid therapy in most patients. Delayed cyst formations were seen in 2 patients. Interestingly, 41% patients showed seizure control after gamma knife radiosurgery. In volume-staging group, 60% patients had SM grade 4 AVMs and 40% patients has SM grade 5 AVMs. All patients were treated in 2 sittings. Average marginal dose used was 23 Gy. These patients showed nearly 80% reduction in the nidus volume at follow-up. No new-onset deficit was observed in this group, and all patients tolerated the treatment very well. Large-volume AVMs can be managed with gamma knife radiosurgery with acceptable risks. Single-fraction gamma knife radiosurgery should be considered for moderate-size AVMs away from critical structures. Large-volume lesions should be treated with volume-staged gamma knife radiosurgery.

Drug-induced sleep endoscopy in adults with sleep-disordered breathing: Technique and the VOTE Classification system

Drug-induced sleep endoscopy (DISE) offers an unique evaluation of the upper airway. After pharmacologic induction of unconscious sedation, it is possible to evaluate endoscopically the structures contributing to upper airway obstruction in sleep disordered breathing. The authors describe DISE techniques and the VOTE classification system for reporting of DISE findings. The VOTE classification focuses on the primary structures that contribute to upper airway obstruction and represents a common language to describe the patterns of obstruction during DISE. The latter can facilitate the scientific evaluation of DISE, including its role in directing treatment.

Unrecognized visual field deficits in children with primary central nervous system brain tumors

Visual field deficits can be a consequence of brain tumor location or treatment. The prevalence of unrecognized visual field deficits in children diagnosed with brain tumors is not known. All children at a single tertiary care pediatric children's hospital diagnosed with a primary brain tumor were tested for visual field deficits by a child neurologist and neuro-ophthalmologist over 16 months. Children with reproducible visual field deficits on two separate occasions were included in the analysis. Patients with optic glioma, craniopharyngioma, or previously known visual field deficits were excluded. Fourteen of 92 (15.2%) children (average 8.9 years, 8 girls) had undiagnosed visual field deficits. Average time between diagnosis of tumor and unrecognized visual field deficit was 3.7 years (range 0-13 years). Unrecognized visual field deficits were not associated with age (P = 0.27) or gender (P = 0.38). Visual field deficits were attributed to direct tumor infiltration (n = 8), postoperative complications (n = 5) and post-radiation edema (n = 1). Deficits included bitemporal hemianopsia (n = 2), homonymous hemianopsia (n = 9), quadrantanopsia (n = 2), and concentric visual field loss (n = 1.) Tumor location included temporal lobe (n = 9), parietal lobe (n = 2), posterior fossa (n = 2), hypothalamic-chiasmatic (n = 2) and multifocal areas (n = 4). Children with temporal lobe tumors were more likely to have unrecognized visual field deficits (P = 0.004). In all 14 patients, visual field deficits were determined by examination only and were not reported by either the patient or caregiver regardless of age. The prevalence of unrecognized visual field deficits in children with brain tumors can be surprisingly high. Serial neuro-ophthalmologic evaluation of children with brain tumors is often required to diagnose a visual field deficit since patient or caregiver reporting may be limited.

Optimal Methods for Staging Rectal Cancer

At present, several modalities exist for the preoperative staging of rectal lesions, including computed tomography (CT), body coil or endorectal coil magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) done by rigid or flexible probes, and positron emission tomography (PET). Staging accuracy for CT ranges from 53% to 94% for T-stage accuracy and from 54% to 70% for N-stage accuracy. Improved CT accuracy is observed at higher disease stages. Body coil MRI has shown T- and N-stage accuracy ranging from 59% to 95% and 39% to 95%, respectively. Endorectal coil MRI has shown improved T- and N-stage accuracy, with rates of 66% to 91% and 72% to 79%, respectively. The development of phased-array MRI, combining high spatial resolution with a larger field of view, offers promise to improve on these rates. EUS, considered the current gold standard, has shown T-stage accuracy ranging from 75% to 95%, with N-stage accuracy ranging from 65% to 80%. Flexible EUS probes have the advantage of being able to access and sample iliac nodes. Recent studies also suggest that three-dimensional EUS may provide greater accuracy than conventional two-dimensional EUS. Limited studies exist on the use of PET in primary tumor staging. PET may upstage disease in 8% to 24% of patients and has also been used in posttreatment restaging and surveillance. Postradiation edema, necrosis, and fibrosis seem to decrease restaging accuracy in all modalities. This article reviews the current literature about the staging accuracy of the various modalities and suggests a staging algorithm for rectal cancer.

Secondary Parkinsonism in Childhood: A Rare Complication After Radiotherapy

Secondary parkinsonism is uncommon in children and exceedingly rare after cranial radiotherapy. This report describes a 14-year-old female who presented with growth retardation as a result of a craniopharyngioma, which was partially resected. A secondary hydrocephalus responded well to shunting. She gradually developed a severe hypokinetic-rigid syndrome 6 months after radiotherapy (54 Gray in 30 daily fractions of 1.8 Gray). In addition, her vigilance decreased. Magnetic resonance imaging revealed increased signal intensity on T2-weighted images in the globus pallidus bilaterally. Nuclear scans indicated only a marginal striatal dopaminergic deficit and revealed decreased metabolism in the thalamus bilaterally. Treatment with dopamine agonists resulted in minor improvement in motor function. Magnetic resonance imaging investigations 3 months later disclosed a decrease of signal intensity changes of the globus pallidus. Gradually, bradykinesia diminished slightly and vigilance increased little. In conclusion, secondary and partially reversible parkinsonism can occur in children after radiotherapy. We suggest that focal encephalopathy resulting from postradiation edema secondary to microangiopathy led to dysfunction of the globus pallidus and thalamus.

Radiation-Induced Edema after Gamma Knife Treatment for Meningiomas

A retrospective study was performed to analyze some parameters in a consecutive series of 35 Gamma Knife treatments in 34 patients with benign meningiomas. The minimum dose to the tumors was never less than 12 Gy. The follow-up period was from 1 to 3 years. A semiquantitative method of tumor volume assessment was used to measure the tumor response to treatment. The presence and clinical significance of postradiation edema were noted. Even in this short follow-up period, 11 of the 35 tumors were reduced in volume. No tumors increased in size. Edema developed preferentially in nonbasal tumors, especially those around the midline and sagittal sinus. In all but one case where radiation-induced edema was observed was the margin tumor dose 18 Gy or more. It is suggested that doses of 18 Gy or more should probably be avoided in the Gamma Knife treatment of meningiomas and that the greatest care should be taken in selecting non-skull base tumors for this form of treatment.

Distinguishing tumor recurrence from irradiation sequelae with positron emission tomography in patients treated for larynx cancer

Purpose : Distinguishing persistent or recurrent tumor from postradiation edema, or soft tissue/cartilage necrosis in patients treated for carcinoma of the larynx can be difficult. Because recurrent tumor is often submucosal, multiple deep biopsies may be necessary before a diagnosis can be established. Positron emission tomography with 18F-2fluoro-2deoxyglucose (FDG) was studied for its ability to aid in this problem. Methods and Materials : Positron emission tomography (18FDG) scans were performed on 11 patients who were suspected of having persistent or recurrent tumor after radiation treatment for carcinoma of the larynx. Patients underwent thorough history and physical examinations, scans with computerized tomography, and pathologic evaluation when indicated. Standard uptake values were used to quantitate the FDG uptake in the larynx. Results : The time between completion of radiation treatment and positron emission tomography examination ranged from 2 to 26 months with a median of 6 months. Ten patients underwent computed tomography (CT) of the larynx, which revealed edema of the larynx (six patients), glottic mass (four patients), and cervical nodes (one patient). Positron emission tomography scans revealed increased FDG uptake in the larynx in five patients and laryngectomy confirmed the presence of carcinoma in these patients. Five patients had positron emission tomography results consistent with normal tissue changes in the larynx, and one patient had increased FDG uptake in neck nodes. This patient underwent laryngectomy, and no cancer was found in the primary site, but nodes were pathologically positive. One patient had slightly elevated FDG uptake and negative biopsy results. The remaining patients have been followed for 11 to 14 months since their positron emission studies and their examinations have remained stable. In patients without tumor, average standard uptake values of the larynx ranged from 2.4 to 4.7, and in patients with tumor, the range was 4.9 to 10.7. Conclusion : Positron emission tomography with labeled FDG appears to be useful in distinguishing benign from malignant changes in the larynx after radiation treatment. This noninvasive technique may be preferable to biopsy, which could traumatize radiation-damaged tissues and precipitate necrosis.

MRI differentiation of recurrent nasopharyngeal carcinoma from postradiation fibrosis

A prospective study was performed to determine the usefulness of magnetic imaging (MRI) in differentiating local recurrence versus post-irradiation fibrosis in 72 patients after radiotherapy of nasopharyngeal carcinoma (NPC). All patients had a soft-tissue mass in the nasopharynx demonstrated by computed tomography. A total of 29 patients had tumor recurrence; 40 patients had only radiation fibrosis; 1 patient had postradiation edema and 2 patients had inflammatory changes. Based on the differences in signal intensity on T2-weighted Images, MRI may be promising as a noninvasive method for differentlating radiation fibrosis from local recurrent NPC. However, the signal intensity pattern of the tumor is not specific and may be seen in radiation edema and infection.

Laser Epiglottectomy: Endoscopic Technique and Indications

At the American Laryngological Association annual meeting, Steven Zeitels, MD, C. W. Vaughn, MD, and G. T. Simpson, MD, of Boston University, reported their experience in managing various supraglottic pathologies in 49 patients by laser epiglottectomy. Utilizing general endotracheal anesthesia, the majority of patients (23) were treated for supraglottic airway obstruction caused by benign or malignant tumors, inflammatory processes, and postradiation edema. Other indications for laser epiglottectomy included diagnosis and staging of supraglottic carcinoma (18 patients), debulking advanced tumors (14 patients), and treatment of localized carcinomas and improvement of glottic visualization due to epiglottic obstruction following trauma or radiation (four patients). This unique series is enhanced by the investigators' concise elaboration of the actual surgical technique. Such a report provides useful information to both the novice and experienced laryngeal surgeon. The lack of significant postoperative problems with alimentation, airway, or voice, attest to the skill of these investigators and the

Neck neoplasms: MR imaging. Part II. Posttreatment evaluation.

Thirty-three patients who had undergone prior surgery and/or radiation therapy for malignant neoplasms of the neck were studied with magnetic resonance (MR) imaging. Twenty-seven of these patients were also evaluated with computed tomography (CT). Ten patients were healthy posttreatment volunteers, and 23 had documented tumor recurrence. MR images better demonstrated normal muscular landmarks, especially in patients with obliterated fat planes. Areas of posttreatment fibrosis or scarring were low in signal intensity with all MR pulse sequences. However, in three patients, high signal intensity from postradiation edema of the supraglottic area mimicked neoplasm. In patients with recurrent tumor, MR imaging was superior to CT in defining the relationship of tumor and muscle and in demonstrating vascular anatomy when no intravenous contrast material was given during the CT examination. In two patients tumor and fibrosis were separated on MR images because of signal intensity differences. CT scans, however, showed adjacent bone and cartilage anatomy better. Our data indicate that an MR examination may be helpful in patients in whom CT is indeterminate either because of anatomical distortion or suboptimal demonstration of vascular anatomy.