Yoram Segev

High b-Value q-Space Analyzed Diffusion-Weighted MRI: Application to Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) which affects nearly one million people worldwide, leading to a progressive decline of motor and sensory functions, and permanent disability. High b‐value diffusion‐weighted MR images (b of up to 14000 s/mm2) were acquired from the brains of controls and MS patients. These diffusion MR images, in which signal decay is not monoexponential, were analyzed using the q‐space approach that emphasizes the diffusion characteristics of the slow‐diffusing component. From this analysis, displacement and probability maps were constructed. The computed q‐space analyzed MR images that were compared with conventional T1, T2 (fluid attenuated inversion recovery (FLAIR)), and diffusion tensor imaging (DTI) images were found to be sensitive to the pathophysiological state of white matter. The indices used to construct this q‐space analyzed MR maps, provided a pronounced differentiation between normal tissue and tissues classified as MS plaques by the FLAIR images. More importantly, a pronounced differentiation was also observed between tissues classified by the FLAIR MR images as normal‐appearing white matter (NAWM) in the MS brains, which are known to be abnormal, and the respective control tissues. The potential diagnostic capacity of high b‐value diffusion q‐space analyzed MR images is discussed, and experimental data that explains the consequences of using the q‐space approach once the short pulse gradient approximation is violated are presented. Magn Reson Med 47:115–126, 2002.

Surgical management of parapharyngeal space tumors: a 10-year review.

OBJECTIVE: The purpose of this article is to describe the diagnostic evaluation and surgical approaches to parapharyngeal space tumors in a tertiary referral center. STUDY DESIGN AND SETTING: The study is a retrospective review of 47 patients diagnosed with tumors of the parapharyngeal space (12 with malignant diseases and 35 with benign lesions) and surgically treated during a 10-year period. The transcervical (40%) and the transcervical-transparotid approaches (46%) were the most commonly performed surgical procedures followed by the orbitozygomatic-middle fossa approach (12%) and the transmandibular approach (2%). RESULTS: The surgical procedures were uneventful and there were no postoperative mortalities. Complications were rare; the most common was transient facial nerve paralysis (5 patients). After an average follow-up of 35 months, only 1 of 35 patients with benign diseases had a recurrence 5 years following transcervical resection of a pleomorphic adenoma. Of 12 patients with malignant tumors, 5 (42%) are alive with no evidence of disease. The sensitivity of preoperative fine needle aspiration biopsy (n = 23 patients) was 87% for detection of malignant disease and specificity was 100%. CONCLUSIONS: Most benign parapharyngeal space tumors can be removed surgically with a low rate of complications and recurrence. Malignant neoplasms, however, carry an ominous prognosis and a low rate of disease-free survival. Fine needle aspiration may be helpful in preoperative diagnostic evaluation of patients with parapharyngeal space tumors.

Antral computerized tomography pre‐operative evaluation: relationship between mucosal thickening and maxillary sinus function

OBJECTIVES to assess the correlation between maxillary sinus inferior mucosal thickening and sinus outflow obstruction. MATERIAL AND METHODS the study included 280 computerized tomography (CT) scans (560 maxillary sinuses). CT aimed to assess sinusitis; trauma to the face and intubated patients were excluded. Mucosal thickening was graded as < 5 mm (1), < 10 mm (2), < 15 mm (3), < 20 mm (4) and > 20 mm (5), and classified by appearance as normal, rounded, circumferential, irregular, or complete. Maxillary sinus outflow was classified as patent or obstructed. RESULTS mucosal thickening was found in 36.1% of the maxillary sinuses, graded as 31.2% (1), 34.2% (2), 12.9% (3), 5.4% (4) and 16.3% (5), and classified as rounded (11.8%), irregular (10.4%), circumferential (8.8%) and complete (5.2%). Sinus outflow was obstructed in 15% of the scans. Mucosal thickening of < 5 mm (11.1%), < 10 mm (36.2%) and > 10 mm (74.3%) was associated with sinus obstruction (P<0.0001). Rounded (6.1%), circumferential (55.2%), irregular (38.8%) and complete (100%) mucosal appearances were associated with sinus obstruction (P<0.001). When statistically combined, a substantial risk for sinus obstruction was observed with irregular mucosal appearance of > 5 mm (56.5% for grade 2 up to 82.6% for grades 3-5) and circumferential appearance (21.4% for grade 1 up to 100% for grades 3-5). A low risk for obstruction was found with the rounded appearance (mean 6.1%). CONCLUSIONS irregular (> 5 mm), circumferential and complete mucosal appearance are associated with an increased risk for sinus outflow obstruction and an ENT consultation is recommended. A rounded mucosal appearance of any grade is associated with a low risk for sinus obstruction. Routine CT scans, including the maxillary sinus ostium, are recommended.

The role of the otorhinolaryngologist in the management of central skull base osteomyelitis.

Background Skull base osteomyelitis (SBO) typically evolves as a complication of external otitis in diabetic patients and involves the temporal bone. Central SBO (CSBO) mainly involves the sphenoid or occipital bones without coexisting external otitis. We characterized a group of patients with CSBO. The endoscopic nasopharyngeal and clival biopsy technique is described. Methods Medical records of patients diagnosed as having SBO were retrospectively analyzed (from 2001 to 2006). Patients’ symptoms and signs, laboratory findings, imaging characteristics, endoscopic clival and periclival histopathology results, treatment, and outcome were retrieved. Results Of 20 patients with SBO, 6 patients without external otitis were studied (age range, 54–76 years; 5 men; mean follow-up, 21 months). All patients suffered from unilateral headache, three of six patients had serous otitis media (SOM), three of six patients had cranial nerve (CN) palsies, and five of six patients had elevated acute-phase reactants. Computed tomography (CT) findings were clival cortical bone erosion and adjacent soft tissue swelling. Magnetic resonance (MR) findings were texture changes and enhancement of the involved bones and soft tissues. Biopsy specimens revealed chronic inflammation. All six patients were treated with antibiotics for 3–6 months. Headache disappeared in five of six patients, SOM resolved in two of three patients, and CN palsies partially recovered in two of three patients. Imaging findings improved in five of six patients. Conclusion CSBO may mimic malignancy and represents a diagnostic challenge. Typical clinical picture and imaging findings together with a positive response to ciprofloxacin may suffice to establish the diagnosis and obviate the need for biopsies. When in doubt, nasopharyngeal and clival biopsies are performed to rule out malignancy.

Systemic corticosteroids for allergic fungal rhinosinusitis and chronic rhinosinusitis with nasal polyposis : A comparative study

Objectives To compare the effect of preoperative high-dose systemic corticosteroids on the radiographic and endoscopic appearance of allergic fungal rhinosinusitis (AFRS) and chronic rhinosinusitis with nasal polyposis (CRSwNP). Study Design and Setting Eight AFRS and 10 CRSwNP patients underwent computed tomographic (CT) scans and then received preoperative 1 mg/kg prednisone for 10 days. CT scans were repeated 1 day before surgery and compared with pretreatment scans (Lund-MacKay radiologic scoring system). The endoscopic appearance was recorded intraoperatively. Results The score dropped from 16 (66.4%) to 4.75 in the AFRS group and from 18.4 (23%) to 14.1 in the CRSwNP group (P = 0.0064). Intraoperatively, most sinus mucosal surfaces appeared normal in the AFRS patients but were markedly edematous in the CRSwNP patients. Conclusion Radiographic response of AFRS to systemic corticosteroids is significantly greater compared with CRSwNP. This finding is supported by endoscopic observation.

Increasing chronic subdural hematoma after endoscopic III ventriculostomy

Abstract Object: Endoscopic III ventriculostomy (ETV) is an effective and a rather safe treatment for noncommunicating hydrocephalus secondary to aqueductal stenosis and other obstructive pathologies. Though not devoid of risk, ETV is increasingly replacing shunt operations, and it prevents related complications, including overdrainage. Methods: We report a rare case of a large chronic subdural hematoma (ChSDH) after ETV in a patient with aqueductal stenosis. Three weeks after he was shunted elsewhere, he presented to us with clinical symptoms of intracranial hypotension and overdrainage. ETV was performed and the shunt removed uneventfully. On routine postoperative MRI a few weeks later, a large ChSDH was noted, the patient being totally asymptomatic. Since the ChSDH grew significantly, causing a mass effect on the follow-up MRI, it was finally drained. Large and increasing ChSDHs have previously been reported secondary to overdrainage after shunt placement, but not after ETV. Conclusions: We conclude that though rare, a ChSDH may evolve even after ETV, if there is a substantial decrease in previously elevated intracranial pressure.

Attachment-oriented endoscopic surgical strategy for sinonasal inverted papilloma

Background It is well documented that inverted papillomas (IP) have a localized attachment site. Still, instead of concentrating on the attachment site, endoscopic surgeons often perform an extended resection similar to the one achieved after external surgery. Objective Our objective was to evaluate an attachment-oriented endoscopic surgical strategy and to determine IP attachment diameter and location. Methods A prospective study was conducted. Thirty-three consecutive patients who underwent endoscopic IP excision (2001-2007) were enrolled. Thirty patients had adequate follow-up. Attachment diameters were measured in 25/33 patients. Surgery included debulking, identifying the precise mucosal attachment site, subperiosteal dissection and excision of the attachment, frozen section control, and resection/drilling of underlying bone. Results The mean measured attachment diameter (n = 25) was 8.4 ± 6 mm (range, 3-23 mm). Attachment locations included maxillary sinus (39%), ethmoid sinus (21%), nasal cavity (21%), frontal sinus (6%), sphenoid sinus (6%), lamina papyracea (3%), and cribriform plate (3%). The mean follow-up (n = 30) was 40 ± 21 months. Three patients had Krouse stage 1, 10 patients had stage 2, and 17 patients had stage 3. Nine patients had undergone previous surgeries. After attachment-oriented endoscopic surgery, three patients had persistent disease. Nasolacrimal duct stenosis was the only complication (n = 1). Conclusion Even advanced IP have small attachments. Their Identification facilitates efficacious resection with minimal morbidity.

Gray–white matter discrimination—a possible marker for brain damage in heat stroke?

INTRODUCTION/OBJECTIVE Heat stroke (HS) is a common medical emergency which carries high morbidity and morality. This study was designed to describe the pattern of central nervous system (CNS) changes as detected by brain CT scan in a case series of six patients suffering from classical and exertional HS. METHODS AND PATIENTS All the patients were admitted in critical condition during the heat wave in the summer of 1999 in Israel. Each was in deep coma with a measured core temperature of over 40 degrees C upon admission to the emergency department. RESULTS Aggressive cooling measures decreased the core temperature to <38 degrees C within 30 min following admission. Two patients (33.3%) died. One of the survivors remained in a vegetative state. Brain CT studies carried out within 4 days of admission in all the patients revealed severe loss of gray-white matter discrimination (GWMD) without signs of acute bleed or significant focal lesion, findings that persisted in repeated brain CTs in one patient who remained in a vegetative state. DISCUSSION AND CONCLUSIONS Loss of GWMD may represent an early and sensitive indication of severe brain damage in patients with severe HS. Further studies in larger groups of patients are warranted in order to determine whether the appearance of GWMD in brain CTs of patients with HS has prognostic value.

Worster-Drought and congenital perisylvian syndromes-a continuum?

A 5-year-old female was evaluated because of severe speech and expressive language delay. On examination, she could hardly speak and communicated through gestures. She manifested severe dysarthria and difficulty in protruding and moving her tongue laterally. She lacked coordination of the swallowing process, with drooling and an increased mental reflex. Her cognitive development was normal, and no associated neurologic dysfunction of the limbs was noted. On follow-up, the child experienced two episodes of seizures at 6 years of age. Magnetic resonance imaging of the brain demonstrated perisylvian and frontal polymicrogyria. Clinical and radiologic findings demonstrated a similarity and continuum between congenital suprabulbar paresis (Worster-Drought syndrome) and perisylvian syndrome.

Evoked potential studies in the antiphospholipid syndrome: differential diagnosis from multiple sclerosis

Background: The CNS manifestations of the antiphospholipid syndrome (APS) can mimic multiple sclerosis both clinically and radiologically. Objective: To compare evoked potential studies in APS patients and patients with multiple sclerosis with similar neurological disability. Methods: 30 APS patients with CNS manifestations and 33 patients with definite multiple sclerosis and similar neurological disability underwent studies of visual evoked potentials (VEP), somatosensory evoked potentials (SSEP) in the upper and lower limbs (UL, LL), and sympathetic skin responses (SSR) in the upper and lower limbs. Results: The neurological manifestations in the APS patients included stroke (n = 17), transient ischaemic attacks (n = 10), and severe headache with multiple white matter lesions on brain MRI (n = 3). Abnormal SSEP (LL), and SSR (UL; LL) were seen in APS patients (37%, 27%, and 30%, respectively) but VEP and UL SSEP were rarely abnormal (10% and 6%, respectively in APS v 58% and 33% in multiple sclerosis; p = 0.0005, p = 0.008). Mean VEP latencies were more prolonged in multiple sclerosis (116 ms v 101 ms, p<0.001). Only one APS patient had abnormal findings in all three evoked potential studies, compared with seven patients in the multiple sclerosis group (p = 0.04) Conclusions: Abnormal VEPs are uncommon in APS in contrast to multiple sclerosis. Coexisting abnormalities in all other evoked potentials were similarly rare in APS. In patients with brain MRI findings compatible either with multiple sclerosis or APS, normal evoked potential tests, and especially a normal VEP, may support the diagnosis of APS.