[Pathology of the cerebellopontine angle]. / Pathologie de l'angle pontocérébelleux.

The pathology of the cistern of the cerebellopontine angle is primarily that of the nervous and vascular structures that it contains and of the meninges that line it. Knowledge of its anatomy makes it possible to understand and search for a rare pathology, the hemifacial spasm, due to a conflict between the facial nerve and the vertebral artery and the posterior inferior cerbellerar artery. However, the pathology of the cerebellopontine angle remains especially tumoral. Imaging should not only make the diagnosis but also make an exhaustive, pretherapy, and accurate assessment of the three main tumours found in this area: the vestibular schwannoma, the meningioma, and the epidermoid cyst.

[Von Hippel-Lindau disease: recent advances in genetics and clinical management]. / Maladie de von Hippel-Lindau: progrès génétiques et cliniques récents.

Von Hippel-Lindau (VHL) disease is a hereditary cancer syndrome that predisposes to the development of a panel of highly vascularized tumors including CNS and retinal hemangioblastomas, endolymphatic sac tumors, clear-cell renal cell carcinomas (RCC), pheochromocytomas and pancreatic neuroendocrine tumors. CNS hemangioblastomas and RCC are the two main life-threatening manifestations. The disease is caused by germline mutations in the VHL tumor-suppressor gene that plays a major role in regulating the oxygen-sensing pathway by targeting the hypoxia-inducible factor HIF for degradation in proteasome. Somatic inactivation of the VHL gene occurs also in most sporadic RCC and sporadic CNS hemangioblastomas. The demonstration of the critical role of VHL in angiogenesis is paving the way for the development of new specific drugs that could represent an attractive potential treatment for VHL but also for sporadic RCC and other cancers.

Brain MR diffusion tensor imaging and fibre tracking to differentiate between two diffuse axonal injuries.

We report here two cases of diffuse axonal injury (DAI) studied by MR diffusion tensor imaging (DTI) and fibre tracking (FT) focused on the corpus callosum. In one case, DTI and FT pattern matched the diagnosis of broken white matter tracts. In the other case there was a discrepancy between DTI and FT data that showed unaltered white matter tracts with the presence of intra-cellular oedema. These data suggested that DTI and FT are able to differentiate between traumatic cytotoxic oedema and broken fibres in the case of DAI.

Bilateral dystrophic ossification of the thyroid cartilage appearing as symmetrical laryngeal masses.

Primary cartilaginous lesions of the larynx are relatively uncommon. We present a case of bilaterally pseudocystic lesion of the thyroid cartilage that demonstrated progressive calcification. Pathologic analysis showed features suggesting a dystrophic lesion with no evidence of malignancy. We hypothesize that repetitive microtrauma related to muscular overuse probably led to inflammatory changes at tendinous insertions on the laryngeal cartilage and resulted in dystrophic ossification of the laryngeal cartilage.

Head and neck lesions in the immunocompromised host.

Head and neck lesions are encountered in more than 40-50% in patients with immunosuppression (HIV-infected individuals, diabetes mellitus, transplant recipients, patients treated with immunosuppressive drugs or post-radiotherapy). The organs affected are the salivary glands, the lymph nodes, the sinonasal tract, the orbits, the temporal bones, and the pharyngo-laryngeal mucosa. They are mainly involved by granulation tissue, perivascular and perineural inflammation, and neoplasms. In the pediatric population the temporal bone is the most frequent target organ. The most common clinical manifestation of salivary gland involvement is non-specific bilateral painless enlargement of the parotid gland and xerostomia. Lymphoepithelial cyst, sialosis, and lymphoma may be present. The high rate of salivary gland involvement is probably related to the presence of the human immunodeficiency virus within the saliva. Surgery, sclerotherapy by doxycycline, or low-dose radiotherapy may prevent further growth of tumoral lesions. Sinonasal diseases are the most frequent lesions which manifest in immunosuppressed adult patients (66%). They are associated with a trend of decreased survival rate. Invasive aspergillosis is defined by hyphae in the submucosa, and tumor necrosis without host inflammatory response; it may be lethal in 50-80%, especially when the skull base is involved. Computed tomography shows erosion of bone and extrasinonasal extension. The hypointensity of the lesion on T2-weighted images may suggest the diagnosis. Fungal sinus disease can affect 1-10% of transplant recipients and should be suspected when organ rejection is considered. The temporal bone is the most frequent target organ in the immunosuppressed pediatric population due to Eustachian,tube dysfunction. Otomastoïditis, necrotizing external otitis, and otosyphilis are reported. Prompt treatment may avoid lateral sinus thrombosis. Epithelial neoplasms, lymphomas, and Kaposi's sarcoma may also be considered. Kaposi's sarcoma, the most common neoplasm encountered in patients with AIDS, is an indicator of the progression of human immunodeficiency virus infection to AIDS. The lesions are often multifocal at presentation and may affect the skin, the mucosa, and visceral organs. The pathogenesis is unclear, but cytokines and growth factors may play a role. In conclusion, immunosuppressed patients are likely to develop virulent infection with vascular complications.

Acute epiglottitis: MRI.

We report the MRI findings in an adult with epiglottitis. There was thickening of the epiglottis and left aryepiglottic fold. Management of this life-threatening condition requires imaging only when the diagnosis is uncertain or when an abscess or other complication is suspected.

"Duplicated" or "multiple" cervical internal carotid and vertebral arteries from fenestration, duplication and vasa vasorum to segmental rete.

SUMMARY: The appearance of multiple cervical arteries may be due to a variety of anatomic situations. Arterial fenestrations and duplications have different anatomic origins, with distinct appearances on angiography. They are associated with incomplete segmental development. The vasa vasorum of the internal carotid artery are rarely seen unless enlarged in pathological situations. They represent a peculiar segmental, in-situ, collateral circulation. Retes, on the other hand, correspond to a more complex reconstitution of an early segmental regression. Careful analysis of each of these features is required to choose the best appropriate terminology. The purpose of this paper is to report illustrative cases to enhance the distinctive features of each disposition.

[Anatomic variants of paranasal sinuses]. / Les variantes anatomiques des sinus de la face.

During the last 15 years period, the development of functional endoscopic sinus surgery underlines the needs of a better knowledge of sinonasal anatomy and consequently, of sinonasal anatomic variations. These anatomic variations are widely spread into the population and commonly encountered in daily CT practice. The difference of anatomic landmarks during endoscopic surgery can result in bony transgression and increase the difficulties of the surgery. In fact, functional endoscopic surgery is a blind surgery leading to severe complications with medico-legal impact. Therefore, the anatomic sinonasal variations should be depicted in all sinonasal CT imaging studies irrespective of the indications. Moreover, some anatomical variants may cause certain symptoms.

[Lyrical and musical auditive mental imagery in functional MRI]. / Imagerie magerie mentale auditive lyrique et musicale en IRM fontionnelle d'activation.

PURPOSE: to explore with functional MRI cerebral areas involved in musical and lyrical sounds signal processing with the mental imagery method. MATERIAL: and METHODS: nine volunteers (mean age: 27 years old) underwent functional MRI with BOLD contrast at 1.5 T. Box-car paradigms of partial recollections of musical or lyrical memories tasks were performed. Statistical correlations mappings were calculated and superimposed on previously realigned anatomical reference imaging to observe activated cerebral areas. RESULTS: all except one subjects had activation areas in primary and secondary auditive cortices in the temporal Heschl gyrus and the Planum Temporale, unilaterally (n=2) or bilaterally (n=6) during both mental tasks. Contralateral activation improvement was observed in 4 cases when the lyrical tasks were performed. Temporal and insular regions involved in language processing were observed in eight of nine subjects. CONCLUSION: auditive mental imagery can show in functional MRI cerebral areas involved in auditive functions and some of the areas involved in language processing.

Sinonasal Wegener's granulomatosis: CT characteristics.

Wegener's granulomatosis (WG) is a severe and potentially lethal granulomatosis. Even though no specific radiological criteria exist, CT may suggest the correct diagnosis at an early stage. Recent improvement in the prognosis is related to earlier diagnosis, allowing the initiation of efficient and specific treatment before any severe complications occur. We reviewed a series of WG cases in order to establish the CT diagnostic criteria.

Functional MRI in symptomatic proliferative angiopathies.

Seizures, the main expression of cerebral arteriovenous malformations (AVMs) can be difficult to control medically. We studied fMRI in correlation with clinical findings cerebral activation clusters patterns in relation with singular AVMs (proliferative angiopathy). We carried out blood oxygen-level dependent functional MRI (fMRI) in seven patients with language problems due to capillary ectasia with verbal fluency and repetition language tasks in box-car paradigms. fMRI maps were calculated with cross-correlation coefficients and superimposed on brain anatomy. Five patients had perimalformative and/or contralateral areas of ipsi- and contralateral activation clusters redistribution. One patient who underwent fMRI after a severe focal post-ictal deficit had total hemisphere contralateral activation clusters redistribution.

MR perfusion imaging in a case of cerebral proliferative angiopathy.

Proliferative angiopathy is an uncommon type of cerebral arteriovenous shunt characterized by an extensive capillary network with normal brain intermingled and few clinical symptoms (mostly seizures and headaches). This case report depicts an extensive proliferative angiopathy located in the right hemisphere. Its hemodynamic disturbances were studied with MR perfusion imaging (local or remote areas of increased time to peak, decrease ratio of signal, and relative regional cerebral blood volume values).

Lemierre syndrome: usefulness of CT in detection of extensive occult thrombophlebitis.

We report a case of Lemierre syndrome with extensive suppurative thrombophlebitis involving concomitantly the internal jugular, facial and anterior jugular veins. This case illustrates two unusual clinical and imaging features: the lack of characteristic neck symptoms at admission and a negative initial neck US exam. The value of postcontrast CT of the neck and chest for diagnosis of this potentially life-threatening syndrome is illustrated.

Diffusion-weighted imaging in a case of wernicke encephalopathy.

In a chronic alcoholic patient with progressive confusion, which was consistent with the clinical diagnosis of Wernicke encephalopathy, T2-weighted, FLAIR and diffusion weighted (DWI) MR imaging depicted brain abnormalities located in both medial thalamic nuclei. Apparent Diffusion Coefficient (ADC) measurements in these regions shown unexpected normal values, referring to Wernicke pathological findings and DWI data. DWI may be helpful to diagnose early basal nuclei abnormalities, but may fail to compute ADC values in these locations.

Cochlear implant assessment: imaging issues.

Cochlear implants are electronic auditory prostheses used to rehabilitate deafened persons who have lost their hair cells. They are partly worn externally and partly implanted in the ear. They provide a direct stimulation of the spiral ganglion cells of the cochlear nerve by bypassing the destroyed hair cells. The objectives of this article are to summarise what head and neck surgeons need to know before cochlear implantation and to describe the imaging study protocol used and anomalies to look for. A few explanations are resumed about placement of a brainstem implant.

Merkel cell carcinoma: a rare cause of hypervascular nasal tumor.

Cutaneous neuroendocrine carcinoma, first described in 1972, is an aggressive disease usually occurring in sun-exposed skin. Other sites have been described, however; such tumors occasionally occur within the nasal fossa. A high rate of metastasis (>30%) explains the poor prognosis. Descriptions of the imaging features of these tumors, mainly located in cutaneous region, are rare. We therefore present the imaging features of two cases of Merkel cell carcinoma involving the sinonasal region, suggestive of a hypervascular tumor.

Pulsatile and nonpulsatile tinnitus: a systemic approach.

Tinnitus is an annoying symptom that affects approximately 10% of the population. Unfortunately, in more than 60% of patients, even an extensive workup may not lead to diagnosis, partly because of the diverse causes of the symptom. The imaging protocol study should therefore be adapted to the history of the patient, and each imaging study should underline which etiologies it may exclude. Imaging studies should only be performed after a careful clinical examination and otoscopy. Some characteristic clinical findings are suggestive of such etiologies as pulsed synchronous tinnitus or positional tinnitus, varying with the venous pressure. History of associated neurological deficits, nerve palsies, trauma, ischemic attacks, and visual disturbance (in overweight women) may modify the imaging protocol. Study of the brain and the cervical vessels should always be included to rule out a benign intracranial hypertension. Path and size of the internal carotid artery should be systematically described with regard to the size of the jugular vein and presence of emissary veins. Objective pulsatile tinnitus and tinnitus in children always need a careful imaging study.

Postoperative complications in otospongiosis: usefulness of MR imaging.

BACKGROUND AND PURPOSE: Sensorineural hearing loss (SNHL) is a rare complication of stapes surgery that may arise for many reasons. Usually, the pathogenesis of SNHL can be established by clinical and CT examinations. The purpose of this study was to evaluate the utility of MR imaging when CT findings are normal or not contributive. METHODS: Eleven patients with SNHL (in some instances, associated with vertigo) after stapedectomy, in whom CT showed no well-defined cause, were examined by MR imaging. RESULTS: MR studies established the additional findings of reparative intravestibular granuloma (n = 2), intralabyrinthine hemorrhage (n = 1), and bacterial labyrinthitis (n = 1). In five cases, MR findings were similar to CT findings. In two cases, CT and MR results were normal. Revision surgery was performed in five patients and confirmed the MR findings in each case. CONCLUSION: If CT is not contributive as to the origin of SNHL and vertigo occurring after stapes surgery, then MR imaging may be helpful in these patients.