The eyes speak when the mouth cannot: Using eye movements to interpret omissions in primary progressive aphasia.

Though it may seem simple, object naming is a complex multistage process that can be impaired by lesions at various sites of the language network. Individuals with neurodegenerative disorders of language, known as primary progressive aphasias (PPA), have difficulty with naming objects, and instead frequently say "I don't know" or fail to give a vocal response at all, known as an omission. Whereas other types of naming errors (paraphasias) give clues as to which aspects of the language network have been compromised, the mechanisms underlying omissions remain largely unknown. In this study, we used a novel eye tracking approach to probe the cognitive mechanisms of omissions in the logopenic and semantic variants of PPA (PPA-L and PPA-S). For each participant, we identified pictures of common objects (e.g., animals, tools) that they could name aloud correctly, as well as pictures that elicited an omission. In a separate word-to-picture matching task, those pictures appeared as targets embedded among an array with 15 foils. Participants were given a verbal cue and tasked with pointing to the target, while eye movements were monitored. On trials with correctly-named targets, controls and both PPA groups ceased visual search soon after foveating the target. On omission trials, however, the PPA-S group failed to stop searching, and went on to view many foils "post-target". As further indication of impaired word knowledge, gaze of the PPA-S group was subject to excessive "taxonomic capture", such that they spent less time viewing the target and more time viewing related foils on omission trials. In contrast, viewing behavior of the PPA-L group was similar to controls on both correctly-named and omission trials. These results indicate that the mechanisms of omission in PPA differ by variant. In PPA-S, anterior temporal lobe degeneration causes taxonomic blurring, such that words from the same category can no longer be reliably distinguished. In PPA-L, word knowledge remains relatively intact, and omissions instead appear to be caused by downstream factors (e.g., lexical access, phonological encoding). These findings demonstrate that when words fail, eye movements can be particularly informative.

Extradural balloon obliteration of the empty sella report of three cases (intrasellar balloon obliteration).

Empty sella syndrome is an anatomical and clinical entity composed of intrasellar reposition of the CSF and compression of the pituitary tissue, resulting in a clinical picture of headache, visual field defect, CSF rhinorrhea and some mild endocrinological disturbances. While some cases are primary with no appreciable aetiology, secondary cases are associated with prior operation or radiotherapy of the region. In our series, 3 patients with primary empty sella syndrome were treated by the current approach of extradural filling of the sellar cavity. This technique was first described by Guiot and widely accepted thereafter. We used a detachable silicon balloon filled with HEMA or liquid silicone for obliteration of the sellar cavity and obtained clinically satisfactory results without complications. Visual symptoms regressed and headache disappeared. But at long term follow-up all the balloons were found to be deflated. Despite the facility and efficacy of the technique we do not recommend it in the treatment of the empty sella because the filling of the sella is only transient and relapses may occur.

Traumatic intracranial carotid tree aneurysms.

OBJECTIVE: This study was designed to elucidate the requirements for angiographic evaluation in blunt head injuries, the timing of angiography, and the selection of appropriate therapeutic approaches. METHODS: Twelve cases of traumatic aneurysms (TAs) in the intracranial carotid tree were analyzed in this study. Neurological examination results, computed tomographic scans, pre- and postembolization cerebral angiograms, and follow-up data were included. RESULTS: In 11 of 12 cases, TAs were of cranial base origin; in 1 case, the aneurysm was located in the distal anterior cerebral artery. In seven of the cases with cranial base lesions, aneurysms were located in the intracavernous segment of the internal carotid artery; all of the computed tomographic scans for these cases demonstrated sphenoid sinus wall fractures and hematoma in the sphenoid sinus. In two cases, although the initial angiograms revealed no lesions, a second study performed 2 weeks later demonstrated the presence of aneurysms. Nine of the aneurysms were treated with endovascular techniques, two were managed conservatively, and the remaining one patient died with massive epistaxis while awaiting surgical treatment. No morbidity or additional permanent neurological deficits occurred in the endovascularly treated patient group. CONCLUSION: Patients with head trauma who present with sphenoid sinus fractures and massive epistaxis should be evaluated for the development of TAs as soon as possible. If the patients exhibit fractures without epistaxis, angiography should be deferred for 2 to 3 weeks; if the first angiographic evaluation reveals normal findings, repeated epistaxis should prompt a second angiographic evaluation. Current treatment of TAs involves occlusion of the main artery through the use of endovascular techniques. Cases involving internal carotid artery TAs of cranial base origin and patients who do not tolerate test occlusion require extracranial-to-intracranial bypass surgery.

Meckel-Gruber syndrome.

Meckel-Gruber syndrome is a congenital disorder characterized by occipital encephalocele, polydactyly and polycystic kidneys. This rare syndrome has been reported in the literature as incompatible with life. We present the case of a newborn afflicted with the clinical triad of Meckel-Gruber syndrome. Appropriate treatment instituted in our case led to a good early outcome.

Determination and speciation of mercury in a dental work-place by cold vapour atomic absorption spectrometry and gas-liquid chromatography.

Cold Vapour Atomic Absorption Spectrometry (CVAAS) and Gas-Liquid Chromatography (GLC) have been used for determination and speciation of mercury. Total mercury, methylmercury, ethylmercury and phenylmercury concentrations in urine samples taken from students and staff of a dental work-place were investigated. Air samples were also analyzed. Detection limits, as three times the standard deviation, and in units of ng analyte per ml urine were found to be 1.7, 12, 2.4 and 21 for total mercury, methylmercury chloride, ethylmercury chloride and phenylmercury chloride, respectively.