1/7. Temporary and permanent signs of interhemispheric disconnection after traumatic brain injury.The corpus callosum is frequently damaged by closed head traumas, and the resulting deficits of interhemispheric communication may vary according to the specific position of the lesion within the corpus callosum. This paper describes a single case who suffered a severe traumatic brain injury resulting in a lesion of the posterior body of the corpus callosum. Among the classical symptoms of interhemispheric disconnection, left hand anomia, left upper limb ideomotor dyspraxia, left visual field dyslexia and dysnomia, and left ear suppression in a dichotic listening task were observed shortly after the injury but recovered completely or almost completely with the passage of time. The only symptom of interhemispheric disconnection which was found to persist more than 4 years after the injury was an abnormal prolongation of the crossed-uncrossed difference in a simple visuomotor reaction time task. This prolongation was comparable with that observed in subjects with complete callosal lesions or agenesis. The results suggest that the posterior body of the corpus callosum may be an obligatory interhemispheric communication channel for mediating fast visuo-motor responses. The transient nature of other symptoms of interhemispheric disconnection suggests a relatively wide dispersion of fibers with different functions through the callosal body, such that parts of them can survive a restricted lesion and allow functional recovery of hemispheric interactions. An assessment of the evolution in time of symptoms of interhemispheric disconnection following restricted callosal lesions may reveal fine and coarse features of the anatomo-functional topography of the corpus callosum.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
2/7. hearing loss in amphetamine users.Sensory perceptions are modified by amphetamines. Prolonged and heavy use can lead to neuronal damage, neurotransmitter depletion and receptor supersensitivity. Sensorineural deafness had been reported in chronic users of volatile inhalants, alcohol and heroin. There are no reports of hearing problems with amphetamines. hearing loss was identified in seven amphetamine-dependent inpatients in the detox unit at Al Amal Hospital, Jeddah. Subjects were men aged 18 and over who met DSM IV criteria for substance dependence. The hearing loss was suspected on clinical grounds during the admission interview, and was quite noticeable. Both ears were similarly affected. The symptom mostly appeared three to eight hours after ingestion of the tablets, and did not develop every time the drug was used. Hearing was apparently recovered in every case within four to ten days of cessation of amphetamine use. During the hearing loss, sounds were perceived as less loud and less sharp compared to normal. These cases suggest that chronic amphetamine use may result in reversible hearing loss. The various mechanisms by which this might occur are discussed. The author concludes that these observations should be replicated with a large group of subjects and recommends further investigations to elucidate the nature and site of the damage.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
3/7. wolfram syndrome.The wolfram syndrome is a rare dysmorphogenetic disease of autosomic recessive hereditary nature. The pathogenesis of the disease is still not well known. It is characterised by the presence of diabetes insipidus, diabetes mellitus, optic atrophy and deafness. Other anomalies, such as renal outflow tracts and multiple neurological disorders may develop later. In our case report the diabetes mellitus appeared at the age of 4; the hearing loss and renal disturbances at the age of 11; the optic atrophy at the age of 16. No signs of ataxia, diabetes insipidus and neurologic anomalies were found. The diagnosis of wolfram syndrome is not always easy in the first stages of the disease. The suspect may come from the presence of a juvenile diabetes mellitus asssociated with optic atrophy. For the diagnosis a valid clue can be given from the results of some clinical tests such as the positivity of the visual evoked potentials and the retinogram reliefs and the exclusion of the autoimmune origin of the diabetes mellitus. Other signs such as the progressive sensorineural hearing loss, the presence of nystagmus and of urodynamic disturbances and renal complications makes the diagnosis of this syndrome easier.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
4/7. The facio-audio-symphalangism syndrome in a four generation family with a nonsense mutation in the NOG-gene.We report a four generation family with features of the facio-audio-symphalangism syndrome. This condition is characterized by proximal symphalangism, conductive hearing loss due to stapes fixation and a distinctive facies. A novel nonsense mutation in the NOG gene on chromosome 17q22 was identified in the patients. The variable expression and progressive nature of the syndrome is well illustrated by this family. The role of Noggin as the causative factor of symphalangism is discussed.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
5/7. Middle ear adenoma. A tumor displaying mucinous and neuroendocrine differentiation.Middle ear adenoma (MEA) is a distinctive, rare entity that appears to be derived from the lining epithelium of the middle ear mucosa. We report four cases of MEA displaying the typical histologic growth pattern. Two distinct tumor cell immunophenotypes were identified in all cases; the first type exhibited positivity with anti-epithelial membrane antigen and anti-keratin antibodies, and the second type showed immunoreactivity with anti-keratin, anti-vimentin, and anti-neuron-specific enolase antibodies. Ultrastructural studies revealed bidirectional mucinous and neuroendocrine differentiation, demonstrated by the presence of two distinct cell types containing apically located mucous granules and basally concentrated neuroendocrine granules, respectively. The presence of neuroendocrine differentiation was supported by the immunohistochemical detection of vasoactive intestinal polypeptide in the tumor cells in one case and neuron-specific enolase in three cases. These findings suggest that the potential for mixed mucinous/neuroendocrine differentiation described in other endodermally derived tumors also exists in middle ear mucosa. We also believe that the rare lesions diagnosed as primary carcinoid tumors of the middle ear might in fact be MEA with predominant or only neuroendocrine differentiation. The clinical course of our four cases and our review of the pertinent literature confirm the benign nature of MEA and indicate that these tumors should be treated by complete local excision without additional therapy.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
6/7. hearing loss in Hunter's syndrome--mucopolysaccharidosis ii.Hunter's syndrome [mucopolysaccharidosis ii (MPS II)] is a genetic, metabolic disease of excessive mucopolysaccharide storage leading to mental and skeletal abnormalities, distinctive facial features, and increased incidence of hearing loss. However, the hearing impairment in MPS II has not been well described in the literature. This paper examines the auditory aspects of MPS II by reviewing the literature and by presenting two affected brothers. Each subject had mixed hearing disorders, fluctuating between moderate and severe degrees associated with recurrent middle ear effusions. hearing loss appears to be a frequent concomitant of MPS II and is usually of mixed nature. The conductive component may persist after myringotomy. Aggressive audiological and otological management are required to enhance communicative development.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
7/7. Misdiagnosis of hearing loss due to ear canal collapse: a report of two cases.Collapse of the external auditory meatus during audiometry can lead to spuriously increased hearing thresholds being obtained, particularly at high frequencies, and may simulate conditions such as noise-induced hearing loss, presbyacusis and retrocochlear pathology. Consequently, inappropriate investigations and management may be undertaken. Two patients with elevated thresholds secondary to ear canal collapse are described. The implications of initially failing to identify the true nature of their 'hearing losses' are highlighted and strategies to avoid such pitfalls are discussed.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |