Deafness deficits

Mitochondrial diseases may be manifest as ready fatigability elevated lactic acid levels In blood Increased muscle enzymes In serum ataxia and a variety of neurosensory deficits. Including blindness and deafness. 

The earliest clinical deficits include numbness and tingling sensation of the lips, hands and feet, joint pain, narrowing of vision, hearing difficulties, a widely based gait, and emotional disturbances. These symptoms arise from whole-blood concentrations of mercury that exceed 200 pg Hg 1 of whole blood (normal concentration, 1-8 pg Hgl ). The progression of symptoms includes incoordination, difficulty in pronouncing words, deafness, emotional disturbances, and ultimately, death. 

Previous observations have shown that most patients who develop aseptic meningitis or encephalitis due to LCMV recover completely. No chronic infection has been described in humans, and after the acute phase the virus is cleared. However, as in all infections of the central nervous system, particularly encephalitLs, temporary or permanent neurological damage is possible. Nerve deafness and arthritis have been reported. Infection of the human fetus during the early states of pregnancy may lead to developmental deficits that are permanent. 

The systems mainly involved are auditory, motor and intellectual. The language deficit results from a combination of deafness and intellectual deficit, as well as defective motor control of speech. The motor deficit is characterized by predominantly proximal rigidity and spasticity that implies extra-pyramidal more than pyramidal dysfunction. 

Clinical data indicate that the major deficits in neurological cretinism are intellectual deficiency, deafness, and motor rigidity, and indicate that the parts of the nervous system most affected are the cerebral neocortex, the cochlea, and the basal ganglia. The findings implicating basal ganglia disease have generally received little attention. 

Approximately 50Z of the sample were currently hypothyroid. Studies of median and tibial somatosensory evoked potentials showed minimal disturbances. Peripheral conduction studies unexpectedly showed only minor abnormalities, despite the fact that some individuals have been severely myxoedematous for decades. 56% of those patients tested had evidence of hearing deficit. Analysis of BAERs pointed to a peripheral cause of deafness. 

Cyanides are rapidly metabolised in the body and recovery is possible if continued exposure is ceased. Long-term effects of acute exposure may lead to intellectual deficit, unsteady gait, Parkinsonism, deafness and post-traumatic stress disorder. 

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