Biomedical subjects
Publications and source records attributed to E T Ajax.
We describe a 60-year-old man with MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) and discuss the mitochondrial DNA point mutation 3243. A diagnosis of MELAS should be considered in the appropriate clinical setting at any age.
Progressive, sequential visual loss in the left and then right eye was reported in a 73-year-old male over three months. The presence of a family history of visual loss and the lack of other findings in association with bilateral cecocentral scotomata led to a diagnosis of new onset Leber's hereditary optic neuropathy, confirmed by the presence of a mutation at the 11,778 position. This case illustrates that Leber's hereditary optic neuropathy may manifest late in life.
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A patient with bilateral trochlear nerve palsies is presented. Computed tomographic (CT) brain scan localized an anterior cerebellar vermis lesion compressing the area caudal to the inferior colliculi where the fourth nerves decussate and exit the dorsal brain stem. This lesion was probably responsible for the bilateral trochlear nerve dysfunction. Pertinent anatomy and pathologic involvement are discussed.
Unilateral visual neglect is a common symptom or sign in patients with lesions of the nondominant hemisphere. Several techniques have been used to demonstrate visual neglect. One such technique--asking a patient to bisect a horizontal line and expecting an estimate of center away from the side neglected--has been used for over 70 years but has not been statistically evaluated. We conducted a formal evaluation of this method and found that under special conditions, line-bisection performance can discriminate between patients with right-hemisphere lesions and patients with diffuse lesions, patients with left-hemisphere lesions, and hospital controls. When used to investigate visual neglect in an individual patient, the line-bisection test should be given in conjunction with other complementary procedures such as symmetric drawings and the Memory-for-Designs Test.
We postulate that palatal myoclonus after infarction of the brainstem or cerebellum, or both, is the manifestation of denervation supersensitivity secondary to lesions involving the dentatorubroolivary system. Two cases of our own and 31 from the English and French literature were analyzed in order to determine the delay between the occurrence of presumed anatomical lesions and the recognition of palatal myoclonus. The intervals varied from 2 to 49 months with the median between 10 and 11 months. The natural history of palatal myoclonus following brainstem infarction seemed consistent with the hypothesis.
A patient who had alexia without agraphia, right homonymous hemianopia, and intact color-naming was studied anatomically. Pathologic involvement of the splenium and related forceps was restricted to the inferior third, supporting published suggestions that inferior elements of this commissure and left peristriate cortex may be essential to the decoding to the written word, while color-naming may be functionally aligned to more dorsal elements.
The selective inability to comprehend the spoken word, in the absence of aphasia or defective or defective hearing, is defined as pure word deafness (auditory verbal agnosia). Reported cases of this rare disorder have suggested the site of involvement to be strategically placed, interrupting fibers from left and right primary auditory receptive areas which project to Wernicke's are in the dominant hemisphere. Our patient is a 44-year-old male who suffered from an uncertain illness complicated by fever, jaundice and generalized seizures seven years previously. Following an apparent convulsion, the patient was noted to be unable to understand spoken language without loss of ability to recognize and respond to sounds or marked impairment of speech or reading. The evidence suggested bilateral cerebral hemisphere disease more marked on the right. The abrupt onset without progression is consistent with a vascular or ischemic etiology. Conclusions about the nature of the lesion and areas involved must await further studies and ultimately tissue examination.
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