931-4. Convergence Insufficiency. History.
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A 73-year old man with known PD for 10 years, complained of horizontal double vision for 18 months. He could see the images move apart and refocus a single image by blinking. Diplopia was most marked reading, driving and watching TV. Three ophthalmologists gave him 3 separate sets of glasses. Past hx –ve for strabismus or prism glasses.
Tremor of the hands at rest
Slow hypometric saccades
Saccadic substitution for smooth pursuit
Poor visual suppression of the vestibular ocular reflex
Decreased spontaneous blink rate
Glabella tap positive
Rigidity of the neck, head flexed and tilted
Mild head tremor
Slow (akinetic) head and neck movements
Spinocerebellar Ataxias (SCA), especially SCA2 (olivopontocerebellar atrophy)
Progressive Supranuclear Palsy
Parkinson’s (advanced cases) and related diseases.
Amyotrophic Lateral Sclerosis (some cases)
Drug intoxications: anticonvulsants, benzodiazepines
Courtesy of Mendez F. Cummings JL. Dementia: A Clinical Approach. Third Edition. Butterworth Heinmann 2003.
The brain MRI
Pathology of the midbrain
are taken from the case of an elderly woman with Parkinson’s Disease.
Figure 1 Axial T2WI through the midbrain shows the normal pars compacta, the space between the substantia nigra and red nuclei.
Figure 2 Axial T2WI in a patient with PD shows the midbrain is atrophic and the red and substantia nigra almost touch each other because the pars compacta is greatly reduced.
Courtesy Anne Osborn, MD
Figure 3 Axial gross autopsy in patient with PD shows striking reduction of the pars compacta, especially well seen on the right side where the red nucleus and substantia nigra are actually touching
Figure 4 Section of the brain showing cytoplasmic inclusion body within a surviving neuron with an eosinophilic core surrounded by a clear halo. The Lewy body is not entirely specific, but it is a highly sensitive marker for PD
Due to dopaminergic cell death leading to dopamine deficiency
Defective gene for synuclein on Chr. 4q
Second locus on Chr. 2p