Proliferation of large protoplasmic astrocytes results in atypical cells such as Opalski cells and Alzheimer cells.
Presence of such astrocytes is a pathological feature of:
E. Wilson’s disease is also known as hepatolenticular degeneration. It is an autosomal recessive disorder of copper metabolism.The abnormal gene (ATP7B) is located in chromosome 13. Ceruloplasmin is an α2 globulin that normally carries 90% of the copper present in the plasma. In Wilson’s disease, ceruloplasmin fails to bind copper and its excretion by the liver is impaired. The excess copper accumulates first in the liver and then in the brain (especially putamen and pallidus) and other tissues. In the early stages of the disease, proliferation of large protoplasmic astrocytes, such as Opalski cells and Alzheimer cells, occurs. Deposition of copper in Descemet’s membrane in the cornea leads to the appearance of the golden-brown ‘Kayser–Fleischer’ (KF) ring. The main neurological abnormalities are rigidity, dystonia,chorea, athetosis, dysarthria, and tremor. It is considered that a pure psychiatric presentation occurs in 20–25% of cases. Around 50% of patients will have mental disturbances at some point during the course of the disease. Psychiatric manifestations tend to occur more commonly with neurological forms of Wilson’s disease than with the hepatic form of the clinical syndrome. Cognitive impairment occurs in up to 25% of patients. The dementia is usually subcortical type with frontal deficits. Depression occurs in 30% of cases and suicidal behaviour may occur in between 4 and 16%.
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Which of the following statements regarding the teratogenic effect of alcohol on neuronal development is false?
E. It has been postulated that exposure of the brain to alcohol during the period of rapid synaptogenesis (third trimester) leads to apoptosis and neuronal loss, especially in thalamic and basal ganglia area. Since this change is apoptotic, it does not lead to fibrous scarring. This apoptotic cell death has been postulated to be due to the action of alcohol on the NMDA and GABA receptors. Apparently, large quantities of alcohol taken during a short period of time, even once, as in a binge episode, can lead to these changes. The cluster of symptoms also depends on the timing of alcohol exposure, so if the exposure occurred during the first trimester it would lead to facial abnormalities. In addition to developing hyperactivity/attention deficit disorder and varying degrees of learning impairment in children, a high percentage have adult-onset neuropsychiatric disturbances, including major depression and psychosis. There is no evidence to suggest that thiamine deficiency mediates neuronal damage in fetal alcohol syndrome.
Features of the cauda equina syndrome include all except:
C. Cauda equina syndrome is characterized by low back pain (radicular pain), asymmetric weakness, areflexia, and sensory loss in the legs, and relative sparing of bowel and bladder function. The syndrome usually results from injury of multiple lumbosacral nerve roots within the spinal canal. Most commonly, this is due to a ruptured lumbosacral intervertebral disc (disc prolapse). Less common causes include lumbosacral spine fracture, haematoma within the spinal canal, and compressive tumours. Cauda equine must be differentiated from conus medullaris syndrome, which includes compression of the lower sacral and coccygeal segments. This results in bilateral saddle anaesthesia, prominent bladder and bowel dysfunction, and impotence. Cutaneous refl exes are absent, but the muscle strength is usually preserved in conus medullaris syndrome.
Which of the embryonic germ cell layers give rise to neurones?
D. During embryonic development, gastrulation leads to the formation of the germ layers—ectoderm, mesoderm, and endoderm. Skin and nervous system develops from the ectoderm, the gut from the endoderm, and all other visceral organs from the mesoderm. After gastrulation, the notochord is formed from mesodermal cells. This notochord lies rostro caudally and it sends signals to the ectoderm lying adjacent to it, transforming them into neurectoderm. This forms the neuronal stem cells in the embryo. This strip of ectoderm is otherwise called the neuronal plate. By the third week of gestation, a groove develops on the dorsal aspect of the neural plate and this groove gradually deepens, forming neuronal folds. These folds gradually close bidirectionally by the end of the fourth week, forming the neural tube. Closure of the neural tube is susceptible to teratogenic influences operating in first trimester (e.g. valproate).
All of the following are features of lesion to the cerebellum except:
E. Sphincter disturbance is not a feature of isolated cerebellar lesions. Unilateral lesions of the cerebellum affect ipsilateral limbs. Symptoms of cerebellar damage include asynergia (loss of coordination between muscles leading to jerky movements), dysmetria (defects in reaching targets via crude motor movements, for example past pointing on finger–nose test), intention tremor, dysarthria, disturbed balance including gait ataxia (produces wide-based, staggering gait prone to shuffle or fall), hypotonia, dysdiadochokinesia (inability to do rapid alternate movements), and nystagmus. The cerebellum has been suggested to be a seat of cognitive function, especially working memory.
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