Neuropathology 2 Flashcards
(28 cards)
What is demyelination?
Destruction of myelin sheath surrounding axon, with relative preservation of axons themselves
What is the purpose of myelin?
Insulation- allows rapid conduction of electrical impulses along cell membranes
How is demyelination classified?
Primary
Secondary
Metabolic
Toxic
The aetiology and pathogenesis of MS are not fully understood, what factors have been implicated however?
Environmental
Genetic
Immune
What appearance does the brain and spinal cord have in MS
External appearance is usually normal, when surface is cut reveals multiple areas of demyelination called plaques
What is the distribution of plaques?
Any site in CNS, commonly seen in CN II, Periventricular white matter, corpus callosum, brainstem and spinal cord
What are the 4 types of MS plaques?
Acute active
Chronic (Inactive)
Chronic active
Shadow
What is an active plaque?
Evidence of ongoing myelin breakdown with abundant macrophages
What is an inactive plaque
Centre contains little or no myelin, astrocytic proliferation and gliosis are prominent
What are shadow plaques?
Border between normal and affected white matter not clear, some abnormally thinned out myelin sheaths can be identified especially at outer edges.
How do acute plaques appear?
Demyelinated plaques are yellow/brown, with an ill defined edge which blends into surrounding white matter
How do chronic plaques appear?
Well demarcated grey/brown lesions in white matter, classically situated around lateral ventricles.
What are the 3 main features of MS histologically?
Demyelination
Inflammation - Perivascular with oedema
Gliosis- Astrocytic gliosis prominent feature in MS
What is dementia?
Impairment of occupational or social functioning due to development of memory impairment, associated with impairment of intellectual function
What are the primary dementias?
Alzheimers
Lewy body
Huntingtons disease
Pick’s disease
What are the secondary dementias?
Disorders resulting in secondary changes in CNS resulting in dementia eg vascular, metabolic, infection and trauma
What is the macroscopic features of Alzheimers?
Cortical atrophy Widening sulci Narrowed Gyri Compensatory dilation of ventricles Frontal temporal and parietal lobes affected Brainstem and cerebellum normal
Microscopic features of Alzheimer’s
Intracytoplasmic neurofibrillary tnagles
Amyloid angiopathy
Amyloid plaques
Extensive neuronal loss with astrocytosis
What are the hallmarks of lewy body dementia?
Hallucinations and fluctuating level of attention
Fluctuation in severity on day to day basis
What are the pathological features of LBD?
Degeneration of substantia nigra
Remaining nerve cells contain lewy bodies
Degeneration of cortical areas
Lewy bodies can be detected by immunochemical staining for Ubiquitin protein
What are the symptoms of Huntington’s disease
Chorea, myoclonus, clumsiness, slurred speech, depression, irritability and apathy
Which gene is affected in huntingtons
Huntingtin gene of chromosome 4p
Histological appearance in Huntington’s?
Loss of neurones in caudate nucleus and cerebral cortex, accompanied by reactive fibrillary gliosis
What is Pick’s disease?
Progressive dementia commencing in middle life (50 to 60), slowly progressing changes in character and social deterioration leading to impairment of intellect, memory and language
