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Neuropathology Flashcards

1
Q

Head injury: types, outcomes

A

Penetrating injury
Crush injury
Deceleration injury (most common)

==> damaged depends on the energy of impact (mass and velocity)

Possible outcomes:

  • skull fractures
  • parenchymal injury
  • vascular injury
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2
Q

Skull fractures: types, signs

A

Linear fracture = bursting fracture (crack skull)
Depressed fracture = skull depressed inward into the parenchyma, usually comminuted (several pieces)

Fracture of skull base

  • often indicates severe head injury
  • difficult to visualise in plain Xray –> use CT
  • signs (tearing of dura resulting in CSF leakage)
  • -> anterior cranial fossa fracture = CSF rhinorrhoea, raccoon eye (periorbital ecchymosis)
  • -> petrous temporal bone fracture = CSF otorrhoea, battle sign (mastoid ecchymosis)

Note: fatal head injuries don’t always have fracture

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3
Q

Primary brain injuries: parenchymal injury - types, definitions, appearance of contusion and diffuse axonal injury, outcomes

A

Concussion

  • clinical syndrome of altered consciousness secondary to head injury
  • complete neurological recovery but retrograde amnesia

Direct parenchymal injury (grey matter)

  • laceration: penetration of object and tearing of tissue
  • contusion: bruise due to blunt trauma (mostly at frontal and temporal lobes, base of brain –> haemorrhagic lesions on top of gyri, disrupt pia arachnoid)
  • coup injury: contusion at point of contact
  • countercoup injury: contusion on brain surface diametrically opposite to it e.g. fall backwards –> frontal/temporal lobe contusion

Diffuse axonal injury (white matter)

  • commonly rotational type injury causing tearing of axons
  • -> axonal swelling (histo: axonal balls)
  • -> focal haemorrhage e.g. corpus callosum, cerebellar peduncles, dorsal brainstem
  • major cause of prolonged comatose state
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4
Q

Primary brain injuries: traumatic vascular injury (types, origin of bleed, clinical features, severity, causes)

A

Haematoma = collection of blood
MUST BE EXCLUDED!! (by CT imaging)

Epidural haematoma

  • origin: middle meningeal artery
  • features: LUCID INTERVAL (tough dura withstands pressure initially) –> subsequent rapid neurological deterioration (coma, rapid collection of blood – emergency!)
  • convex shape in CT
  • commonly due to fracture temporal bone

Subdural haematoma

  • origin: bridging vein between dura and arachnoid membrane/superior sagittal sinus
  • MC SOL in acute head injury!
  • features: acute = life threatening or chronic = may cause dementia
  • causes: minor HI especially in elderly with brain atrophy, rapid change in head velocity (differential movement of brain and skull)
  • crescent shape on CT (crosses suture lines)

Cerebral haematoma

  • origin: intracerebral vessels; contusion injury
  • contusion very big that it reaches cerebral hemispheres
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5
Q

Primary brain injuries: spinal cord injury - cause, signs, management

A

Associated with transient or permanent displacement of the vertebral column e.g. hyperflexion, hyperextension

Signs:

  • conscious
  • respiratory compromise if above C4
  • paraplegia if involve T vertebrae or below
  • urinary retention if S2-S4

Management

  • vertebra stabilisation
  • chronic care
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6
Q

Secondary brain injuries (much more important and serious!!)

A

Sequelae of primary injury leading to further damage and neurological deterioration

Cerebral oedema
Hydrocephalus
Raised intracranial pressure and herniation

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7
Q

Secondary brain injuries: cerebral oedema - definition, pathways of formation, pathology (4), consequences/sequence of events

A

Accumulation of excess fluid within brain parenchyma

Pathways of oedema formation:

  • vasogenic oedema – BBB disruption and increased vascular permeability = increase ECF
  • cytotoxic oedema – generalised hypoxic and ischaemic insult = increase ICF

Pathology of generalised oedema

  • flattened gyri
  • narrowed intervening sulci (almost absent)
  • compressed ventricular cavities
  • herniation

Consequences:
- intracranial haematoma –> mass effect –> increase ICP

==> decrease CPP (CPP = MAP - ICP) –> decrease CBF –> cerebral ischaemia –> further oedema and raised ICP

==> brain shift –> brain herniation –> brainstem compression

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8
Q

Secondary brain injuries: Hydrocephalus

A

Accumulation of excessive CSF within ventricular system

  • communicating = ventricular system in communication with subarachnoid space –> entire ventricular system enlarged
  • non-communication/obstructive = ventricular system obstructed –> enlarge certain ventricles
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9
Q

Secondary brain injuries: raised ICP and herniation - signs of raised ICP, types of herniation and their effects

A

Signs of raised ICP

  • papilledema (optic disc swelling)
  • headache, projecting vomiting without nausea
  • sinus bradycardia, hypertension (widened pulse pressure), irregular breathing
  • herniation

Herniation = displacement of brain tissue past rigid dural folds or openings

  • **Uncal/transtentorial herniation
  • uncus (medial temporal lobe) through tentorium cerebelli (into brainstem)
  • features: TRIAD –> fixed pupil dilation (CNIII parasympathetic supply lost), hemiplegia (cerebral peduncle), coma (midbrain RF and PCA)

Tonsillar hernation

  • cerebellar tonsils through foramen magnum (into upper cervical canal and medulla)
  • features: respiratory arrest and BP instability (medulla) –> death

Central herniation

  • downward pressure centrally
  • features: LR palsy (CNVI traction), bilateral uncal herniation

Subfalcine hernation

  • cingulate gyrus through falx cerebri
  • features: compression of ACA and its branches

Unchecked supratentorial pressure leads to downward displacement of brainstem and cerebellum –> stretch perforating branches of posterior circulation in circle of willis = brainstem haemorrhage = death

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10
Q

Implications of Head injury for clinical management: GCS, ICP, swelling, hypoxia and mass lesion

A

Glasgow coma scale (GCS)

  • neurological function most important!!
  • assessment of conscious level in response to defined stimuli
  • eye response (max 4), verbal response (max 5), motor response (max 6)
  • 15 = best response; <8 = comatose; <3 totally unresponsive
  • monitoring and prognostic implication (>14 = 0.4% mortality; 9-13 = 4%; <8 = 45%)

Close monitoring of raised ICP (to AVOID HERNIATION AND COMA)

  • intraventricular ICP monitoring
  • external ventricular drainage
  • emergency Burr hole
  • CPP = MAP - ICP (aim ICP <20 mmHg and CPP >60 mmHg)

Reduce cerebral swelling e.g. mannitol, furosemide
Evacuate mass lesion (CT scan to screen)
Prevent hypoxia/hypercapnia (vicious cycle with oedema)

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11
Q

CNS tumours: epidemiology, clinical presentations, grading

A

Children

  • most common solid cancer in children (overall 2nd after leukaemia)
  • medulloblastoma is most common type

Adults
- most common type (60%) = glioblastoma multiforme

Clinical presentations

  • headache (60%), seizure (>30%)
  • ssx of raised ICP – usual cause of death
  • focal neurological deficits
  • malignant tumours usually don’t metastasise outside the brain (except medulloblastoma)

Grading
- WHO (low grade: I, II; high grade III, IV)

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12
Q

Glioma: nature, types

A

Except pilocytic astrocytoma, all other gliomas:

  • are potentially malignant
  • transform from low grade to high grade lesion within years

Astrocytoma

  • infiltrating astrocytoma: diffuse –> anaplastic –> glioblastoma multiforme
  • pilocytic astrocytoma

Oligodendroglioma (rare)
Ependymoma (rare)

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13
Q

Parenchymal tumours: types (4), associated effects

A

Primary CNS lymphoma

  • 80-90% B cell origin
  • without co-existing systemic lymphoma
  • a/w HIV and EBV

Vestibular schwannoma (acoustic neuroma)

  • benign tumour of CN VIII at cerebellopontine angle
  • deafness

Pituitary adenoma

  • most common is non-functioning (then PRL/GH)
  • mass effect, hypopituitarism, visual effects, headaches

Arteriovenous malformation
- may cause cerebral haemorrhage or SAH

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14
Q

Metastatic tumours: 2 types, common primaries

A

Cerebral metastasis

  • lung most common, breast (long latent period), colorectal, thyroid, melanoma
  • good survival with chemo

Meningeal metastasis

  • lymphoma, leukaemia
  • always check CSF during treatment!
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15
Q

Astrocytoma: origin, for each type (grade, nature, age group, common sites, pathology features, prognosis)

A

Origin: astrocytes

Diffuse astrocytoma

  • grade II
  • malignant, in adults
  • pathology: local hypertrophy, DIFFUSE INFILTRATION with poorly defined margins (incurable by surgery and high recurrence)
  • **Glioblastoma multiforme
  • grade IV
  • malignant, in adults (MC primary brain cancer)
  • common site: corpus callosum (butterfly lesion)
  • pathology: NECROSIS with fibrillary process, ENDOTHELIAL PROLIFERATION of tumour capillaries with poorly formed BBB (contrast enhancement on imaging)

Prognosis of infiltrating astrocytomas:

  • 5-7 yrs with treatment (diffuse type)
  • may progress to anaplastic type (grade III, 2-3 yrs) and GBM (12-18 mths)

Pilocytic astrocytoma

  • grade I
  • benign, in children
  • common site: cerebellum, 3rd ventricle, cerebrum
  • pathology: well circumscribed cystic lesion with enhancing MURAL NODULE; bipolar spindle cells and bluish material
  • prognosis: doesn’t progress
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16
Q

Other gliomas: oligodendroglioma and ependymoma (origin, nature, age group, common sites, pathology features, prognosis)

A

Oligodendroglioma

  • origin: oligodendrocytes
  • benign, adults
  • common site: cerebrum
  • pathology: CALCIFICATIONS seen on CT, CLEAR VACUOLATED CELLS
  • prognosis: transform to anaplastic oligodendrogliomain 7-10 yrs (slow growing, better prognosis)

Ependymoma

  • origin: ependymal cells (line ventricles)
  • benign, children
  • common sites: 4th ventricle, spinal cord (MC tumour of spinal cord parenchyma)
  • pathology: perivascular pseudorosettes
  • prognosis: transform to anaplastic ependymoma in 5-7 yrs; treatment difficult due to poor chemoRT response
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17
Q

***Medulloblastoma: origin, nature, age group, common sites, pathology features, prognosis

A

Origin: primitive cells
Malignant, most common solid tumour in children

Common site: vermis (cerebellum) – protrude into 4th ventricle (infiltrate brainstem)

Pathology: ROSETTES, small round blue cell tumour

Prognosis: METASTASIS possible to CSF, bone etc; 60-80% survival with treatment

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18
Q

**Meningioma: origin, nature, age group, common sites, pathology features, prognosis

A

Origin: arachnoid cells
Benign (grade I), adults

Common sites: EXTRA-CEREBRAL e.g. brain surface, superior sagittal sinus, spinal cord, skull base

Pathology: attached to dura mater, MENINGOTHELIAL WHORLS (nuclei wrap around themselves), Psammoma bodies

Prognosis: 10-15% recurrence

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19
Q

CNS germinoma: origin, nature, age group, common sites, pathology features, prognosis

A

Origin: germ cell (MC GCT of brain)
Malignant, children

Common sites: midline e.g. pineal gland

Pathology: identical to dysgerminoma of ovary and seminoma of testis

Prognosis: may spread to CSF; 90% cure with RT

20
Q

Cerebrovascular disease definition, classification of infarcts

A

Injury to brain as a consequence of altered blood flow –> cerebral infarction or cerebral haemorrhage

Stroke = clinical term for acute onset of neurological deficits resulting from haemorrhage or obstructive vascular lesions

Classification of infarcts

  • ischaemic necrosis of the brain (example of liquefactive necrosis)
  • large vessel disease vs small vessel disease
  • thrombosis vs embolism
  • focal ischaemia vs global ischaemia
21
Q

Cerebral infarct - Large vessel disease: distribution, pathogenesis, presentations

A

Distribution

  • *embolism: MCA (MC; most of cerebral surfaces), ACA (medial surface of cerebral hemispheres), PCA (inferior surface of hemispheres and posterior hemisphere)
  • thrombosis: MC outside brain at carotid bifurcation (cartoid bruit), vertebrobasilar artery; less common inside brain at internal carotid, MCA

Pathogenesis
- atherosclerosis (thrombosis and embolism), other causes of embolism e.g. IE/valvular disease (vegetation), AF, patent foramen ovale, drug abuse (heroin, cocaine)

Presentations: territorial infarcts

  • -> MCA: contralateral hemiparesis, sensory loss in face and upper extremity, expressive aphasia, visual field defects, head and eyes deviate to side of lesion
  • -> ACA: contralateral hemiparesis, sensory loss in lower extremity
  • -> vertebrobasilar system: vertigo, ataxia, ipsilateral sensory loss in face, contralateral hemiparesis and sensory loss in trunk and limbs
22
Q

Cerebral infarct - Small vessel disease: distribution, pathogenesis, presentations

A

Most common ischaemic stroke
Distribution
- mostly thrombotic
- perforators of major branches in Circle of Willis e.g. lenticulostriate arteries (from MCA at base of brain)
- lacunar infarcts - <15 mm at deep grey matter e.g. thalamus, IC, caudate nucleus, pons

Pathogenesis
- arteriosclerosis (HT)

Presentations (lacunar infarct)
- asymptomatic
- purely sensory loss (thalamus)
- purely motor loss (posterior limb of IC - also sensory?)
- mixed if larger
- little alteration of consciousness
- normal CT or MRI (<2cm hypodensity)
- transient ischaemic attack (recovery <24 hrs)
- may lead to multi-infarct dementia
(cerebral haemorrhage)
23
Q

Cerebral infarct - classification by cause

A

Focal ischaemia due to thrombosis or embolism (large and small vessel disease)

Global ischaemia/ hypoxia due to circulatory collapse, epilepsy, severe hypoglycaemia –> sudden death
- hippocampus most vulnerable (esp CA1; loss of neurons seen histologically)

24
Q

Cerebral infarct - pathology: <48hrs, 48 hrs-days, 10 days-3wks (macroscopic and microsopic)

A

<48 hrs

  • Macroscopic
  • -> little change in first 6 hrs – nothing on CT/MRI but still important to image and rule out haemorrhage
  • -> acute SWELLING (loss of grey-white differentiation) and herniation
  • -> thrombotic = PALE infarct (no reperfusion)
  • -> embolic = haemorrhagic infarct (with reperfusion at later stage)
  • Microscopic
  • -> RED NEURONS: acute injury and subsequent apoptosis causing pyknosis and karyolysis –> EOSINOPHILIC
  • -> acute inflammation: NEUTROPHILS, oedema

48hrs-3 wks
- Microscopic: REACTIVE GLIOSIS
–> microglial cells (MACROPHAGES) engulf/lyse myelin and blood if present
–> astrocytes (REACTIVE GLIAL CELLS) with cellular processes form glial fibres at edge of infarction, taking up the role of fibroblasts
==> liquefaction and calcification of old infarct

10 days-3wks

  • Macroscopic: gelatinous and friable tissue (days), LIQUEFACTIVE NECROSIS (wks)
  • -> loss of tissue and fluid-filled cavity; wedge-shaped
  • -> full pattern after a few months
  • -> hypodense SOL on CT
25
Q

Intracerebral haemorrhage: definition, causes and related pathology, common sites

A

Definition = haemorrhage within the brain due to rupture of a small intra-parenchymal vessel
–> HYPERDENSE SOL on CT

  • *Causes
  • HT
  • -> MC factor a/w DEEP BRAIN parenchymal haemorrhage (basal ganglia, thalamus)
  • -> pathology: hyaline arteriosclerosis, Charcot-Bouchard aneurysms (microaneurysmal outpouchings)
  • Cerebral amyloid angiopathy
  • -> MC factor a/w LOBAR haemorrhage
  • -> commonly involving superficial cortical vessels of occipital and parietal lobes
  • -> a/w Alzheimer’s disease
  • -> pathology: brittle vessels with palely eosinophilic material impregnated on vessel wall
  • Haematological: thrombocytopenia, leukaemia (too many WBC makes vessels bleed easily)
  • Tumours: glioma (high grade), metastasis (melanoma, RCC) – also lobar haemorrhage
  • Vascular: AVM
  • “Congenital”: ruptured berry aneurysm
  • Drug: thrombolytics

Common sites:

  • BASAL GANGLIA (most common)
  • thalamus
  • cerebellum
  • lobes of brain, brainstem
26
Q

Subarachnoid haemorrhage: causes, pathogenesis and site of MC cause, complications, clinical presentations

A

Bleeding into subarachnoid space (basal cisterns)

Causes

  • ANEURYSM
  • AV malformation
  • -> BERRY aneurysm most common: due to HT; structural defects of media and elastica develop over time; connective tissue disease e.g. Marfan’s
  • -> 90% found in arterial branch points of anterior circulation in Circle of Willis - AComm branch MC
    (note: if aneurysm is very large, it can bury into cerebral parenchyma and burst –> cerebral haemorrhage instead of SAH)
  • -> Fusiform atherosclerotic aneurysm (basilar artery)
  • -> Infective mycotic aneurysm (SBE)

Complications:
- Early phase
= vasospasm cause irritation to basal cisterns –> additional ischaemic injury (1/3 mortality)
= cardiac arrhythmia due to brainstem hypoxia

  • Healing phase
    = rebleeding
    = hydrocephalus (organisation of haematoma occluded CSF outflow)

Clinical presentations:

  • Sudden onset of severe occipital headache (“worst headache ever”)
  • nuchal rigidity due to irritation of meningeal membranes
27
Q

Dementia - definition, what is MCI

A

Group of diseases characterised by DECLINE IN COGNITION involving one more cognitive domains. causing ADL impairment

Memory –> early presentation of Alzheimer’s disease
Language, Behavioural –> early presentation of Fronto-temporal dementia
Behavioural, Executive function –> early presentation in vascular dementia
Visual spatial

Late presentations: depression, hallucination, delusion, agitation, withdrawal

Mild cognitive impairment (MCI) = between cognitive changes of aging and early dementia – ADL not substantially interfered

28
Q

Dementia - primary and secondary causes

A

Primary causes:

  • **Common
  • Alzheimer’s disease (70%)
  • Vascular dementia (20%)
  • Parkinson’s disease (small proportion)
  • Fronto-temporal dementia

Less common
- MS, ALS, Creutzfeldt-Jakob disease, Parkinson-plus syndrome

Secondary causes:

  • CNS - chronic subdural haematoma, brain tumours, normal pressure hydrocephalus
  • Iatrogenic - drugs, alcoholism, Vit B12 deficiency
  • Hypothyroidism
  • Psychiatric disorders
  • HIV infection
29
Q

Alzheimer’s disease - epidemiology and risk factors

A

Most common cause of dementia

Risk factors:

  • Sporadic type
  • -> age (>80)
  • -> apoE allele (epsilon 4; higher risk than 3 or 2)
  • Familial early onset type(<1% cases; AD inheritance, a/w Down’s syndrome)
  • -> amyloid precursor protein (APP) mutations on chr 21
  • -> presenilin (PS1 & PS2) mutations on chr 14 and 1
30
Q

Alzheimer’s disease - pathology: gross morphology (2), histology (3) and pathogenesis for each abnormality, staining

A

Gross morphology (non-specific)

  • cerebral ATROPHY: narrowed gyri, widened sulci, decreased brain weight
  • VENTRICULAR DILATION secondary to decrease in brain volume

Histology

  • NEURITIC PLAQUES and NEUROFIBRILLARY TANGLES
  • -> normally seen in the brains of elderly but exaggerated in AD
  • -> HIPPOCAMPUS most commonly affected

Neuritic plaque

  • EXTRACELLULAR amyloid core surrounded by dystrophic neurites (dilated, tortuous)
  • pathogenesis –> abnormal cleavage of APP at cell membrane = POLYMERISATION OF A-BETA PEPTIDES (aggreggation)
  • staining: silver stain, congo red stain, Ab against A-beta

Neurofibrillary tangles

  • INTRACELLULAR tau-containing irregular twisted filaments in cytoplasm
  • pathogenesis: HYPERPHOSPHORYLATION OF TAU protein (alters cytoskeleton microtubules in neuron = cells die)
  • staining: silver stain, Ab against tau

CEREBRAL AMYLOID ANGIOPATHY

  • amyloid (almost identical to A-beta in neuritic plaques) present in cerebral vessels
  • weakening of vessels increases risk of haemorrhage
  • staining: Ab against A-beta, congo red
31
Q

Alzheimer’s disease - clinical presentations and treatment

A

Clinical:

  • early: loss of smell, NO focal neurological deficits
  • late: changes in behaviour, judgement, language

Treatment:

  • cholinesterase inhibitors improve memory and reduce hallucination; S/E bradycardia e.g. donepezil
  • NMDA inhibitor for moderate to severe diseases e.g. memantine
32
Q

Vascular dementia: associated syndromes, clinical presentation

A

Group of syndromes including

  • multi-infarct dementia i.e. repeated strokes (especially if sub temporal gyrus affected) – stroke increases risk of mental impairment by 4-5x
  • subcortical infarcts (damage white matter)
  • Binswanger disease: diffuse white matter disease (due to chronic arteriosclerosis and poor perfusion of small vessels)
  • -> leukoaraiosis: demyelination of white matter particularly in periventricular region (shrinking and scarring seen as radiolucency on imaging)

Clinical presentation
- STEPWISE DECLINE in cognition in multi-infarct dementia (symptoms stay same for a while then suddenly decline)

33
Q

Parkinson’s disease: pathogenesis, pathology, prevalence of dementia, cause of dementia and core features, clinical presentation of Parkinson’s

A

Not primary related to dementia!!

Hypokinetic movement disorder due to degeneration of dopaminergic neurons in substantia nigra (depigementation)

Pathology: LEWY BODY (alpha-synuclein inclusion in neurons; lewy neurites), TAU PROTEIN

Dementia in 10-15% patients due to:
- Alzheimer’s disease
- Dementia with Lewy body (DLB) –> Lewy body spreading from brainstem to cerebral cortex
==> core features: PARKINSONIAN features, fluctuating levels of ALERTNESS, visual HALLUCINATIONS

Clinical presentations

  • cogwheel rigidity
  • bradykinesia: masked face
  • resting tremor (pill rolling)
  • postural instability, stooped posture
  • gait: difficulty in initiating first step, shuffling gait
34
Q

Fronto-temporal dementia: definition, age affected, how to distinguish from AD, pathogenesis and associations

A

50-70 yrs old
Heterogenous set of disorders a/w focal degeneration of frontal and/or temporal lobes

Distinguished from AD:

  • alterations in personality, behaviour and language PRECEDE MEMORY LOSS
  • no focal neurological deficits (same as AD)

Pathogenesis and associations:

  • C9ORF72 (chr9) mutation – accumulation of TDP-43; a/w ALS
  • MAPT (ch17) mutation – accumulation of TAU (PICK BODIES); a/w Parkinsonism
35
Q

Prion disease: nature, pathogenesis, examples of disease, causes, typical morphology, clinical presentation

A

Rare
Prions = infectious proteins without nucleic acids
– “infectious”: protease-resistant misfolded PrP promotes conversion of normal PrP to protease-resistant PrP
– can’t be killed with standard sterilisation techniques
– can stain with Ab (IHC), western blot

Transmissible spongiform encephalopathy/ Creutzfeldt-Jakob disease

  • early old age
  • TRANSMISSION through electrodes, dura mater graft (direct inoculation to brain), ingestion from infected cattle (bovine spongiform encephalopathy/ mad cow disease)
  • SPONGIFORM – “bubble and holes” change in cerebral cortex and deep gray matter structures (microscopic vacuoles
  • ENCEPHALOPATHY – subacute dementia, myoclonic jerks, characteristic EEG changes with periodic spikes, death <1 yr
36
Q

Screening tests for dementia

A

MMSE and AMT for late stage dementia
HKMoCA for early stage dementia
Modified Barthel index for assessing ADL impairment

37
Q

Diseases of skeletal muscles - common causes, characteristics

A

Main causes in adults

  • usually inflammatory (part of autoimmunity)
  • neurogenic diseases
  • dystrophy
  • metabolic disease

Characteristics

  • no obvious neurological causes
  • symmetrical and diffuse
  • no associated sensory loss (presence of sensory loss = peripheral neuropathy)
  • adult vs paediatric: early onset
  • patterns of muscle weakness
    • proximal weaker than distal
    • face-sparing e.g. LGMD, DMD/BMD
    • face involvement e.g. FSHD
38
Q

Diseases of skeletal muscles - investigations

A

Inflammatory/auto-immune markers: ESR, antibodies

CK-MM isoenzyme: specific to skeletal muscle

Electromyography (EMG)

Muscle biopsy: definitive diagnosis for difficult cases; examined in transverse section (need snap freezing)

DNA studies

39
Q

Inflammatory Myopathy: causes, age group, pathology, clinical presentation, associations, investigations, treatment

A

Polymyositis, dermatomyositis, necrotising autoimmune myopathy

Acquired, most common in adult/middle age
Pathology: large number of inflammatory cells migrating and damaging muscles

Clinical presentation: proximal muscle weakness and tenderness (symmetrical)

Associations:

  • systemic autoimmune disease
  • STATINS
  • HIV
  • paraneoplastic disease (especially dermatomyositis)

Investigations

  • high ESR, CK
  • **EMG: polyphasic units
  • autoimmune Ab

Treatment: steroids, cancer surveillance (especially dermatomyositis)

40
Q

Degenerative myopathy: classical example, pathogenesis, clinical presentations, pathology, treatment

A

Amyotrophic lateral sclerosis/ motor neuron disease

  • insidious onset
  • neuronal loss at ALL LEVELS OF MOTOR SYSTEM (cortex, brainstem and anterior horn cells)
  • -> usually LMN first then UMN

Clinical presentations:

  • LMN signs
  • -> skeletal muscle weakness (asymmetric) and atrophy (extensors more affected)
  • -> bulbar palsy: dysphagia, dysphasia
  • -> respiratory muscle paralysis: death in 3-5 yrs
  • UMN signs
  • -> spasticity, Babinski sign
  • Extraocular muscles, bowel/bladder muscles and sensory functions spared (parasympathetic system preserved)
  • some familial cases associated with fronto-temporal dementia (TDF-43 accumulation) but otherwise cognition is normal

Pathology:
- no inflammation, reduction in number of anterior horn cells neurons

Treatment:
- Riluzole (glutamate release inhibitor)

41
Q

Dystrophies

A

Primary muscle diseases

Duchenne/Becker muscular dystrophy
Limb-girdle muscular dystrophy
Facioscapulohumeral dystrophy

42
Q

Duchenne/ Becker muscular dystrophy: pathogenesis and genetic aberration, diagnosis, clinical presentations, pathology, prognosis

A

Pathogenesis:

  • Deletions (MC) or duplications of Dystrophin gene (Xp21 - X-linked disease)
  • dystrophin acts as anchor for actin to adhere to plasma membrane allowing efficient transmission of signals
Duchenne = out-of-frame mutations ==> total truncation of protein
Becker = in-frame mutations ==> milder disease

Diagnosis:

  • muscle biopsy: dystrophin IMMUNOSTAINING (nothing on DMD, little on BMD)
  • DNA studies: western blot
  • other labs: CK very high at birth and decreases as muscles degenerate; also higher in female carriers

Clinical presentations: (male)

  • symptoms occur before 5yrs old (delayed motor milestones e.g. difficulty in running/rising)
  • weakness and wasting of PELVIC muscles: GOWER’s SIGN, waddling gait, toe-walking, lumbar lordosis
  • CALF pseudohypertrophy due to FIBROSIS AND INFILTRATION OF MUSCLE TISSUE BY FATTY TISSUE (thigh muscles not strong enough)
  • CARDIOMYOPATHY: heart failure, arrhythmia
  • intellectual impairment (30%)

Pathology: increase connective tissue replacing myofibres

Prognosis: DMD death by 20s, BMD by 40-50s

43
Q

Limb-girdle muscular dystrophy (LGDM) - inheritance, pattern of weakness, age group affected

A

AD or AR
Facial sparing, involving limb girdle (scapula/arms + pelvic/thighs)
Early or adult onset

44
Q

Facioscapulohumeral dystrophy (FSHD): genetics, muscle involvement

A

> 1 form of disease
- one of which is AD deletion of repeat DNA sequences at chromosome 4q

Muscle involvement

  • facial muscles
  • upper and distal limbs: scapular winging
  • pelvic girdles preserved
45
Q

Floppy infant syndrome: definition, SMA (genetics, types), mitchondrial myopathy (genetics, a/w, examples, pathology), metabolic myopathy (causes)

A

Generalised hypotonia in newborn

Spinal muscular atrophy (SMA)

  • AR deletions of SMN1 gene –> atrophic fibre GROUPS (failed development)
  • type I (infantile) most common: floppy baby syndrome, CANNOT SIT UNSUPPORTED (Werdnig-Hoffman disease)
  • type II (intermediate) and type III (juvenile)

Mitochondrial myopathy

  • maternally transmitted diseases, gene deletions most common
  • usually a/w brain degeneration
  • examples: MELAS, progressive external ophthalmoplegia
  • pathology: RAGGED RED FIBRES using special stain (at rim of myofibres); EM accumulation under sarcolemma

Metabolic myopathy

  • symptomatic only with exercise or fasting
  • glycogen storage disease, lipid storage disease (myofibres stained with lipids which can’t be metabolised)

Other causes: congenital muscular dystrophy/myopathies, perinatal asphyxia

ACP (27 decks)

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