Limb weaknesses etc Flashcards
causes of slowly progressinge proximal weakness
Inflammatory myopathies: dermatomyositis, inclusion body myositis, polymyositis
Muscular dystrophies: Duchenne’s (X-linked disorder, affects muscle membrane protein dystrophin). Thyroid myopathies, toxic and iatrogenic myopathies (statin-induced, alcohol related and steroid induced).
Myasthenia gravis: autoimmune isease, distinguishing feature – fatiguability with exercise, Ach receptor-binding antibodies in the blood.
Amyotrophic lateral sclerosis.
Proximal weakness with prominent muscle atrophy suggests what ddx?
muscular dystrophy, cachectic myopathy, MND
do neuromuscular junction disorders affect muscle bulk?
No
lesions wehere produce spasticity?
in the pyramidal system. clasp knife
lesions where produce rigidity?
in the extrapyramidal system. increase in tone is independent of velocity nad direction of movement
flacidity occurs when lesions are where>?
PNS lesion or hyperacute CNS (Stroke, spinal shock)
causes of rapidly progressing acute weakness
Guillain Barre syndrome
Myasthenic crisis
Brainstem catastrophe
Botulism
Causes of sensory polyneuropathy:
Diabetes
B12 deficiency
Monoclonal gammopathy – Igs formed from a single circulating clone of plasma cells. Associated with multiple myeloma. Neuropaites associated tih monoclonal gammopathy:
Length-dependent axonal polyneuropathy
POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes)
Anti-MAG (myelin-assocaited glycoprotein)
Amyloidosis
Vasculitis (but ususually causes MM) EtOH CMT HIV Thyroid dysfunction
Iatrogenic: chemotherapy (cisplatin), amiodarone, chloroquine, colchicines, metronidazole, phenytoin
Idiopathic
screening panels for common causes of sensory polyneuropa
HBA1c, and OGTT TSH B12 levels (+homocysteine + methylmalonic acid if B12 low or borderline) Serum protein electrophoresis, urine protein electrophoresis Blood urea, nitrogen, creatinineALT, AST HIV antibodies ESR Antinuclear antibody
What is lateral medullary syndrome?
Also known as wallenberg’s syndrome; it is caused by a brainstem stroke in the territory of the vertebral or posterior cerebellar artery
Clinical features:
Ipsilateral signs: Horner’s syndrome, nsystagmus, facial sensory impairment, ataxia, diplopia
Contralateral signs: pain and temperature loss over opposite arm and trunk (spinothalamic tract)
findings of cerebellar synd
General
Intention tremor
Neurological
Ataxic gait, truncal ataxia, hypotonia, pendular reflexes, dysmetria, dysdiadochokinesis, nustagmus, slurred speech, heel-shin ataxia
Extras
Cause: fractures of multiple sclerosis (spastic parapareis, sensory disturbance, INO)
Features of chronic alcoholism (liver disease)
Friedreich’s ataxia (young patient, wheelchair/walking aids, pes cavus, kyphoscoliosis, absent ankle jerks with up-going plantars)
causes of cerbellar syndrome
Multiple sclerosis Alcoholic cerebellar degeneration Posterior fossa space-occupying lesion Brainstem vascular elsion Inherited ataxias (Friedreich’s) Paraneoplastic syndromes Drugs (phenytoin)
how to differentiate the site of cerebellar
The cerebellum is divided into midline vermis nad two cerebellar hemispheres
Disease of the vermis leads to truncal ataxia and ataxic gait
Disease of hemisphere cuases ipsilateral dysmetria, dysdiadochokinesis, intention tremor, fast-beat nystagmus towards the lesion
MS (demyelination) cuases a global deficit.
What is Friedreich’s ataxia:
Autosomal recessive, trinucelotide repeat on chromosome 9/
Degeneration of the spinocerebellar tract causes cerebellar signs
Corticospinal tract damage and peripheral nerve degeneration lead to absent ankle jerks with extensor plantars
Pes cavus, scoliosis and diabetes are common features, others include cardiomyopathy, cataracts and sensorineural deafness.
what is myotonic dystrophy
Autosomal dominant, trinucleotide repeat disorder showing genetic anticipation (expansion of an unstable CTG repeat in the myotonic protein kinase gene). Gene located on chr19
