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Extra Information!. Dayna Ryan, PT, DPT Winter 2012. Classification of Nerve Injuries. Neurapraxia = segmental demyelination, which slows/blocks conduction of the action potential
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Extra Information! Dayna Ryan, PT, DPT Winter 2012
Classification of Nerve Injuries • Neurapraxia = segmental demyelination, which slows/blocks conduction of the action potential • Axonotmesis = when axon is damaged but the connective tissue coverings that support and protect the nerve remain intact • Neurotmesis = complete severance of the axon and supporting connective tissues
Classification of Neuropathy • Mononeuropathy: single peripheral nerve affected (i.e. CTS) • Polyneuropathy: multiple peripheral nerves involved (i.e. DM) glove/sock • Radiculoneuropathy: involvement of the nerve root as it emerges from the spinal cord (dermatome/myotome) • Myopathy: muscle involved, typically at NMJ
Saturday Night Palsy/Sleep Palsy • Radial nerve compression (typically is spiral groove of the humerus) • Compression causes segmental demyelination • Radial nerve compression in the axilla: crutch palsy • Clinical presentation: weakness in triceps, brachioradialis, and supinators, wrist extensors, and grip; paresthesias in the radial nerve distribution
Erb’s Palsy = traction injury to the brachial plexus at birth • Erb-Duchenne Palsy: C5-C6 nerve roots • Klumpke’s Palsy: C8-T1 nerve roots • Whole Arm Palsy: C5-T1 nerve roots
Morton’s Neuroma • Entrapment of the common digital nerve • Most often occurs in the third toe space • Symptoms: burning/tingling/sharp pain, always want to massage foot
Carpal Tunnel Syndrome • Impingement of the median nerve AT THE WRIST (carpal tunnel) • Cubital tunnel syndrome = ulnar nerve impingement at the elbow
Thalamic Pain Syndrome = results when a stroke occurs in the thalamus • Initial Symptom: numbness on the opposite side of the body • Later develops into burning/tingling sensation • Allodynia (hypersensitivity to pain) • Pain can increase from ambient temperatures (heat or cold) or emotional distress • SENSORY affected!
Reye’s Syndrome • Exact cause is unknown • Seems to be triggered by using aspirin to treat a viral illness or infection (flu, chicken pox) in children/teens who have an underlying fatty acid oxidation disorder • Exposure to certain toxins: insecticides, herbicides, paint thinner • Blood glucose drops while levels of ammonia (acidity) rise • Liver swells and develops fatty deposits • Brain may swell seizures, convulsions, LOC
Reye’s Syndrome • Initial signs/symptoms • Children <2 y.o.: diahrrea, rapid breathing • Older children/teens: persistent vomiting, lethargy/unusual sleepiness • Additional signs/symptoms • Irritability; aggressive/irrational behavior • Confusion, disorientation, or hallucinations • Weakness or paralysis in the arms/legs • Seizures • Excessive lethargy • Decreased level of consciousness
Spinal Muscular Atrophy • Lesion site = anterior horn cells and motor nuclei of the brainstem • Etiology: autosomal-recessive inheritance • Signs/Symptoms: • Hypotonia • Weakness • Cranial nerve palsies
Spinal Muscular Atrophy • Proximal muscles are weaker than distal • Good fine motor control • Legs weaken before arms • Only motor system affected • Decreased DTRs • Hypotonia • Weakness/atrophy
Spinal Muscular Atrophy • SMA Type I (Werdnig-Hoffman Disease) = floppy baby syndrome • Never sit, roll, walk • Death by 3 y.o. from respiratory failure • SMA Type II • Onset before 18 months of age • May sit but never walk • Death by 7 y.o.
Spinal Muscular Atrophy • SMA Type III (Kugelberg-Welander Disease) • Onset after age 2 • Difficulty walking, running, jumping • Half of these children lose the ability to walk by age 10 WC dependent as adults • Proximal muscle weakness but affects UE more • Can have either hyporeflexia or hyperreflexia
Blood-Brain Barrier = specialized, permeable barrier between the capillary endothelium of the CNS and extracellular space • Exclude large molecules (FFA, proteins, specific amino acids) • Prevents many pathogens from entering CNS