Peripheral Neurological Syndromes Flashcards
Mechanical radiculopathy General description Focal / diffuse? Onset Age Risk factor Cause Cellular pathology
Numbness, paresthesias, or pain (usually radicular). Radicular pain may be reproduced in the leg by the straight leg test.
Focal
Acute
Age – middle / elderly.
Risk factor – spondylosis
Cause – spinal nerve root compression from disc herniation (sudden) or spondylosis (gradual onset)
Cellular pathology - ischemic injury to myelin / axons or direct injury from compression. May see demyelination.
Idiopathic Facial Neuropathy Other name General description Focal / diffuse Onset Cause Prognosis
Bell’s Palsy
Includes weakness / plegia, hyperacusis (weak stapedius), diminished taste, or diminished lacrimation.
Focal
Subacute
Cause – inflammation due to a virus (often HSV) is common. Others include compression, infarction of facial nucleus, or inflammation from Lyme disease.
Usually resolves over weeks / months.
Mechanical mononeuropathy General description Focal / diffuse? Onset Age Risk factors Pathology
Numbness, parasthesias, or pain, w/ or w/o motor / sensory loss, of a single nerve. Compression more common than trauma. Atrophy may be present. Shaking the limb often improves sxs (does not occur in CNS).
Focal
Gradual
Age – usually young adults / middle aged
Risk factors – polyneuropathy, increased connective tissue volume (may be due to pregnancy), poor ergonomics, and family history of mechanic mononeuropathy
Pathology – Possible demyelination w/ or w/o axonal loss at site of compression. Ischemic injury to myelin / axons. Possible direct mechanical disruption.
• Hypothyroidism may cause increase in connective tissue → tightness of tunnel → ulnar nerve entrapment
Vestibular Schwannoma Description Focal / diffuse? Onset Age Risk factors Pathology
Slow growing tumor on CN VIII. Gradually progressive unilateral hearing loss.
Focal
Gradual
Age – middle / elderly
Risk factors – radiation exposure and neurofibromatosis type II (causes bilateral Schwannomas)
Microscopic pathology – spindled cells resembling fibroblasts arranged in whorls.
Trigeminal neuropathy Description / cause Triggers Focal / diffuse? Onset Pathology
- Episodic unilateral facial pain w/ unknown cause
- Secondary has a cause: compression of nerve root such as neoplasm / inflammation (commonly occurs w/ MS)
- Facial pain is often described as lancinating (stabbing) or electric
- Attacks may be triggered by somatosensory stimuli to teeth, inner cheek, or face
- Facial sensory loss may occur
- Focal
- Onset is usually sudden (over seconds) and episodic
- Pathology – demyelination of small axons where CN V enters pons. Demyelination may allow for ephaptic (nonsynaptic) transmission to occur, w/ non-nociceptive axons being conducted into nociceptive axons.
Guillain Barre Syndrome Other name Description Focal / diffuse? Onset Cause Prognosis Age Risk factors
- Acute inflammatory demyelinating polyradiculoneuropathy
- Ascending weakness of the legs, arms, face, and diminished reflexes (starts in legs). May cause paraspinal / radicular pain from spinal nerve root inflammation or cause limb / gait ataxia from loss of position sense. Risk of respiratory problems.
- Diffuse
- Subacute
- Caused by autoimmune demyelination via attack on Schwann cell. Involves both cellular and humoral autoimmunity. May involve complement Ig deposition.
- Usually resolves over weeks / months. Usually only occurs once.
- Age – young adults / middle aged
- Risk factors – Campylobacter jejuni gastroenteritis (strong). Viral infection (weak).
General sxs of polyneuropathy
Disequilibrium due to lack of proprioception. Symmetric distal motor loss. Length-dependent (toes go first). Stockings and gloves pattern.
Diabetic polyneuropathy Description Focal / diffuse? Onset Population Pathology
- Most common cause of polyneuropathy. Polyneuropathy + possible autonomic dysfunction, retinopathy, nephropathy, accelerated atherosclerosis .
- Diffuse
- Gradual
- Most commonly affects middle aged, men more than women.
- Pathology – nonenzymatic glycation of molecules that disrupts normal metabolism → direct injury to neurons and Schwann cells.
Charcot-Marie-Tooth Disease Description Focal / diffuse? Onset Age Risk factor Pathology
- Gradually progressive polyneuropathy caused by mutations. May have enlarged nerves, high arches, hammertoes, and distal tapering of leg bulk (stork legs). Affects legs and hands (stocking / gloves). Lose bulk in hands as well.
- Diffuse
- Gradual
- Starts in children and progresses through life.
- Risk factor – family history of CMTD.
- Pathology – hypertrophic demyelination w/ onion bulb formation.
Autoimmune myositis General description Focal / diffuse? Onset Cause Prognosis Population Risk factors 3 main types Pathology
- Diffuse skeletal muscle inflammation → symmetric proximal limb weakness
- Diffuse
- Gradual
- Cause – cellular autoimmune attack on skeletal myocytes or skeletal muscle blood vessels.
- May be static or improve over months
- Affects middle age / elderly, women more than men.
- Risk factors – cancer (strong), family history of autoimmunity (weak)
- Polymyositis – only diffuse myositis
- Dermatomyositis – diffuse myositis + autoimmune rash
- Heliotrope rash – symmetric purple discoloration of eyelids and periorbital tissue, w/ or w/o edema
- Inclusion body myositis – asymmetric distal / proximal weakness, often w/ disproportionate involvement of finger flexors and knee extensors. May have myocytes w/ inclusions or irregular cytoplasmic vacuoles w/ granular degenerated material such as beta-amyloid.
- Pathology – lymphocytes (then macropahges) infiltrate skeletal muscle → necrosis w/ possible focal fibrosis. Dermatomyositis may involve complement Ig deposition.
Duchenne Muscular Dystrophy General description Focal / diffuse? Onset Cause What does dystrophin normally do? Treatment
Proximal limb weakness. May involve CHF, scoliosis, and static cognitive impairment since birth. Waddling gait due to weakness of hip abductors.
Diffuse
Gradual
Mutation in dystrophic gene on X chromsome.
Dystrophin gene normally aids in structural stability of myocyte by connecting the contractile apparatus of myocte w/ ECM.
Don’t do strength exercises. Using muscles makes problems worse. Therapy usually involves stretching.
Myasthenia gravis Focal / diffuse Onset Signs in thymus Population Pathology
Diffuse
Episodic
Thymic hyperplasia / thymoma may be present.
Mainly affects young adults / middle aged. More women than men.
Pathology - The number of Ach receptors is reduced due to Ab binding → endocytosis / destruction of Ab-receptor complex.
