Peripheral Neuropathies Flashcards
Polyneuropathy
Symmetrical distal sensory loss with burning or weakness.
Med rxn or systemic dz
Can be axonal or demyelinating
Guillain-Barre Syndrome (GBS)
Acute immune-mediated group of polyneuropathies, usually provoked by preceding infection.
GBS Patho
Acute inflammatory demyelinating polyneuropathy (AIDP)
Can be caused by preceding infxn, immunizations, surgery
Generation of antibodies against galgliosides that cause an immune response against axons
Which bug usually causes GBS?
Campylobacter Jejuni
also CMV, EBV
GBS clinical features
Symmetrical muscle weakness Decreased DTR's Respiratory involvement Parasthesias in hands and feet Severe back pain
Where does weakness usually start in GBS?
Proximal legs, arm and facial muscles
Dysautonia
Common in GBS
Tachycardia, urinary retention, HTN altering with Hypotension, bradycardia, ileus, loss of sweating.
Therapy for GBS?
Plasmapheresis or IVIG
GBS DIagnosis
LP: Elevated protein
Neurophysiology studies
Bell’s Palsy
Acute peripheral facial palsy of unknown origin
Involves the facial nerve (CN VII)
What does the facial nerve innervate?
Facial motor output
Parasympathetics to salivary glands (including lacrimal)
Taste for anterior 2/3 of tongue
Somatics for EAC and pinna.
Bells palsy Epidemiology
Risk 3x greater in pregnancy
DM is risk factor
Recurrence is common
Bells palsy patho
Herpes virus most likely cause
Can also be other viruses
Ischemia may play a role
Bells palsy clinical presentation
Sudden onset over hours**
Eyebrow sagging, cant close eye
Mouth drawn to non-affected side
Decreased tearing**
Bells palsy course
Onset over hours to 1-2 days
Maximal paralysis within 3 wks of onset
Some degree of recovery by 6 months
Usually recover fully
Bells Palsy Mgmt
Eye care (drops)
Glucocorticoid therapy within 3 days of onset
For severe, valcyclovoir
Myasthenia Gravis (MG)
Autoimmune disorder characterized by weakness and fatiguability of skeletal muscle.
Decrease in number of acth receptors
What are the antibodies against in MG?
Acetylcholine receptors (AchR-Ab)
MG Patho
Acetylcholine receptor antibodies mount immune response via complement against receptors.
T cells bind receptors and activate B cells.
Which thymus abnormalities do MG patients usually have?
Thymoma or hyperplasia
MG Bimodal distribution
Females peak in 2nd and 3rd decade
Males peak in 6th to 8th decade
MG Clinical Manifestations
Fluctuating skeletal muscle fatigue worsened by contractile force. Ptosis, worse w/ upward gaze Diploplia Weakness with prolonged chewing Dysphagia
MG Neck and Limb Symptoms
Dropped head syndrome from weak neck
Limb proximal weakness Arms > Legs
MG respiratory sx
Respiratory muscles weaken and leads to respiratory failure
MG Course
Symptoms ok in morning, worse later in day
Maximal extent of dz seen in 3 yrs
MG Dx
Detect circulating AChR-Ab
Electromyography
MG Tx
Pyridostigmine
Corticosteroids
IVIG
Thymus surgery
Polyneuropathy Causes
Diabetic polyneuropathy most common
AIDS, B12 def, Toxins, Uremia
Polyneuropathy Patho
Axonal injury is most common
Demyelinating seen in some autoimmune processes
Polyneuropathy Presentation
Slowly progressive loss of sensation in feet 1st
Dysesthesias, burning, pain
Gait abnormalities
Stocking and glove weakness
Risk factors for diabetic polyneuropathy (DPN)
Duration and severity of hyperglycemia Increased triglycerides Increased BMI Smoking HTN
Diabetic Polyneuropathy Patho
Accumulation of AGE’s, collagen cross-linking, increased permeability, monocyte influx, vascular injury.
Accumulation of sorbitol, interferes w/ cell metabolism.
Axonopathy
What is the most common neuropathy in the western world?
Diabetic neuropathy.
50% of DM pts will develop
DPN S/S
Loss of vibratory sensation and proprioception
IMpaired pain, light touch and temp perception
Decreased/absent DTRs
Widespread losses are a late finding
Best pain reliever for Polyneuropathy
Gabapentin (Neurontin)
Best pain reliever for Diabetic PN
Pregabalin (lyrica)
Other meds for Polyneuropathy
Gabapentin (Neurontin) TCA's (amitryptaline) Carbamazepine (Tegretol) - varying success Pregabalin (lyrica) - Diabetics Duloxetine (Cymbalta)
Alcoholic Polyneuropathy Patho
Axonal neuropathy complicated by demyelination with coexisting nutritional deficiency
Normal thiamine status
Alcohol is direct neurotoxin
Vitamin B12 Deficiency
Cobalmin
Must have adequate dietary intake and intrinsic factor
B12 Patho
Defect in myelin formation leads to subacute degeneration of dorsal and lateral spinal columns.
S/S of B12 Def.
Parasthesias, ataxia, loss of proprioception, weakness, spasticity, clonus, paraplegia
B12 Tx
IM B12 injections 1000mg twice weekly
VItamin E deficiency
Spinocerebellar syndrome
Seen in pancreatic deficiency, cholestasis
Vitamin E deficiency tx
Large oral doses of IM Alpha-Tocopherol
then daily oral vitamin E
Thiamine Deficiencies
Seen in malnutrition, alcoholism, bariatric surgery
Dri or wet Beriberi
Dry beriberi
Neuropathy associated with calf cramps, muscle tenderness, burning feet, autonomic neuropathy may be present.
Wet beriberi
High output CHF and neuropathy
