Peripheral Neuropathies and ALS Flashcards
Mononeuropathy
Focal involvement of a single nerve
Examples of mononeuropathy
Median: Carpal tunnel Ulnar: cubital tunnel Radial: wristdrop Peroneal: foot drop (compression, trauma or entrapment)
Mononeuropathy multiplex
Damage to one or more peripheral nerves (at random and noncontigous)
Pattern early on is asymmetric
Polyneuropathy
Several peripheral nerves affected at same time
Presents as distal and symmetric deficit
How to classify the problem
(based on structure affected)
Axon (axonal or neuronal)
Myelin (demyelinating)
Most common neuropathy
Diabetic polyneuropathy
Neuropathy
Axon is target
May see motor and sensory deficits but SENSORY usually precedes motor
Neuronal neuropathy
Affects nerve cell bodies in anterior horn of spinal cord or dorsal root ganglion
Examples of neuronal neuropathy
Type 2 Charcot Marie tooth hereditary
Vitamin B6 toxicity
Demyelinating neuropathies
Involve myelin sheath surrounding axon
Often autoimmune or inherited (Guillain Barre, chronic inflammatory demyelinating polyneuropathy or charcot marie tooth)
What is Guillain Barre Syndrome?
Idiopathic inflammatory neuropathy
Demyelinating
When do you see Guillain Barre more
After infection (campylobacter jejuni!!)
Presentation of Guillain Barre Syndrome
Ascending weakness (symmetric) usually beginning in legs
Sensory usually
Absent DTRs frequently
Maybe autonomic dysfunction
What is chronic inflammatory demyelinating polyneuropathy?
Idiopathic inflammatory neuropathy (slowly progressive or relapsing)
Presentation of CIDP
Diffuse hyporeflexia or areflexia
Diffuse weakness
Generalized sensory loss
What is Charcot-Marie-Tooth?
Hereditary motor and sensory neuropathies (genetically heterogenous group of disorders with similar clinical phenotype)
Presentation of Charcot Marie Tooth
Weakness
Wasting of distal muscles in limbs (with or without sensory loss)
Pes cavus
Reduced or absent DTRs
Timing types
Acute (days to 4 wks)
Subacute (4-8 wks)
Chronic (>8 wks)
Cause of acute mononeuropathy
Probably traumatic or ischemia
Cause of chronic mononeuropathy
-More common
Entrapment or recurrent minor trauma
Cause of acute polyneuropathy
Think inflammatory process (Guillain-Barre, neoplasms, infection, toxins)
Cause of chronic polyneuropathy
Hereditary or metabolic, CIDP (gradual evolution over yrs)
Peripheral vs motor vs sensory nerves
Peripheral: sensory, motor and autonomic elements
Motor: large myelinated fibers
Sensory: large for proprioception and small for pain and temp
Sxs associated with motor nerve problems
Weakness
Fatigue
Cramps
Muscle twitches
Signs of motor nerve problems
Weakness
Muscle wasting
Fasciculations
Sxs associated with sensory nerve probs
Numbness or loss of sensation
Altered sensation
Neuropathic pain (burning, dull, poorly localized or sharp)
Loss of coordination/imbalance
Signs of sensory nerve probs
Sensory loss (sharp/dull, light touch, temp, vibration etc) Loss of proprioception
First thing to be lost in pts with polyneuropathies
Ankle reflexes
Autonomic sxs
Postural hypotension Tachycardia Cold extremities Impaired thermoregulatory sweating Bowel and bladder dysfunction Impotence
Example of chronic axonal polyneuropathy
Diabetes
History seen with chronic axonal polyneuropathies
Sxs begin in LE
Sensory sxs usually before motor
Slowly progressive, dysesthesias, mild gait probs
Stocking glove distribution
PE for chronic axonal polyneuropathies
Distal loss of sensation to pin prick, light touch, vibrations, temp or proprioception
May see muscle wasting of feet or lower leg
Hypoactive or absent reflexes
Most common acute demyelinating polyneuropathy
Guillain Barre
History seen with acute demyelinating polyneuropathy
Mostly affecting motor nerve fibes
Weakness is usually the early sign
Dysesthesias distally later on
May have gait difficulties or hand clumsiness
PE with acute demyelinating polyneuropathy
Generalized weakness (distal muscles) Abnorm vibratory and proprioception (out of proportion to loss of pin prick or temp sensation)-mostly large myelinated fibers
Myopathy vs neuropathy
Myopathies have PROXIMAL motor weakness while neuropathies have DISTAL motor weakness (if any sensory loss or change in reflexes than neuropathy)
Radiculopathy
Different distributions of motor and sensory deficits (segmental pattern)
Neck or back pain that radiates to extremities in radicular distribution is probably root lesion
B12 deficiency
Symmetrical neuropathy (LEGS more than arms) Paresthesias and ataxia first with loss of vibration and proprioception
Motor neuron diseases
Sxs of upper and/or lower motor neuron dysfunction WITHOUT sensory sxs
What can electrodiagnostic testing do?
Differentiate axonal or demyelinating in character
See is primary nerve or muscle disorder
Nerve conduction study
Permit conduction velocity to be measured in motor and sensory fibers
Electomyography
May show denervation of affected muscles
Tx of Guillain Barre
Plasmapheresis and IVIG
No steroids!!!!
Tx of CIDP
Steroids and IVIG (consider plasma exchange)
Pharm tx for neuropathic pain
NSAIDs (mild)
*Gabapentin, pregabalin, TCAs
Maybe duloxetine, venlafaxine or carbamazepine
Most common form of motor neuron disease
Amyotrophic lateral sclerosis (ALS)
Presentation of ALS
Relentlessly progressive, incureable neurodegenerative disorder (muscle weakness and disability)
Mixed upper and lower motor neuron deficit in limbs
Normal sensory exam!!
Usually presents in 1 of 4 body segments (cranial/bulbar, cervical, thoracic and lumbosacral) and then spreads
Involuntary muscle wasting and weight loss
PE to distinguish lower and upper motor neuron
Lower: weakness, atrophy, muscle cramps, hypo-reflexia, fasciculations!
Upper: slowness, incoordination, increased tone, hyperreflexia, spasticity, clonus
How to diagnose ALS
Clinically (NCS normal, EMG might show diffuse ongoing chronic denervation)
Median survival of ALS
3-5 yrs (survival beyond 20 very rare)
