Peripheral Nerve Disorders Flashcards
Polyneuropathy
sensory, motor or mixed deficit affecting more than one peripheral nerve simultaneously
Mononeuropathy
sensory, motor or mixed deficit affecting a specific nerve
Mononeuropathy Multiplex
sensory and/or motor deficits affecting single nerves in different, unrelated parts of the body
Radiculopathy
disease of the spinal nerve roots
Plexopathy
sensory and/or motor deficit involving
the lumbar or brachial plexus
Amyotrophy
pathological wasting of muscles due to a disease of the nerves supplying them
Charcot-Marie-Tooth (3)
- HMSN I & II
- Usually autosomal transmission
- Short arm of chromosome 17 (or 1 or X)
Charcot-Marie-Tooth Presentation (5)
- Foot deformities or gait disturbances in childhood
- Distal weakness and wasting starts in the legs
- Variable distal sensory loss
- Depressed or absent tendon reflexes
- Tremor is sometimes present
What are the phenotypes for Charcot Marie Tooth? (4)
– High arches (pes cavus)
– Calf muscle wasting
– Barrel chest
– Distinctive walk
Outcome of Charcot Marie Tooth (2)
- EMG, NCS shows marked reduction in both sensory and motor conduction
- Despite the neuropathy, these patients can live long, productive lives (orthotics help)
Dejerine-Sottas Dz (5)
- HMSN III
- Onset in infancy or childhood
- Motor and sensory polyneuropathy
- Peripheral nerves may be palpable
- Segmental demyelination, Schwann cell hypertrophy and thin myelin sheaths
Inherited Neuropathies (5)
– Charcot-Marie-Tooth – Dejerine-Sottas – Fredrich Ataxia – Refsum disease – Porphyria
Neuropathies a/w Systemic and Metabolic Disorders (4)
– Diabetic
– Uremic
– Alcohol and nutritional deficiency
– Paraproteinemias
Infectious and Inflammatory Neuropathies (6)
- Leprosy,
- AIDS,
- Lyme disease,
- Sarcoidosis,
- Polyarteritis,
- RA
Fredreich Ataxia (6)
– Chromosome 9
– Onset in childhood
– Gait is ataxic, Hands are clumsy, Other signs of cerebellar dysfunction
– Weakness in the legs, but primarily a sensory neuropathy (dorsal root ganglia, dorsal and lateral columns)
– Depressed DTRs
– Upgoing Babinski’s
Refsum Dz (6)
- HMSV IV
- Autosomal recessive disorder
- Disturbance in phytanic acid metabolism
- Pigmentary retinal degeneration
- Progressive sensorimotor polyneuropathy, cerebellar signs, auditory dysfunction, cardiomyopathy, cutaneous manifestation
- Dietary reduction in phytanic acid, plasmapheresis
Diabetic Peripheral Neuropathy Overview
• Peripheral neuropathy – Distal symmetric polyneuropathy – Isolated peripheral neuropathy – Painful diabetic neuropathy – Diabetic neuropathic cachexia • Autonomic neuropathy
Distal Symmetric Polyneuropathy (5)
- Most common type
- Due to an axonal neuropathic process
- Longer nerves are most vulnerable (foot)
- Motor and sensory nerves
- Achilles reflexes may be absent
Sensory Distal Symmetric Polyneuropathy(4)
– decreased sensation to vibration, pain and temperature
• Painful
• Progressive in severity and distribution
• Examination with monofilament picks up patients who are at risk for unperceived neuropathic injury
Motor Distal Symmetric Polyneuropathy (3)
- denervation of the lumbricals in the feet -> clawing of the toes, anterior displacement of the submetatarsal fat pads -> increased plantar pressure
• Neuropathic injury results from decreased pain sensation, increased plantar pressures and repetitive stress (walking)
• Charcot foot
Distal Symmetric Polyneuropathy Tx (5)
• Treatment of ulcers: – Revascularization if possible ** – Unloading – Treat infection – Debride if necessary • Recurrence should be minimized by wearing appropriate footwear, checking the feet daily
Isolated Peripheral Neuropathy
- Sudden onset with later recovery of all or most of the function
- Attributed to vascular ischemia or traumatic damage
- Cranial and femoral nerves are commonly involved
- Predominantly motor abnormalities
Isolated Peripheral Neuropathy Presentation (6)
– Diplopia: involvement of CN III, IV, OR VI
• Pupil is spared
• Full recovery in 6-12 weeks
• Severe pain in the anterior thigh (unilateral)
• Within days muscle wasting and weakness
• As weakness appears, pain improves
Isolated Peripheral Neuropathy Tx (2)
- Analgesia, better control of diabetes
* Symptoms improve over 6-18 months
Painful Diabetic Neuropathy (2)
- Hypersensitivity to light touch
* Severe burning pain (nocturnal)
Painful Diabetic Neuropathy Tx (6)
– Amitriptyline – Tricyclic antidepressants (TCA) – Gabapentin • Improvement in 48-72 hours is usual • Improves sleep • Discontinue medication if no improvement in 5 days
Diabetic Neuropathic Cachexia (4)
- a/w profound weight loss
– Painful dysesthesias affecting the proximal lower limbs, the hands or the lower trunk
– Treatment is insulin and analgesia
– Prognosis is good with recovery of weight and cessation of pain within one year
Autonomic Neuropathy Overview (6)
- Postural hypotension
- Decreased cardiovascular response to valsalva
- Gastroparesis
- Diarrhea/constipation (IBS)
- Inability to empty the bladder
- Impotence
Postural Hypotension (3)
– Thigh high compression stocking
– Sleeping semi-recumbant
– Fludricortisone or midodrine
Gastroparesis (2)
– Can present as pain, bloating, and vomiting following meals
– Can present as fluctuations in blood sugar following meals
Gastroparesis Tx (4)
– Metaclopramide can be used for treatment **
– Erythromycin binds to motilin receptors in the stomach
– Botox injections at the pylorus
– Implanted gastric electric stimulators
Diarrhea (7)
– Broad-spectrum antibiotics – a/w impaired sphincter control and fecal incontinence – Loperamide – Diphenoxylate with atropine – Paregiroc – Codeine – Clonidine
Constipation (4)
- Usually responds well to stimulant laxatives
• Start with fiber supplementation
• Add an osmotic cathartic
• Then go to stimulants
Neurogenic Bladder (3)
– Distended bladder
– Overflow incontinence
- Flaccid
Neurogenic Bladder Tx (3)
– Parasympathomimetics – bethanechol – Catheter decompression
– Surgical severing of the internal vessicle sphincter
Impotence (5)
– Medical • Viagra, Cialis, Levitra • Intracorporeal injection of papaverine, phentolamine, alprostadil • Urethral pellets of alprostadil – Mechanical • External vacuum therapy – Surgical • Penile prosthesis
Guillian-Barre Syndrome (4)
- Acute or subacute progressive polyradiculoneuropathy
- Weakness is more severe than sensory loss
- Acute dysautonomia may be life-threatening
- Pathology shows primary demyelination or less commonly axonal degeneration
Guillian-Barre Presentation (4)
– Symmetric weakness starts proximally
– Starts in legs, then arms, then muscles of respiration or deglutition
– Sensory disturbances include paresthesias or dysesthesias, neuropathic or radicular pain
– Autonomic disturbances are common **
Guillian-Barre Differential Diagnosis (4)
- Rule out porphyric, diphtheric or toxic neuropathies with labs
- Acute timing excludes other peripheral neuropathies
- Exclude Polio, tick paralysis, botulism
- Focal cord lesion is suggested by asymmetric motor deficit, pyramidal signs, a sharp sensory level or early sphincter involvement
Guillian-Barre Tx (6)
– Steroids don’t help and might hurt – Plasmapheresis – IVIG – Supportive care • Ventilator support • Support of blood pressure
Guillian-Barre Prognosis
– 20% of patients have persisting disability
– The rest make a full recovery after several months
Myasthenia Gravis (5)
- Fluctuating weakness of commonly used voluntary muscles
- Activity increases weakness in affected muscles
- Onset is insidious**
- Autoantibodies bind to Ach receptors
- Powerful muscles fatigue rapidly
Myasthenia Gravis Presentation (7)
– Ptosis, diplopia, difficulty chewing or swallowing, respiratory problems, limb weakness
– May be focal or generalized
– Symptoms fluctuate during the day
– Exam confirms weakness and fatigability of affected muscles, improves with rest
– Sensation is normal and DTRs intact
– Myasthenic crisis: severe respiratory weakness
Myasthenia Gravis Diagnosis (2)
– Electrophysiologic tests shows decrementing response to repetitive 2-3Hz stimulation
– Serologic testing for acetylcholine receptor antibiodies is 80-90% sensitive
Myasthenia Gravis Tx (6)
– Avoid aminoglycosides
– Neostigmine/pyridostigmine (anticholinesterase) can be used but do not alter progression
– Thymectomy can help (patients <60, unless disease is focal)
– Corticosteroids are used if above measures fail – start in hospital
– Azathioprine
– Plasmapheresis or IVIG
Mononeuropathies (9)
- Carpal tunnel syndrome
- Pronator teres or anterior interosseus syndrome
- Ulnar nerve lesions
- Radial nerve lesions
- Femoral neuropathy
- Meralgia paresthetica
- Sciatic and common peroneal nerve palsies
- Tarsal tunnel syndrome
- Facial nerve palsy
Carpal Tunnel Syndrome
• Compression of the median nerve causing numbness, parasthesias and weakness in the hand • Caused by repetitive motion injury • Weakness of the hand** • Sensory disturbance of the thumb and digits
Carpal Tunnel Tx
– Wrist splint and rest
– Median nerve decompression
Pronator Teres or Anterior Interosseus Syndrome (3)
• Motor branch of the median nerve (anterior
interosseus) descends between the two heads of the pronator teres
• No sensory loss (as long as the median nerve itself is not affected)
• Caused by trauma or compression
Pronator Teres Syndrome Presentation (2)
- Weakness confined to the pronator quadratus, flexor pollicis longus and flexor digitorum profundus to the 2nd and 3rd digits
- May improve spontaneously, may need depcompressive surgery
Ulnar Nerve Lesions
Occur at the elbow, nerve runs posterior to the medial epicondyle and descends in the cubital tunnel
What are the causes of ulnar nerve lesions? (3)
– Impingement from trauma
– Change in carrying angle of the elbow
– Thickening of structures comprising the cubital tunnel
Ulnar Nerve Lesion Presentation (4)
• Weakness in the forearm and hand, sensory disturbance to medial 1 1⁄2 digits • EMG/NCS used to evaluate • Conservative measures • Surgical treatment – ulnar nerve transposition
Radial Nerve Lesions (3)
- Prone to injury/compression in the axilla
- Sensory deficit is small (back of hand between the thumb and index finger)
- Weakness of all muscles supplied by the nerve distal to the site of injury
Erb Palsy
- Brachial plexopathy
- Waiter’s tip
- From trauma, shoulder dystocia
Femoral Neuropathy (4)
- Weakness and wasting of the quadriceps muscle and sensory impairment over the anteriomedian aspect of the thigh
- Depressed or absent patellar reflex
- Caused by pressure from retroperitoneal neoplasms or hematoma. Poor positioning in lithotomy during surgery can also cause it.
- Also associated with diabetes
Meralgia Paresthetica (6)
- Irritation of the lateral femoral cutaneous nerve (usually unilateral)
- Obese, diabetic, pregnant
- Pain, parasthesia, numbness
- No other deficits
- Sometimes relieved by sitting
- Treatment – remove insult, hydrocortisone injection, surgical transposition
Sciatic Nerve Palsy (3)
- Most commonly caused by misplaced deep IM injection, trauma can also cause
- If part of the nerve is damaged, it is usually the peroneal part
- Distinguished on EMG from peroneal nerve palsy by involvement of the short head of the biceps femoris
Common Peroneal Nerve Palsy
- Caused by compression or injury near the head and neck of the fibula
- Weakness in dorsiflexion and eversion of the foot (foot drop)
- Numbness in the anteriolateral aspect of the calf and dorsum of the foot
Tarsal Tunnel Syndrome
- Posterior tibial nerve goes through the tarsal tunnel (posterioinferior to the medial malleolus) and supplies motor and sensory to the foot
- Compression leads to parasthesias, pain, and numbness over the bottom of the foot, especially at night (heel is spared)
- Muscle weakness is often subclinical
- Treatmentissurgicaldecompression
Facial Nerve Palsies
- Related to HIV infection, Lyme disease or sarcoidosis
- Otherwise, it is called Bell palsy (idiopathic)
- All cranial nerves except for VII (bilateral in upper distribution only) and XII receive bilateral innervation
Bell’s Palsy
- Sudden onset of lower motor neuron facial palsy
- Impaired taste or hyperacusis may occur • No other neurological abnormalities
- Attributed to an inflammatory reaction involving the facial nerve (stylomastoid foramen or in the bony facial canal)
- HSV may be implicated
- More common in pregnant women and diabetics
Bell’s Palsy Presentation
– Comes on abruptly, may worsen over first day or two
– Pain about the ear is common but this subsides in 2-3 days
– Face feels stiff and pulled to one side
– Restriction of eye closure
– Difficulty eating
– Fine facial movements are impaired
Bell’s Palsy Tx
– Corticosteroids may improve outcomes in patients with severe disease
– Must start within 5 days of onset
– Prednisone
– Protect the eye with lubricating drops and a patch if the eye cannot close
Lasting deficits of Bell’s Palsy occur when?
Most severe initial symptoms are present:
- Clinically complete Palsy on presentation
- Advanced age
- Hyperacusis
- Severe initial pain
- happens about 10% of the time
