PNS Part III

Question 1

Describe Guilian Barre Syndrome

Answer 1

• Overall rare, but most common rapidly evolving inflammatory PND characterized by rapid-onset motor paresis and sensory deficits (since after the eradication of polio)
• Autoimmune inflammatory disorder where body’s immune system mistakenly attacks the PNS
• Often, the immune destruction is triggered/preceded by respiratory/GI infections
• Initially, it was described as a single disorder characterized by PNS demyelination, but now considered as having several variants, where axons may also be attacked, depending on the type of infection

Question 2

Incidence, etiology, and risk factors of Guilian Barre

Answer 2

• 1-2 cases per 100,000
• Can occur at all ages, but peaks during young adulthood and in 5th-8th decades
• Men slightly more affected than women, whites more than blacks
• 90% of GBS had prior illnesses (GI or respiratory infections) during preceding 30 days
• Bacterial and viral infections are associated with it, Campylobacter jejuni (associated with axonal form), cytomegalovirus (associated with greater sensory involvement), haemophilus influenza, etc.
• Sometimes reported to occur following surgery or vaccinations…also reported following COVID 19 (but rare)

Question 3

Pathogenesis of Guilian Barre syndrome

Answer 3

• Antibodies are produced after possible infections, which mistakenly label antigens on surface of myelin sheath, as per molecular mimicry autoimmune theory
• Immune cells (T-cells, macrophages) attack myelin sheaths and start to strip myelin at the Nodes of Ranvier
• Schwan cells remyelinate axons, forming shorter internodes
• Inflammation causes a longer-term effect - products released by T-cells and macrophages also destroy neighboring axons: ‘bystander effect’
• If axonal damage, recovery of Wallerian degeneration would take longer time
• Auto-immune destruction of myelin sheath and axons can occur throughout the PNS from spinal roots to nerve terminals

Question 4

Clinical manifestations of Guilian Barre syndrome

Answer 4

• Classic presentation is of rapid onset of weakness, beginning distally in legs or arms, progressing to trunk, reaching peak weakness in 2-3 weeks. Sometimes facial, palatal and muscles of mastication may be get affected.
• Initial symptoms: tingling/paresthesia often in toes, followed within hours-to-days by distal weakness
• Rapidly ascending symmetric motor weakness
• Generally, progression of symptoms stop by 4 weeks, then a static phase lasts for 2-4 weeks, then recovery begins in proximal to distal direction. Recovery may take months to years.
• Flaccid paralysis accompanies loss of DTRs
  ANS might be involved, abnormalities in cardiac rhythm, BP changes
• Severe cases: respiratory muscles can be involved, may need artificial ventilation

Question 5

Slide 6

Question 6

How to diagnose Guilian Barre syndrome

Answer 6

• Medical history
• Disease progression
• Clinical exam
• NVC/EMG
• Lab tests like lumbar puncture for CSF proteins

Question 7

Treatment for Guilian Barre syndrome

Answer 7

• Plasmapheresis or plasma exchange: filtering circulating antibodies out of plasma or removing plasma & substituting with a fluid; typically 4-6 exchanges of 500ml per treatment over a period of a week
• High dose IV IGs: 0.4 g/kg/day for 5 days
• Outcomes for both approaches are equivalent

Question 8

Prognosis fo Guilian Barre syndrome

Answer 8

• Most people recover completely
• 20% can have residual neurologic deficits
• Complications that can persist: neuropathic pain, autonomic changes, distal weakness
• Factors that predict poor outcomes: onset at older age, protracted time before recovery begins, need for artificial respiration
• 5% mortality rate

Question 9

Guilian Barre syndrome implications for PT during progressive phase

Answer 9

• Focus is to prevent complications associated with immobility (mostly in ICU setting)
• Maintain ROM, prevent contractures
• Meticulous skin care to prevent skin breakdown, strict turning schedule
• Hot packs and gentle massage for musculoskeletal pain
• Monitor ABGs, SpO2, for respiratory function
• Encourage deep breathing and coughing to maintain clear airway and prevent atelectasis
• Precautions to prevent respiratory infections

Question 10

Guilian Barre syndrome implications for PT when disease stabilizes & recovery begins

Answer 10

• Gentle stretching
• Avoid over stretching and over use of painful muscles, can prolong recovery
• Active-assisted exercises -> progressing to active exercises - PNFs are good options
• If tolerated, higher intensity exercises are more beneficial than lower intensity exercises
• Continued impairment may require ADs, w/c

Question 11

Describe Postpolio syndrome/Postpolio muscular atrophy

Answer 11

• Polio infection was virtually irradiated in the 1950-60s by polio vaccine (Salk/Sabin vaccines)
• Survivors of polio attack are older adults now
• PPS refers to new neuromuscular symptoms that occur to polio survivors decades after recovery from the acute paralytic episode of poliomyelitis infection
• PPS is known to affect 20-50% of polio survivors

Question 12

Pathogenesis of Polio

Answer 12

• Polio virus gets transmitted by ingesting contaminated food or water
• Polio infection followed one of the 3 patterns: Asymptomatic (~70%); Non-paralytic, that produced GI or flu-like symptoms and muscular pain (~25%), recover in 1-2 weeks; Paralytic, began with flu-like symptoms, with asymmetric paralysis within a week, due to virus killing anterior horn cells

Question 13

Clinical presentation following initial Polio attack

Answer 13

• Unique peripheral neuropathy presentation: focal asymmetric motor involvement without any sensory deficits
• Extent and degree of paralysis depended on AHC involvement, wallerian degeneration of axons and muscle atrophy. Many suffered temporary paralysis, others permanent.
• Of the people with acute spinal polio attack, many recovered (50%), some had mild residual paralysis (25%), others had moderate to severe paralysis (25%)
• Recovery occurred due to various reasons: survival of AHCs, collateral sprouting from intact peripheral nerves connecting to denervated muscles (next slide) and hypertrophy of spared muscles

Question 14

Etiology of post polio syndrome

Answer 14

• Polio was thought to be a self limiting disease with no progression after initial paralytic episode
• Later studies confirm that denervation occurs again decades later in both clinically affected & unaffected muscles
• Progression is more rapid than that occurring in normal aging, rate of motor unit loss is twice of that occurring in healthy older people

Question 15

Pathogenesis of post polio syndrome (PPS)

Answer 15

• PPS is manifested when the nervous system cannot maintain the compensatory re-innervation of the muscles by collateral sprouts, that resulted in recovery/stabilization of the disease after the initial attack
• The nervous system starts pruning back axonal sprouts of the enlarged motor units that it cannot metabolically support any longer, thus new denervation occurs

Question 16

Clinical manifestations of post polio syndrome

Answer 16

• New weakness, muscle atrophy, pain and fatigue in the limbs that were originally affected, or in limbs that were not affected previously
• Very slowly progressing condition marked by periods of stability followed by new declines in the ability to carry out ADLs, but deterioration of strength occurs faster than normal aging
• Excessive fatigue even with minimal activity
• Pain: commonly in low back, UE joints, worse at night or with increased activity, and with climate changes
• Problems breathing or swallowing, sleep-related breathing disorders

Question 17

How to diagnose post polio syndrome

Answer 17

• Can be difficult as symptoms can be non-specific
• Requires exclusion of other neurologic or orthopedic disorders that could explain new symptoms
• EMG
• Muscle biopsies
• Prognosis: slowly progressive condition

Question 18

Treatment for post polio syndrome

Answer 18

• Symptomatic treatment, consisting of rest, analgesics
• Modification of lifestyles using education about energy conservation strategies, home modifications
• ADs and surgery for residual deformities (e.g., arthrodesis, tendon transfers)

Question 19

Post polio syndrome implications for PT

Answer 19

• Use of submaximal intensity exercises are recommended to maintain/improve endurance and functional capacity
• Fatigue should be avoided, vitals to be monitored before, during and after exercises, energy conservation techniques
• Contraindications to exercise would be increased pain and weakness
• Reassessment/modification of orthoses for gait, as previous orthoses may not be sufficient anymore
• Per research, individuals with PPS who engage in physical activity twice weekly demonstrate better gait than those who are less active.

Question 20

Describe Myasthenia Gravis

Answer 20

• Most common disorder of the NMJ (others are LEMS, botulism)
• Chronic autoimmune disorder
• Characterized by fluctuating weakness and fatigability of skeletal muscles
• Incidence: 1 in 200,000
• Can affect people in any age group, but peak in women in 20s-30s and in men in 50s-60s
• Women more than men

Question 21

Risk factors for Myasthenia Gravis

Answer 21

• Associated with thymic disorders like hyperthyroidism, thymic tumor, thyrotoxicosis
• Thymus produces/matures T-lymphocytes, trains them to recognize foreign and self antigens
• Also associated with RA, lupus, diabetes
• Hormonal associations: exacerbations can occur before menstrual cycle or shortly after pregnancy
• Any chronic infections can exacerbate MG

Question 22

Describe the neuromuscular junction

Answer 22

• Motor end plate: site where axon & muscle fiber meet; sarcolemma folded; nuclei & mitochondria are abundant
• Muscle contractions are triggered when nerve impulses are conducted by neurotransmitter Ach at the synaptic junction. Post synaptic receptors are called nicotinic Ach receptors

Question 23

Pathogenesis of Myasthenia Gravis

Answer 23

• In MG, nicotinic acetylcholine receptors at the junction between the nerve and muscle are blocked/destroyed by antibodies, which prevents nerve impulses from being transmitted
• Also, motor end plates are flattened, resulting in less receptors

Question 24

Clinical manifestations of Myasthenia Gravis

Answer 24

• Cardinal features are fluctuating muscle weakness and fatigability
• Repetition of activity causes fatigue, rest restores normal activity
• Muscles affected in MG: Ocular >50% of cases (ptosis & diplopia usually the first signs), Muscles of face & throat, Sometimes weakness of respiratory muscles (could be triggered by stress, infection, fever, etc), Neck & limb muscles affected (UEs more often affected the LEs), waddling gait
• Typically MG starts with ocular muscles, then evolves into generalized type involving extremity and other muscles

Question 25

How to diagnose Myasthenia Gravis

Answer 25

• Using physical exam to observe fatigue with continued use, and improvements with rest
• Blood tests for presence of anti-Ach receptor antibodies
• EMG: normal EMG at rest, rapid decrement in action potential amplitude with repeated activity
• Absence of sensory deficits and normal DTRs also help to confirm MG
• Tests for ocular MG: Simpson’s test, Ice test, rest test

Question 26

Treatment for Myasthenia Gravis

Answer 26

• Using medications known as acetylcholinesterase inhibitors such as neostigmine and pyridostigmine
• Corticosteroid immunosuppressants such as prednisone or azathioprine
• Surgical removal of the thymus gland
• Plasmapheresis and high dose intravenous immunoglobulin

Question 27

Prognosis of Myasthenia Gravis

Answer 27

• Course of MG is variable, with remission and exacerbations
• Overall slowly progressive, reaching worst condition within a few years from onset
• Symptoms fluctuate in intensity during the day
• Daily fluctuations are superimposed on longer term relapses
• Myasthenia crisis is medical emergency: failure of respiratory and/or oropharyngeal muscles causing airway obstruction or aspiration , requires ventilator assistance, sometimes it is the first manifestation of MG

Question 28

Myasthenia Gravis implications for PT

Answer 28

• In ICU setting: if respiratory muscles are affected, encourage deep breathing exercises and coughing
• During eating, person should sit upright and swallow with chin tipped downward towards chest, and never extended, to prevent aspiration
• Never speak with food in mouth
• Avoid strenuous exercise programs, stress, allow frequent rest periods to minimize fatigue
• Per research, for mild-moderate MG cases, strength training program using maximal isometric contractions can be beneficial
• Outcome measures: MG_DIS (self reported outcome measure), QMG (quantitative measure for MG severity)

Question 29

Describe complex regional pain syndrome (CRPS)

Answer 29

• A group of chronic pain syndromes that often worsens with time, generally characterized by severe pain out of proportion to the original injury
• Characterized by sensory, motor changes and sympathetic dysfunction w/ or w/o known trauma

Question 30

What are the types of CRPS

Answer 30

• CRPS I (formerly RSD) – caused by injury that did not directly damage the nerves in the affected limb, most (90%) CRPS is of this type.
• CRPS II (formerly causalgia) – associated with known nerve trauma
• CRPS-NOS (not otherwise specified) – partially meets CRPS criteria

Question 31

Etiology and pathogenesis of CRPS

Answer 31

• No known cause, not understood well
• Associated with a variety of conditions –PNI, fractures, amputation, surgical procedures, TBI, CVA, MI, bites, infections, falls, shoulder subluxation/dislocation, any event that causes traction in brachial plexus, or just sprained ankle.
• Exaggerated pain is associated with sympathetic overactivity
• Normally sympathetic activity after trauma causes vasoconstriction. This process shuts down automatically in minutes
• In CRPS, there is abnormal facilitation of sympathetic nervous system, causing cycle of pain and swelling, initially increasing skin temperature and later causing cyanosis and cold temperature.

Question 32

Clinical manifestations of CRPS

Answer 32

• Abnormally exaggerated pain processing (hyperalgesia, allodynia) – may spread proximally, and also from ipsi to contra side
• Edema
• Vasomotor changes - skin color and temperature changes (initially red/warm, later cold/cyanotic skin)
• Trophic changes (changes in sweating, changes in hair growth, brittle nails, thin glossy skin)
• Motor dysfunctions (weakness, atrophy, joint stiffness, tremors, spasms)
• Bone changes

Question 33

What are the 3 progressive clinical stages of CRPS

Answer 33

• Acute inflammation: pain, swelling, redness, sensitivity to touch
• Dystrophic: alternating between sweaty and cold, skin color changes from red-to-white-to-blue
• Atrophic: severe muscle and bone changes, atrophy, osteoporosis, contractures

Question 34

How to diagnose and treat CRPS

Answer 34

• No “gold standard”
• Diagnosis using hx and clinical exam
• Budapest criteria for diagnosis
• Diagnosis may be delayed due to its evolutionary nature
• Bone scans, sympathetic nerve blocks helps diagnosis
• Needs prolonged multidisciplinary treatment using meds (steroids, NSAIDS, spinal cord stimulators, intrathecal pumps) and physical therapy

Question 35

CRPS implications for PT

Answer 35

• Goals of rehab to reduce pain and encourage use of involved extremity
• Desensitization techniques – progressive stimulation with very soft materials to more textured fabrics, from light touch to deep pressure, from consistent to intermittent touch
• Modalities like TENS during the earlier stages of CRPS
• Graded exposure techniques - motor imagery -> mirror therapy -> movements
• Stress loading activities (loading and scrubbing) followed by distraction force (carrying weights)