POST POLIO SYNDROME

• Following the acute illness and a period of rehabilitation, polio patients eventually reached a plateau of neurological and functional recovery that was believed to remain essentially static

• However, research shows that over one half of the survivors of paralytic polio experience new health problems related to their original illness in about 30 to 50 years after their initial polio and include new weakness, fatigue, pain, and functional loss.

DEFINITION OF POST POLIO SYNDROME

• An otherwise unexplained constellation of symptoms which may include weakness, fatigue, pain, heat or cold intolerance, and swallowing, breathing, or sleep disturbance developing in a patient who had paralytic polio.

• Post Polio Muscle Atrophy (PPMA) has been used as the label for the above symptoms when they include progressive muscle atrophy

• The cardinal symptom is new weakness

A prior episode of paralytic polio confirmed by history, physical exam, and typical findings on EMG

• Documented history of polio (acute, febrile illness producing motor but no sensory loss)

• Noting whether other members of the patient’s family or neighbors had a similar illness

• Characteristic feature - focal, asymmetric weakness, and/or atrophy on examination

Standard EMG evaluation demonstrates changes consistent with prior AHCD• Increased amplitude and duration of motor unit action

potentials• Increased percentage of polyphasic potentials • In weak muscles, a decrease in the number of motor units

on maximum recruitment• Fibrillations and sharp waves may or may not be present

A period of neurologic recovery followed by an extended interval of neurological and functional stability preceding the onset of new problems

• Interval of neurologic and functional stability usually lasts 20 or more years

• Characteristic pattern of recovery - three stages(1)paralytic polio in childhood or later in life(2) partial to fairly complete neurologic and functional recovery(3) a period of functional and neurologic stability lasting many years(4) the onset of new health problems

Gradual or abrupt onset of new neurogenic, nondisuse weakness in previously affected and/or unaffected muscles

• May or may not be accompanied by other new health problems such as excessive fatigue, muscle pain, joint pain, decreased endurance, decreased function, and atrophy

• New neurogenic weakness is essential for making the diagnosis

Exclusion of medical, orthopedic, and neurologic conditions that might cause the health problems listed above

• Often the most difficult to establish• chronic illnesses, diseases, or psychiatric disturbances that

afflict the general population might affect polio patients as well

• Similar set of overlapping signs and symptoms may occur.• Eg. Compression neuropathies, radiculopathies,

degenerative arthritis, disc disease, obesity, anemia, diabetes, thyroid disease, and depression

Proposed Etiologies of Post-Polio Syndrome

Motor unit dysfunction due to overuse or premature aging of large motor units.

Musculoskeletal overuse

Musculoskeletal disuse

Chronic polio virus infection or virus reactivation

Motor neuron degeneration (glial, vascular, and lymphatic changes caused by acute polio)

Loss of motor units with normal aging

An immune mediated syndrome

Motor Unit Dysfunction Due to Overwork or Premature Aging of Polio Affected Motor Units

• Most widely accepted theory is that of neuron fatigue• The original viral attack of the anterior horn cells may have

left some motor neurons functional but impaired, making them more vulnerable to dysfunction as time passes

• Abiotrophy – loss of vitality

Muscle Overuse

• Both Windebank et al. at the Mayo Clinic and Maynard found that new weakness occurred more often in the weight-bearing muscles of the legs than in the non-weight-bearing muscles of the arms. And those limbs affected the most by the original disease were the most susceptible to new weakness.

• Chronic mechanical strains on joints, ligaments, and soft tissues that have not been supported well for 30 or more years

Muscle Disuse

• Well known that disuse leads to both deconditioning and muscle weakness in healthy individuals

• Similarly, polio individuals have been noted to have similar short-term increased weakness when forced to remain sedentary with illness or injury

Loss of Normal Motor Units with Aging

• While anatomical and electrophysiological studies have demonstrated that there is a loss of motor neurons with advancing age, this becomes prominent only after 60 years of age

• A recent study by Trojan et al. demonstrates that older individuals are more likely to develop PPS

Predisposition to Motor Neuron Degeneration Due to Glial, Vascular, and Lymphatic Damage• Some investigators have suggested - damage to the glial

cells and vascular supply at the time of infection can lead to secondary dysfunction of AHC

• While vascular damage is sometimes seen, it is believed that this is secondary to the severe inflammatory responses

• Most studies show that polio affects only the neural cells and not the glial or vascular endothelial cellstherefore it is unlikely that these changes play a large part in the clinical deterioration seen with PPS

Virus Reactivation or Persistent Infection

• Animal studies have shown that poliovirus and other picornaviruses may persist in the CNS and produce late or chronic disease

• an active controversy still exists regarding this hypothesis

An Immune-Mediated Syndrome

• A study by Pezeshkpour and Dalakas described what appeared to be evidence of an ongoing inflammatory or immune response -- active inflammatory gliosis, neuronal chromatolysis, and axonal spheroids in the spinal cords of polio patients who died many years later of other causes

• Steegman also found inflammatory infiltrates, including lymphocytes, plasma cells, and macrophages in the parenchyma and perivascular spaces in five of seven post-polio patients

• Antibodies are found that could be directed toward neurons, nerve terminals, or postsynaptic antigens. This suggests that PPS could be an autoimmune disorder mediated by antibodies produced in situ

Pathophysiology

Knowledge of the pathophysiology of acute polio is necessary to understand the possible causes for PPS

Poliovirus - positive single-stranded RNA enterovirus belonging to the Picornavirus group

Three polio viruses, 1, 2, and 3

4-8%Symptoms-

Low grade feverSore throatVomiting

Abdominal painLoss of apetite

MalaiseRecovery - Complete

1-2%Symptoms-

HeadacheNausea

VomitingPain, stiffness back and legs

Tripod signKiss the knee test

Head drop signNeck rigidity

Recovery – within 2-10 days

0.5-1%Phases-

Minor – same as abortiveMajor – msc pain, spasm, return of fever

Followed by – rapid onset flaccid paralysis complete within 72hrs

RareSymptoms-

IrritabilityDelirium

DisorientationTremors, convulsionsUMN type paralysis

InfectionInapparant 90-95%

Apparent 5-10%

Paralytic PMSpinal

Bulbar

BulboSpinal

Most common 80%Results from LMN lesion of AHC

Affects muscles of legs/arms/trunkSevere cases –

Quadriplegia/paralysis of trunk, abd, thoracic muscles

Assymetric paralysis (legs>arms)Descending paralysis

Floppy musclesReflexes diminishedSensation normal

Residual paralysis if after 60 days

2%Life threatening

Cranial nerve lesion – vagusSYMPTOMS-

Nasal twang, hoarsenessNasal regurg

DyspnoeaDysphagia

Child refuses feedChances of aspiration

Involvement of resp centre – Shallow irregular resp

Vasomotor centrePulse rapid weak thread

20%Combination

PATHOLOGY: PHYSIOLOGIC AND CLINICAL CONSEQUENCES

• EXTENSIVE NEURONAL INVOLVEMENT IN THE ACUTE POLIO INFECTION -In addition to the anterior horns in the spinal cord, infection involves intermediolateral horns and dorsal root ganglia. Infection also involves motor cortex, hypothalamus, and globus pallidus, brainstem nuclei, reticular formation, cerebellar roof nuclei, and vermis

• MOTOR UNIT REMODELING IN THE POST RECOVERY PHASE - Clinical improvement occurs acutely through recovery of mildly affected neurons, collateral sprouting, and strengthening (hypertrophy) of intact musculature.

PATHOLOGY: PHYSIOLOGIC AND CLINICAL CONSEQUENCES

Central fatigue may also be a factor.• Polio virus infection of

the motor strip and the reticular activating system

• A working definition for central fatigue is: "Increased mental effort necessary to perform a fixed amount of muscle contraction"

Increased metabolic burden on surviving anterior horn cells• fatigue • metabolic injury• collateral sprouts to some

muscle fibers will degenerate• The strength of these muscle

fibers will be lost to the motor unit

Another mode of decompensation is muscle fiber based• Rapidly firing muscle fibers• more lactic acid • may not be adequately

dissipated. • Muscle fiber fatigue • muscle fiber injury, lost

function, and a spiral of decline

DECOMPENSATION THEN PRODUCES POST POLIO SYNDROME

Diagram showing the neuromuscular effects of polio and the PPS

Normal motor units showing healthy motorneurons, their axons and the muscle fibres they innervate

Initial polio virus with varying motorneuron death and denervation of their muscle fibres (dotted line)

Recovery-Axons from surviving motor neurons sprout new fibres to innervate denervated muscle fibres

Early PPSNew loss of nerve fibres and muscle fibre denervation

Late PPS with further loss of nerve fibres and muscle fibre denervation

Residual paralysis

• Acute phase of illness lasts 0-4 weeks• Recovery variable• At 60 days – mild to severe residual paresis• Max recovery – first 6 months• Slow recovery – upto 2 yrs• After 2 yrs – Post Polio Residual Paralysis persists

PRIME SYMPTOMS

• Statistical summary of the clinical characteristics of several series of PPS patients is as follows:

1. Fatigue, Pain, and Weakness are almost always present. Fatigue (89%); Pain in Muscle or Joint (86%); New weakness (83%) in previously symptomatic (69%) or asymptomatic (50%) muscles.2. New Atrophy (28%); This equates to Post Polio Muscular Atrophy (PPMA)3. Activities of daily living difficulties (78%) = functional loss

Walking (64%)Climbing Stairs (61%)Dressing (17%)

ADDITIONAL PRESENTING PROBLEMS1.Pulmonary dysfunction from weakness of the

respiratory muscle2.Dysphagia - Many PPS patients reported some new

difficulty with eating or swallowing more commonly in those with bulbar polio. Some progressive speech difficulty such as increased hoarseness, weakness, or slurring.

3.Cold intolerance (29%) - Limbs may be cold and cold exposure produces weakness. This is thought to be due to intermediolateral column involvement resulting is vasoparesis, venous pooling, and excessive heat loss

4.Degenerative arthritis - A joint that is biomechanically disadvantaged may develop degenerative arthritis.

5.Social and psychological problems

PAST HISTORY

• Average age of polio onset is 7 years. • Median period of stable neurologic and functional status is

25 years.• Median post polio symptom duration before patient

presents for evaluation is 5 years.• Variables associated with shorter interval to PPS: greater

severity and greater age.• Initial symptoms are most frequent in the lower limb most

affected in the acute illness. (Upper extremity weakness is easier to compensate for without overuse resulting.)

• The onset is usually insidious

ELECTRODIAGNOSTIC FEATURES

EMG in acute poliomyelitis is –• Poor MUAP recruitment at the onset of weakness• Followed by the development of fibrillation potentials in widespread muscle groups after 3 to 4

weeks• Fibrillation potentials subside as reinnervation by surviving motor units proceeds during recovery.

The same is true in chronic polio. • Some investigators report that there is an increase in muscle membrane instability between those

patients that are clinically stable (no new weakness) and those who are clinically unstable (new weakness).

• The muscles that become extremely weak and atrophic have few to no MUAPs, but virtually all, including clinically normal muscles, will have large, polyphasic MUAPs and abnormal, decreased recruitment

Causes of Pain in the Polio Survivor

Post-Polio Muscle Pain

Pain in polio-affected muscles- • May be similar to pain of acute polio -

very much like the pain pt. had with acute polio, if they remember that

• Associated with muscle cramps, twitching, or crawling sensation

• Often increased at night or end of day and at rest

• Exacerbated by physical activity, stress, and cold

Overuse syndromes and soft tissue pain

• Caused by injury or inflammation of soft tissues: muscles, tendons, bursa, and ligaments

• Strains, sprains, tendonitis, bursitis, myofascial pain

• Overuse syndromes from the repetitive use of mobility aids

• Often affects strong limb- Related to body mechanics, positioning, posture

Biomechanical/degenerative disease pain• Changes in normal joints due to wear and

tear• Excess stress of joints due to altered body

mechanics• Joint deformity• Degeneration in spine-discs, joints and

increased curvature• Secondary nerve compressions

• If there are sensory changes, there’s something going on in addition to post-polio changes

Bone pain

• Osteoporosis• Fractures:

• Traumatic severe fracture, compound fractures and multiple breaks

• Spontaneous

Comprehensive mx of

PPS

NEUROLOGY

PHYSIATRY

PHYSICAL

THERAPY

SUPPORT

GROUPSPULMONOLOGY

PSYCHOLOGY

OT

SPEECH PATHOLOG

Y

Occupational Therapy and Post Polio Syndrome

• Energy conservation and work simplification• Upper limb splints and orthoses eg. mobile arm support • Assistive technology and adaptive equipment

● toilet aids, bath/shower aids, ● handrails, ● long handled reachers, ● long handled personal care cleaning devices, and● plate guards

• Mobility eg. assessment of mobility devices that do not include walking aids. consists of assessment regarding the need for wheelchairs

• Environmental modifications to home area• Vocational rehabilitation

Physiotherapy- Cornerstone of PPS mx

Management of New WeaknessControversialEarly case reports (1915-1957) - exercise resulted in further damage to already vulnerable motor units and resulted in increasing weaknessOther studies (1948-1966) - progressive resistive exercises produced improvements in muscle strengthGuidelines - Appropriate individualised exercise programmesMonitore for deterioration in muscle strength, increased pain or increased fatigueLearn to monitor and manage weakness and fatigue prior to commencing an exercise programmeAvoid muscle overuse, manifested as an aching on exertion

Physiotherapy- Cornerstone of PPS mx

Management of pain• Decrease Muscle Load To Less Than Muscle Capacity:

• PACING - break up activities into smaller modules of time, each of which is of less duration than the time required to produce fatigue

• A corollary concept - ENERGY BUDGETING which imagines that one has a fixed expenditure of energy for each day and that this sum should be "spent" on activities of the highest personal priority

• Weight reduction• Use of aids and appliances to relieve or support weak muscles and joints• Electrophysical agents - Heat / TENS • Stretching exercises / Strengthening exercises • Hydrotherapy

The role of the Orthotist

Role is that of biomechanical back up to the clinical team. Provides- • Insoles • Foot orthoses• Ankle-foot orthoses (AFO)• Knee ankle foot orthoses (KAFO) • Spinal jackets

Pharmacological interventions

• Amantadine, bromocriptine and modafinil act on different regions of the brain and are intended to address generalised fatigue in PPS

• Insulin-like growth factor (IGF-I) and human growth hormone, which stimulates the secretion of IGF-I (IGF-I is thought to enhance regeneration of peripheral nerves by axonal sprouting which in turn positively influences muscle strength)

• Medications for the amelioration of fatigue must be understood as aids which can give a running start to the rehabilitation process. However, if they are perceived by the patient as a form of curative treatment, they will only forestall the day of reckoning.

Thank you