ACUTE FLACCID PARALYSIS (AFP) SAMAH K. ABURAHMA, MD THIS LECTURE INCLUDES AUDIO RECORDING ACUTE FLACCID PARALYSIS (AFP) • The sudden onset of generalized flaccid weakness in the absence of symptoms of encephalopathy or other brain demages… implicates the motor unit (so LOWER) • AFP is an emergency, management priorities are to support vital functions and reach a specific diagnosis in a timely manner with a focused history and physical examination THE INITIAL COMPLAINT • Weakness is almost always first noted in the lower extremities • Many disorders involve the legs first • Symptoms of leg weakness are more obvious than arm weakness • Abnormal gait is the initial complaint with proximal or distal leg weakness THE INITIAL COMPLAINT • With proximal weakness • The pelvis is not stabilized and waddles from side to side (waddling gate) • Difficulty ascending stairs with hip extensor weakness • Difficulty descending stairs with quadriceps weakness • Difficulty arising from chair THE INITIAL COMPLAINT • With distal weakness • Stumbling (stolpern) is an early complaint • Falling on uneven surfaces at first, then “tripping on nothing at all” • Repeated ankle spraining (verstaucht) because of lateral instability • Children with foot drop will lift the knee high in the air so the foot will clear the ground THE INITIAL COMPLAINT • Older children will complain of specific disabilities • Limb weakness often associated with weakness of muscles of the head and neck • Inquire about diplopia, drooping eyelids, difficulty chewing and swallowing, facial expressions, and voice changes CLINICAL EXAM • Look for atrophy or hypertrophy • Fasciculations • Palpate muscles for tenderness and texture • Joint contractures, myotonia • Strength and tendon reflexes CLINICAL EXAM • Watch the child sit, stand, and walk • Difficulty with transitional movements (proximal weakness) • Unable to sit up from lying down • Unable to stand up from the floor without assistance (Gower sign), unable to stand up from a chair • Waddling gait • Distal weakness • Unable to toe walk, heel walk CLINICAL EXAM • Neck flexion/extension • Particular attention to oculomotor exam, speech (nasal speech), cough • Assess the presence of facial weakness • Sensory exam • Vibration/proprioception • Sensory level ACUTE FLACCID PARALYSIS • Guillain Barre Syndrome • Transverse Myelitis • Poliomyelitis • Botulism GUILLAIN-BARRE SYNDROME (GBS) • The commonest cause of acute flaccid paralysis (AFP) in previously healthy children • Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) • Acquired, monophasic • Symmetrical progressive ascending weakness, areflexia, variable sensory complaints, and elevated CSF protein without pleocytosis (so normal cell counts) PATHOPHYSIOLOGY OF GBS • Immune mediated disease – molecular mimicry • Two thirds of cases follow a respiratory or gastrointestinal infection • Campylobacter Jejuni infection is the most common, but other organisms include CMV, EBV, HSV, enteroviruses, … PATHOPHYSIOLOGY OF GBS, CONT. • The main lesions are acute inflammatory demyelinating polyneuropathy (AIDP), the most common form • Acute motor axonal neuropathy (AMAN), particularly after C. jejuni infection • A variety of autoantibodies to gangliosides have been identified especially with axonal forms of the disease GBS - CLINICAL FEATURES • Two to four weeks after a benign febrile illness • Common presentations are paresthesias in the fingers and toes, pain is a common presentation in children (79%), particularly low back pain (could mask the presence of weakness and delay the diagnosis) • Symmetrical weakness in the lower extremities, that ascends over hours to days to involve the arms, and in severe cases respiratory muscles GBS - CLINICAL FEATURES • Cranial nerves are affected in 30% • Facial nerve with bilateral facial weakness • Oculomotor palsies • More than 90% of patients reach the nadir of their function within 2-4 weeks GBS - PHYSICAL EXAMINATION •Symmetrical weakness with diminished or absent reflexes •Vibration and position sensation are affected in 40% of cases •50% of patients have evidence of autonomic dysfunction • Cardiac dysrythmias • Orthostatic hypotension, hypertension • Paralytic ileus • Bladder dysfunction GBS - DIAGNOSIS • Dx is usually clinical with ruling out important differential diagnoses such as spinal disease • No single diagnostic test is reliable in making the diagnosis early in the course of the disease • CSF hyperproteinemia may not be evident till 10 days after onset • Earliest: MRI of the lumbar spine: nerve root enhancement can be seen in up to 90% of cases, as early as 2 days after onset of disease • Nerve conduction studies: earliest manifestation of prolonged F wave minimal latencies not evident till 7 days after onset • Antiganglioside antibodies: antiGQ1b in Fisher syndrome DOUBT THE DIAGNOSIS OF GBS IF • Marked persistent asymmetry of weakness (consider infection like polio or spinal cord disease) • Persistent bladder or bowel dysfunction (consider spinal cord disease) • Bladder or bowel dysfunction at the onset • Sharp sensory level (consider spinal cord disease) • Mononuclear leukocytosis in CSF > 50 (consider infection like polio) • Pupillary abnormalities are not seen in GBS (consider botulism; HOWEVER, oculomotor N dysfunction is common!!) GBS MANAGEMENT • Immune modulatory therapy for rapidly progressive cases, most effective the first 10 days • Plasma exchange • IVIG • Steroids are not effective and not indicated • Critical care monitoring • MCC of death is autonomic dysfunction • Second most common cause of death is respirotory failure GBS – NEUROMUSCULAR RESPIRATORY FAILURE •Close monitoring of motor, autonomic, and respiratory function •Predicting impending respiratory failure: • Clinically: paradoxical breathing (the chest and abdomen move in instead of out while taking a breath, a classical sign of impending neuromuscular respiratory failure), unable to count to 20 in single breath, SOB, tachycardia, fatigue •Clinical predictors of mechanical ventilation in GBS: • Bulbar weakness (inability to protect airway soon) • Neck flexor weakness (same myotome as diaphragm-C2&C3) • Rapid progression • Autonomic dysfunction •Delayed intubation leads to aspiration and increases pulmonary morbidity PROGNOSIS OF GBS IN CHILDREN • Generally good • Children have a shorter clinical course than adults • Severity of the illness does not correlate with long term outcome, 85% of children have excellent recovery • 50% are ambulatory by 6 months, 70% walk within a year of onset of the disease ACUTE FLACCID PARALYSIS • Guillain Barre Syndrome • Transverse Myelitis • Poliomyelitis • Botulism TRANSVERSE MYELITIS • A subtype of myelitis (inflammation of the spinal cord) characterized by rapid paralysis and sensory changes below the level of the affected segment. Sometimes associated with a band-like sensation across the trunk. Causes include infections (e.g., herpes zoster), autoimmune disorders, and vascular malformations • The most important DDx of GBS in the acute setting is spinal cord disease, especially transverse myelitis • Immune mediated spinal cord inflammation • Myelitis maybe complete, or incomplete, leading to a heterogeneous clinical presentation • Varying degrees of severity • Clinical picture related to functional interruption of descending and ascending fibers TRANSVERSE MYELITIS – SPINAL CORD ANATOMY TRANSVERSE MYELITIS • Presentation of immune myelitis overlaps with symptoms of myelopathy due to any underlying cause, e.g. vascular, neoplastic…..patients with myelopathy are a TRUE MEDICAL EMERGENCY, URGENT MRI of the spine is indicated in any patient with evidence of spinal cord dysfunction because emergent surgery might be needed TRANSVERSE MYELITIS • Commonly presents with an ascending weakness (asymmetrical presentation possible) • Initially reflexes may be depressed or absent because of spinal shock or involvement of the nerve roots • Must be considered in cases of limb weakness without bulbar involvement TRANSVERSE MYELITIS • Mean age of onset is 9 years • Symptoms progress rapidly, peaking within 2 days • Usually level of myelitis is thoracic • Sensory level, asymmetrical leg weakness, and early bladder involvement. Back pain is common at the onset • Tendon reflexes may be decreased or increased • Recovery usually begins after a week of onset TRANSVERSE MYELITIS • Diagnosis: MRI of the spine usually shows swelling of the cord, but at times is normal. Exclusion of acute cord compression is CRITICAL though • Treatment: high doses of IV steroids followed by tapering doses of prednisone • Prognosis: 50% make a full recovery, 40% recover incompletely, and 10% do not recover ACUTE FLACCID PARALYSIS • Guillain Barre Syndrome • Transverse Myelitis • Poliomyelitis • Botulism ENTEROVIRUS INFECTION • Poliovirus: a group of RNA viruses (coxsackievirus A&B, Rhinovirus and Poliovirus) that inhabit the GI tract of humans, transmit by fecal-oral route and cause different infections • They are neurotropic, and produce paralytic disease by destroying the motor neurons of the brainstem and spinal cord with muscle atrophy in the involved myotomes • Poliovirus causes the most severe paralysis POLIOMYELITIS • Epidemics usually occur in the spring and summer • Usually, poliomyelitis infection is asymptomatic. However, in few patients, CNS infection (manifested by toxic appearance, meningism, headache and vomiting) followed by typically asymmetrical weakness which might effect the respiratory muscles in severe cases • Usually, a brief illness characterized by fever, malaise and GI symptoms precedes the paralytic illness • After the febrile illness, there is a brief period of apparent well being, after which the fever recurs, with headache, vomiting and meningeal irritation POLIOMYELITIS • Pain in the limbs and spine is followed rapidly by limb weakness • Pattern of limb weakness is variable, but is generally asymmetric • Weakness, diminished reflexes and muscle atrophy are seen • Paralysis POLIOMYELITIS • Bulbar polio may occur with or without spinal polio and is life threatening • Affected children have prolonged periods of apnea and require mechanical ventilation • Extraoccular muscles are spared • Paralytic polio is rarely seen after the introduction of the polio vaccine POLIOMYELITIS • Diagnosis: • Clinical suspicion • CSF leukocytosis is seen the acute phase, elevated protein may also be seen • CBC shows leukocytosis • Virus recovery from stool is essential • Obtain stool, blood and throat samples for viral serology, demonstrating a four fold rise in IgG is helpful but not always easy. Positive IgM antibodies is diagnostic POLIOMYELITIS • Treatment: mainly supportive • Mechanical ventilation may be needed in bulbar involvement • Pain management for paresthesia • Physical therapy Most patients do not regain their full strength ACUTE FLACCID PARALYSIS • Guillain Barre Syndrome • Transverse Myelitis • Poliomyelitis • Botulism BOTULISM • Food born botulism: ingestion of preformed botulinum toxin • Infant botulism: ingestion of clostridial spores that inhabit the GI and release toxin in vivo • Wound botulism: infection of a wound with in vivo toxin production • Adult enteric infectious botulism: ingestion of clostridial spores BOTULISM • Spores of C. botulinum are heat-resistant • spores can be destroyed by heating to 120ºC for five minutes • Factors favouring toxin production • Restricted oxygen exposure (either an anaerobic or semianaerobic environment) • Low acidity (pH >4.6) water • A temperature of 25 to 37ºC for ideal growth • Preformed food that stays in airtight temperature for a long time provides ideal growth circumstances (like honey), fermentation too, refrigeration and cooking are protective BOTULISM - PATHOGENESIS • Botulinum toxin inhibits acetylcholine release at presynaptic nerve terminals • Decreased neural transmission in both autonomic and motor peripheral nerves • Return of synaptic function requires sprouting of a new presynaptic terminal…about 6 months BOTULISM – CLINICAL FEATURES • Acute onset of bilateral cranial neuropathies associated with symmetric descending weakness • Absence of fever • Symmetric neurologic deficits • The patient remains responsive • Normal or slow heart rate, normal blood pressure • No sensory deficits with the exception of blurred vision BOTULISM – CLINICAL FEATURES •Food-borne botulism: within 12 to 36 hours after ingestion •Prodromal symptoms: nausea, vomiting, abdominal pain, diarrhea, and dry mouth •Respiratory difficulties requiring intubation and mechanical ventilation are common •classic pentad: dry mouth, nausea/vomiting, dysphagia, diplopia, and fixed dilated pupils. BOTULISM – CLINICAL FEATURES • Wound botulism: • Lacks the prodromal GI symptoms common to food-borne botulism and has a longer incubation period of approximately ten days • Fever may be present • Infant botulism: • Differential diagnosis of the hypotonic infant • Constipation, weak cry and suck, dilated pupils, decreased gag reflex, ptosis, and intact deep tendon reflexes BOTULISM: DIAGNOSIS • Clinical suspicion • Detection of botulinum toxin in the serum, stool, or suspected food source • Nerve conduction studies • Typical findings on repetitive nerve stimulation BOTULISM: TREATMENT • Monitoring: pulse oximetry, spirometry, arterial blood gas measurement, and clinical evaluation of ventilation, perfusion, and upper airway integrity • Intubation and mechanical ventilation in severe cases • Respiratory failure is the primary cause of death • Nutritional support BOTULISM: TREATMENT • Antitoxin should be administered as early as possible.Equine serum botulism antitoxin • Human-derived botulinum immune globulin (BIGIV) for infant botulism • Equine derived antitoxin for all other forms • Wound debridement, antibiotics • Aminoglycosides are contraindicated RAPIDLY PROGRESSIVE WEAKNESS • Emergency evaluation: • ABCs • Support and stabilize patient • Focused history • Attempt to localize weakness • Labs, studies • Triage…. NEUROMUSCULAR RESPIRATORY FAILURE •Neuromuscular respiratory failure sequence of events (in contrast to resp failure due to lung pathology) • Atelectasis with mild hypoxia • Progressive diaphragmatic and intercostal muscle weakness leading to hypercapnic respiratory failure • Rapid respiratory deterioration: Hypoxia is a late manifestation that can occur precipitously •Spirometry every 4 hours: vital capacity, maximum inspiratory pressure, maximum expiratory pressure NEUROMUSCULAR RESPIRATORY FAILURE • Children less than 6 years • Sustained increase of pCO2 to >=50 mmHg • Increasing respiratory rate • Increasing oxygen requirement • Increased use of accessory muscles • Sweating, wide pulse pressure • Normal Vital capacity: 70nl/kg COMMUNICATION ISSUES • Patients with acute weakness are usually mentally intact, but unable to move • Weak patients may not be able to communicate verbally • Explain everything to patient • Loss of control and helplessness provoke severe anxiety • Attempt nonverbal communication: blinking, finger movements, … • Pay attention to expressions of pain and patient’s posture and comfort AFP-PEARLS • Acute and subacute weakness, or rapidly progressive weakness is a medical emergency • Management priorities are to support vital functions • Detailed history and examination are indispensable for reaching a diagnosis and tailoring investigations
