CHAPTER A Case Based Approach to Acute Flaccid

89 Salil Gupta

CASE VIGNETTE Nerve (acute neuropathies) A 24 years old young male is brought to the casualty • Diphtheria with 2 days history of acute onset, progressive • “Dumb” rabies of all four limbs. At presentation he is bed bound. On examination he has flaccid quadriplegia with swallowing • Porphyria difficulty. What should be the approach to such a patient? • Drugs & Toxins (arsenic, thallium, lead, gold, INTRODUCTION chemotherapy - cisplatin / vincristine) Acute flaccid paralysis (AFP) can be defined as a clinical • Vasculitis (incl. lupus, polyarteritis) syndrome characterized by rapid onset (usually hours to days), progressive weakness of at least one, usually Nerve Roots (acute polyradiculopathies) and plexus lesions two or more limbs. There may be bulbar and respiratory • Guillain-Barre Syndrome involvement. • HIV Accurate diagnosis of the cause of AFP is important for • Other viruses like CMV therapy and prognosis. If untreated, AFP may not only persist but also lead to death due to failure of respiratory • Cauda equina syndrome (lumbar disc, tumour, muscles. It can also cause complications like aspiration etc.) pneumonia, deep venous thrombosis, bed sores and • Sarcoidosis contractures. AFP also is of great public health importance because of its use in surveillance for poliomyelitis in the • Lyme disease context of the eradication initiative. • Plexus lesions (brachial plexitis, lumbosacral plexopathy) NEUROANATOMICAL CORRELATE OF DIFFERENTIAL DIAGNOSIS Anterior Horn Cell Before approaching the given case it is useful to keep some • Poliomyelitis common differential diagnoses in mind as per anatomical • Other viruses like HIV location starting from one end of the neuraxis. • Paraneoplastic Muscle: • Inflammatory myopathy (polymyositis, Spinal Cord dermatomyositis) • Inflammatory (Transverse myelitis) • Viral myositis • Other myelopathies (epidural abscess or hematoma) • Periodic paralyses (hypokalemic, hyperkalemic) • Anterior spinal artery syndrome • Metabolic derangements (hypophosphatemia, CLINICAL CLUES , hypermagnesemia) History: Following points in the history must be enquired into so as to classify the presenting pattern of weakness (as given below). This helps not only finding the underlying • Myasthenia Gravis etiology but also the prognosis and deciding the therapy: • Animal toxins (snake bite especially cobra, krait; • Onset & progression of weakness: sudden, acute shellfish, crab etc) (over hours), subacute (days to weeks) • • duration of weakness (hours to days to weeks) • Tick paralysis • pattern of weakness (eg: proximal, distal) • Organophosphate toxicity (can also cause • pattern of progression (eg: onset in arms, “ascending neuropathy) paralysis”) • Lambert-Eaton Myasthenic Syndrome (LEMS) • sensory involvement (numbness, tingling, loss of balance esp. in dark, pain / burning) 424 • bulbar involvement (change in voice or swallowing) Clues to UMN lesion (mostly a spinal cord lesion) could be presence of either: • facial weakness (trouble chewing, sucking with straw, blowing) • Brisk reflexes • extraocular muscle weakness (diplopia) or ptosis • Extensor plantar • respiratory involvement (iability to complete • Definite sensory level sentences, dyspnea, orthopnea) • Bladder or bowel involvement • bladder or bowel involvement A LMN lesion will have absent reflexes with mute plantar. • autonomic involvement (diarrhea, orthostatic Frequently, an acute onset spinal cord lesion may present dizziness, urinary retention, palpitations) with absent reflexes due to spinal shock. But the presence of other differentiating features (extensor plantar, definite • systemic symptoms (fever, weight loss, rash, joint sensory level and bladder involvement) help localize the pain) lesion to spinal cord. • recent illness or immunization (diarrheal or Step 2: If it is a LMN lesion what is the pattern of weakness? NEUROLOGY respiratory tract infection, anti rabies vaccine, oral Is it proximal or distal? polio vaccine) Lesions localized to the following anatomical locations • recent travel (out of country, to woods [tick bites]) cause proximal, mostly symmetrical weakness in AFP: • recent h/o dog bite • Muscle • precipitating factors (exertion, carbohydrate • NMJ loading - with periodic paralyses) • Polyradiculoneuropathies • fluctuation in weakness (eg. diurnal variation, fatiguability in myasthenia) Poly neuropathy will present with distal, mostly symmetrical weakness. Lesions localized to the anterior • drug or toxin exposure (canned or ‘bad’ food, horn cells can present with symmetrical or asymmetrical, pesticides, lead exposure) proximal, distal or a combination of both. The reflexes • family history (porphyria) will be absent in both the conditions. PHYSICAL EXAMINATION Step 3: Are the reflexes preserved? • Distribution and degree of weakness looking Localization of lesions with proximal weakness and specially for extraocular muscles, facial muscles preserved reflexes include muscle or NMJ. Fatigability and bulbar involvement (appearance of weakness with repeated use) is a prominent • Assess for fatiguability feature in NMJ disorders especially myasthenia. • Sensory impairment: particular modality (vibration Reflexes would be absent in: / proprioception vs. pain / temperature) - is there a • Anterior horn cell disorders sensory level? • Polyradiculoneuropathies • Reflexes: Are the deep tendon reflexes lost? (ie. areflexic), depressed, preserved, or brisk); Do • neuropathies diminished reflexes facilitate with repeated efforts? Step 4: Are sensations preserved? (LEMS) Neuropathies present with sensory involvement. • Autonomic features (postural fall, abnormal Polyneuropathy presents with glove and stocking sensory sweating, pupillary response, ileus) involvement while mononeuritis multiplex would present • Skin: lines on nails with arsenic poisoning (Mee’s with patchy sensory loss. lines), ticks, photosensitivity, Gottron’s papules on Polyradiculoneuropathies may or may not have a sensory extensor surfaces & heliotrope discoloration over loss. Some GBS variants may have sensory loss. Cauda eyelids (dermatomyositis), fang marks equina may present with a sensory loss in a radicular • Spinal tenderness (with epidural abscess or distribution. hematoma, spinal tumour) CATEGORIZATION AS PER PATTERN OF INVOLVEMENT • Straight leg raise (radiculopathy) It is useful to classifying the pattern of involvement into any one of the following given below. This approach CLINICAL CLUES TO DIFFERENTIAL DIAGNOSIS narrows the differential diagnosis further (Figure 1). Step 1: Is it an upper motor neuron (UMN) or a (LMN) lesion? 1. Flaccid symmetric quadripareis (± bulbar and respiratory involvement) with areflexia and minimal to profound sensory loss (but often CHAPTER 89 425 Paraneoplastic syndromes Paraneoplastic Organophosphate toxicity (muscarinic cholinergic overstimulation) Botulism IVIg or plasmapheresis are reversing equally the conditions. However effective the side in effect profile of IVIg is better. IVIg is given in dose of 400 mg/kg /day for 5 days day alternate on done be can plasmapheresis while for 5-6 sessions depending on the response. Indications include weakness Rapidly progressive Presence of respiratory or bulbar involvement is non Not indicated if the degree of weakness progressive and has been present for more than 2 weeks. FURTHER INVESTIGATIONS FURTHER AFP SPECIFIC SOME IN OUTLINE MANAGEMENT • • • It is imperative to have a clinical approach as outlined a clinical approach to have It is imperative above rather than relying only on electrophysiology, lab After the diagnosis. parameters or imaging to aid in the differential diagnosis is narrowed then tests can be done will strategies management Further diagnosis. confirm to depend on the most probable diagnosis. Syndrome Guillain- Barre Specific Measures: • • • 1. 2. • Fig. 1: Flow diagram of approach to acute flaccid paralysis (AFP) acute flaccid paralysis to diagram of approach 1: Flow Fig. sensory symptoms) - Acute neuropathy or sensory symptoms) - polyradiculopathy (eg GBS) Symmetric proximal muscle with preserved and signs or symptoms sensory weakness without reflexes: Acuteperiodic paralysis myopathy (eg. polymyositis); Fatiguable muscle weakness with diplopia, ptosis and bulbar dysfunction (eg myasthenia and other neuromuscular disorders) Flaccid Paraparesis with sensory level (often with dysfunction) bladder & reflexes limb lower reduced thoracic spinal (painful), - Cauda equina syndrome cord spinal myelitis, (eg. transverse lesions cord infarct) Bulbar predominant involvement: Botulism gravis Myasthenia GBS Snake bite Ophthalmoplegia with motor weakness: of GBS (areflexia) Miller-Fischer variant Botulism & Tick paralysis Snake Bite Prominent autonomic dysfunction: GBS 2. 3. 4. 5. • • • • 6. • • • 7. • 426 Supportive Measures: 1. Thymic mass is demonstrated on a CT chest • Air way protection 2. If no thymic mass then if age is between 10 to 55 years • Cardiovascular monitoring for autonomic dysfunction POLYMYOSITIS • Enteral feeding if oropharyngeal dysfunction • Steroids are started as soon as the diagnosis is present confirmed. • Nutrition and daily fluid balance in ICU patients • On follow up once improvement starts steroid sparing immune suppressants like azathioprine or • Correction of electrolyte imbalance and conditions mycophenolate etc are added. like SIADH • Early rehabilitation is needed • Heparin/ LMWH for prevention of DVT HYPOKALEMIC PERIODIC PARALYSIS • Prevention of bed sores • Correction should start with oral therapy of 15 • Early rehabilitation ml solution of KCl (diluted) and can be given as NEUROLOGY frequent as 30 minutes till improvement starts. MYASTHENIA GRAVIS • Steroids are the main stay. However should start at • IV replacement is usually not necessary and low dose and then gradually build up indicated if there is swallowing difficulty or vomiting. • Immunosuppressants like azathioprine may be added subsequently as steroid sparing agents. • Long term therapy consists of acetazolamide in Other drugs like mycophenolate also are a good doses from 250 mg-1000 mg/day. option REFERENCES • Acetyl Coline esterase inhibitors like pyridostignine 1. Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson (60 mg tablet) or neostigmine (15 mg tablet) are JL, Loscalzo J (editors). Harrisons Principles Of Internal started along with steroids and titrated as per Medicine.19th Ed.New Delhi:Mc Graw Hill;2015. requirement. 2. Campell WW. DeJong’s The Neurologic Examination. 7th Ed. Lippincot Williams Wilkins; 2012. • IVIg (400 mg/kg / day X 5 days) or plasmapheresis is indicated if patient presents in crisis or impending 3. Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL (editors). Bradley’s Neurology in Clinical Practice. 7th Ed. crisis. Presence of respiratory distress defines the Elsevier;2016. presence of crisis • Patient may be referred for thymectomy if they have generalized disease and