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Neurology Differential Diagnosis Differential Diagnosis in Neuropathy, Supranuclear Palsy and Adult Onset Muscular Dystrophy Rivera November 5, 2024 Objectives 1. Differentiate between the various polyneuropathies Large fiber, smal...

Neurology Differential Diagnosis Differential Diagnosis in Neuropathy, Supranuclear Palsy and Adult Onset Muscular Dystrophy Rivera November 5, 2024 Objectives 1. Differentiate between the various polyneuropathies Large fiber, small fiber and autonomic 2. Apply knowledge of needle EMG and nerve conduction velocity in the diagnosis of peripheral neuropathy and muscular dystrophy 3. Differentiate between the various adult onset muscular dystrophies by clinical presentation Electrodiagnostic studies in the peripheral nervous system Needle EMG can be is used to diagnose nerve and muscle disorders, spinal nerve root compression, and motor neuron disorders such as amyotrophic lateral sclerosis. Electrodiagnostics can….. Muscle disorders: Distinguish between muscular dystrophy, polymyositis, or motor problems like involuntary twitching (not able to differentiate between within muscular dystrophy) Nerve injuries: Such as carpal tunnel syndrome, sciatica, or nerve root injuries Neuromuscular diseases: Myasthenia gravis, or diseases that affect the connection between nerves and muscles Degenerative conditions: Amyotrophic lateral sclerosis (ALS) or other degenerative nerve diseases Spinal cord diseases: Such as a herniated disc When in doubt about strength, provide repeated muscular testing to pick up motor unit fatigue. Nerve conduction studies Nerve conduction studies involve stimulating motor, sensory, or mixed nerves through the skin with a small pulse of electrical current. Recording electrodes, placed on the skin over nerves and muscles innervated by the stimulated nerve trunk, capture electrical responses generated by the stimulation. INTERPRETING THE RESULTS Nerve conduction studies and needle electrode examination can help address the following questions: Where is the lesion? Is it in the nerve root, plexus, peripheral nerve, neuromuscular junction, or muscle? What is the pathophysiologic nature of the disorder? If neuropathy, is it due to demyelination or to axon loss? If myopathy, is it due to inflammation and necrosis? What is the chronicity of the problem? Is it acute, subacute, chronic, or chronic with ongoing denervation? What is the electrical severity of the problem? Electrodiagnostic testing can also reveal specific clues to etiology, such as myotonia in a patient with suspected myopathy.  LIMITATIONS OF ELECTRODIAGNOSIS Electrodiagnosis has limitations. Nerve conduction studies assess the integrity of only large-diameter axons. It gives clues, but not a specific diagnosis Electrodiagnostic testing helps locate problems and objectively measures a portion of the peripheral nervous and neuromuscular systems. It does not usually identify the specific underlying cause of a condition and is best viewed as an extension of the physical examination. It is less useful for elderly patients Nerve conduction studies are less reliable in advanced age. For example, sensory responses are not obtainable in the lower limbs of many healthy adults over age 75, making electrodiagnostic testing less useful for diagnosing polyneuropathy. It does not reveal much about the central nervous system Electrodiagnostic testing does not adequately assess the central nervous system. It may demonstrate nonspecific abnormalities in central nervous system disorders, but findings cannot be used to definitively locate or diagnose a central nervous system lesion. Surface Electromyography Surface EMG provides information about patterns of muscle firing, including details about irregularities and weakness of the firing, which in turn offers information about muscle impairments caused by an injury or disease. The main impediments to the increasingly widespread use of sEMG are the lack of clinicians trained in its use and, more broadly, a lack of recognition of its clinical value (Campanini et al., 2020). At this point, because of the limited amount of clinical experience with the technique, there is little known about the limitations of sEMG’s diagnostic or evaluative efficacy. Polyneuropathy  Symmetrical neuropathies (chronic) Diabetes Mellitus: 1 in 5 persons Alcohol Abuse Autoimmune conditions: RA, Sjorgrens, SLE Bacterial and viral infections Bone marrow disorders Polyneuropathi Carcinoma es Radiation and Chemotherapy Hepatitis B and C Hypothyroid disease Kidney disease Liver Disease Medication (statins) Nutritional deficits B vitamins (1,6,12 and E)  Large fiber Demyelinating Axonal Types of Sensory only Polyneuropat Motor only hy Sensorimotor Small Fiber Autonomic  Polyneuropathy involving Autonomic Nervous System HEAT UNUSUAL DIZZINESS BLOOD BLADDER INTOLERANCE SWEATING PRESSURE PROBLEMS ANOMALIES Charcot Marie Tooth Hereditary Neuropathy  Pearls in differential diagnosis in polyneuropathy If sensory fibers are involved, sensory symptoms should be characterized such as prickling, tingling, or buzzing, vs those with a negative sensation, such as loss of sensation or imbalance. This differentiation is helpful because these positive sensory symptoms often suggest a neuropathy is Differential Diagnosis based upon symptoms  EMG cannot evaluate small fiber neuropathy Idiopathic polyneuropathy Pain is one the prominent problems in 20% of cases: small fiber Higher risk for falls sensory neuropathy Safety for integumentary Glove and stocking presentation Examination basis for polyneuropathy Observation: muscle wasting Sensory exam: Pin and cotton swab: discerning sharp or dull and the location -Two point discrimination Vibratory sense Distal> problems than proximal Gait (FGA) Balance (SOT) What is this diagnosis? After initially presenting to their primary MD, she was referred to a neurologist for the following signs and symptoms over the previous year: persistent pins and needles in the feet bilaterally, balance disturbances, pain in the lower extremities and muscle cramping. She fractured their wrist due to a fall 1 year ago and received physiotherapy treatment for a sprained ankle 1.5 years ago but is otherwise healthy. They are not currently on any medications and have been referred to physiotherapy for treatment. Adult onset Muscular Dystrophy Myotonic Dystrophy Becker’s Muscular Dystrophy Fascioscapulohumeral Dystrophy Myotonic Dystrophy Type 1 (adult onset) Most common form of adult Muscular Dystrophy Onset in the 2nd to 3rd decade-autosomal dominant Variable presentation Classic sign is unable to relax muscules (prolonged activation) Unable to let go of someone’s hand with a handshake Effects musculature and organs Nervous system (daytime sleepiness), cerebral atrophy Involuntary muscle weakness-dysphagia, constipation, gallstones Weakness of the face, neck, fingers Cardiac conduction or respiratory conditions can occur Needle EMG is able to differentially diagnose DM type 1 Focus on Adult-Onset Muscular Dystrophy Becker MD: onset 11 – 25 years of age : Similar to Duchenne’s MD but slower progression. -Variable progression (w/c to cane) -normal lifespan : Initial proximal presentation : X-linked, dystrophin gene mutation Classic sign of hypertrophy of calves Fascioscapulohumeral Muscular Dystrophy (FSHD) Most prevalent type of adult onset MD (various genetic and sporadic presentations) Onset before 20 (90%) decade of life up to 50 years of age: slow progression and over a lifetime. Normal lifespan Women>Men, less severe pathology and at later age Involvement of face (smile, whistle, close eyes), scapula and shoulder musculature with asymmetrical appearance Presentation is weakness of the mouth and eyes, shoulders and later peroneals Chronic pain is common Limb Girdle Muscular Dystrophy A childhood and adult onset – genetically diverse diagnosis with onset from 1 to 50 years of age 33 (and more to come) different genetic variations of LGMD Variability even within families Two types LGMD 1 and LGMD 2: LGMD 1 is the adult form (autosomal dominant) Pelvic muscles become weak (difficulty climbing stairs) Walking becomes more difficult Not healing from an injury or longer heal time from surgery Falling down and not being able to stand up  Differential: diabetic neuropathy, low back pain Limb Girdle Catching breath after walking Muscular across the street Dystrophy Unable to wash hair( fatigue) Clinical Presentation Rapid fatigue First signs difficulty walking across street Slurred speech Tightness in achilles Different variants have hypertrophy gastrocs Males=females Degenerative disease Differential between PSP and MSA Is this Parkinson’s disease? Jim is a 67 year old retired farmer that lives with his wife Julia. During the past 2 years Jim has noticed a gradual decline in his balance, culminating in 3 falls at home this month. Jim’s wife Julia has also noticed that Jim is walking much more slowly during their walks together. In addition, Jim has noticed some difficulty reading his newspaper due to self-reported mildly blurred vision, and he also experiences some mild intermittent tremors in his right and left hands. Jim finds these tremors most noticeable when he holds the newspaper. Jim’s relationship with his wife is becoming strained, which Julia attributes to Jim being more irritable than he used to be. Jim has also complained of an increasingly stiff neck over the past year, which he finds uncomfortable and interferes with his ability to sleep at night. With symptoms becoming increasingly difficult to manage and significant concern over increasing frequency of falls, Jim went to see his family doctor Progressive Supranuclear Palsy Known as a Parkinson-plus disorder: PSP is a rare neurological disorder that is usually associated with impaired gait and movement, balance issues, axial rigidity, vision problems, speech and swallowing deficits, as well as mood and cognitive impairments or changes Eye movements: Difficulty controlling eye movements, including looking up or down, and involuntary closing of the eyes Behavior: Irritability, apathy, unusual emotional outbursts, or impulsive behavior https://youtu.be/4H2BJvd9bEM?si=UMi6KmtxZmWvmF A0 How to compare PD versus Supra Nuclear Palsy Cervical extension rigidity with lack of forward head posture Swallowing issues with high risk of pneumonia and aspiration Loss of downward gaze and saccades loss of vertical component https://youtu.be/LU7TC0wufhg?si=bLKPjmbwJR20-scp Earlier loss of protective extension backwards and backwards step Faster disease progression Multiple System Atrophy Rare and progressive brain disorder. Progressive loss of spinal and brain nerve cells: initially the diagnosis is very similar to Parkinson’s disease. Etiology: unknown, sporadic disease. Differential difficult Onset: 50 years of age: rapid course of disease 5-10 years Characterized by autonomic symptoms, parkinsonism and ataxia. No blood tests or MRI can diagnose. Two major subtypes: Parkinsonism and ataxic MSA. The clinical diagnosis of probable MSA requires a reduction of systolic blood pressure by at least 30 mm Hg or of diastolic blood pressure by at least 15 mm Hg after 3 minutes of standing from a previous 3-minute interval in the recumbent position. Multiple System Atrophy Autonomic System Involvement MSA has alpha-synuclein in the glia cells – causes demyelination and astrogliosis. Multiple System Atrophy Cerebellar Parkinsonism Trouble with coordination Rigidity and tremors Changes in vision (double Slow movement patterns vision) Hand stiffness Dysarthria and dysphagia Bladder involvement Voice changes Overview Students will be able to Know the diagnostic capability of EMG Differentiate between the adult onset muscular dystrophies by clinical presentation of muscular groups Understand the various clinical classification of polyneuropathy -vascular -infectious -neoplastic - metabolic