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Home , Myotonia congenita, Neuromuscular disease, Spasm

Neuromuscular with abnormal 11/30/17 movement

Cramp

• Episodic and involuntary • Associated with with abnormal movement • Occur in shorten position and contracting muscle • Motor neuron hyperactivity causing sustained muscle Charungthai Dejthevaporn, MD, PhD, FRCP(T), FRSM • Preceded by or muscle twitching du to repetitive Consultant Neurologist, Department of Medicine contractions of motor units Head of Clinical Neurophysiology Unit, EMG Laboratory and • High frequency discharge (20-150 Hz) on EMG Neuromuscular Clinic Section, Queen Sirikit Medical Center Faculty of Medicine, Ramathibbodi Hospital Mahidol University, Bangkok, Thailand

Classification of Classification of Cramp

• Paraphysiological cramp • Idiopathic • occur in healthy person related to specific physiology circumstances • Sporadic • pregnancy or exercise • Cramp- syndrome • hyperexcitability of terminal branches due to continued muscle use • -hyperhydrosis syndrome

• Inherited • Familial nocturnal

Classification of Cramp Classification of Cramp • Symptomatic cramp • Symptomatic cramp • CNS : • , Parkinson’s disease • Hydroelectrolyte disturbances • hypo-Mg++ • PNS : • dehydration • , neuropathy, radiculopathy, plexopathy, • Heat cramp, perspiration • hyper-hypo Na+, K+, Ca++

• Cardiovascular disease • Endocrine-metabolic condition • arterial or venous disease • hypo- hyperthyroid • hypo-hyperparathyroidism • Toxic/ • uremia and dialysis • statin, fibrate, diuretic • cirrhosis • hypoadrenalism

Charungthai Dejthevaporn 1 Neuromuscular disease with abnormal 11/30/17 movement

Specific muscle associated with and muscle cramps • • Do not occur at rest • Muscle • Develop during exercise • : MC (Becker, Thomsen) • Related to muscle damage • : PMC, hyperKPP • • : hypoKPP Leading to myoglobinuria and acute tubular necrosis • • Metabolic Electrically silent on EMG • Glycogen metabolism disorder • Lipid metabolism disorder

Disorder of glycolytic or glycogenolytic Contracture enzyme defect • McArdle disease • Painful contracture • myophosphorelase deficiency • Metabolic myopathy – glucose metabolism • Tarui disease • Sodium – • phosphofructokinase deficiency • Hypothyroid myopathy • Rippling muscle disease • • Painless contracture • Progressive • (damage of descending motor pathway) – muscle stiffness, cramps • Painful contracture and • Prolonged muscle immobilization

McArdle’s disease Forearm exercise test

• Myalgia and painful muscle cramps • Baseline lactate and ammonia level • develop within minutes only after forceful exercise • Isometric handgrip contraction • Resolve with rest • • Improve after warm up period of non-exhausting exercise (second wind measure lactate and ammonia level at 1,2,4,6 and 10 minutes phenomenon) • Normal : 3-5 x elevation of lactate and ammonia within 5 min of exercise and return to baseline level within 30 min • Hand cramp posture (similar to focal or ) • No elevation of lactate in muscle glycogenosis • after forearm exercise test for lactate production • after performing repetitive gripping movements

Charungthai Dejthevaporn 2 Neuromuscular disease with abnormal 11/30/17 movement

Hypothyroid myopathy or capopedal spasm

• Myalgia • Continuous tonic spasm of muscle • Muscle cramp • motor unit hyperactivity • • Paraesthesia • sensory hyperactivity • Muscle stiffness and slow movement • Worsened by cold • Myoedema

Rippling muscle disease Caveolinopathy

• Painful muscle stiffness, contractures and rippling movement in Caveolin 3 : Component of muscle fibre membrane muscles 4 major phenotypes • Induced with muscle stretching by either voluntary contraction or percussion • LGMD 1C • Myoedema • Distal Myopathy • Electrically silent on EMG • Raised CK • Rippling muscle disease

Myotonia Myotonic disorder

• Phenomenon of impaired relaxation of the muscle after forceful • Acquired myotonia voluntary contraction • drugs • Repetitive of muscle membrane • malignancy • Warm up phenomenon • Paramyotonia – worse with cold temperature • Genetic myotonia • Myotonic dystrophy (DM1, 2, 3…) • Spontaneous discharges of muscle fibers on EMG • Non-dystrophic myotonia • waxing and waning of amplitude and frequency with high firing rate between • (chloride channel) 20-150 Hz • Paramyotonia congenita (sodium channel) • hypoKPP (calcium channel)

Charungthai Dejthevaporn 3 Neuromuscular disease with abnormal 11/30/17 movement

Myotonia Congenita Myotonia congenita Features Thomsen’s disease Becker’s disease Clinical features Inheritance Dominant Recessive • Myotonia with warm up phenomenon Onset Infancy or Early First decade (4-12 years) childhood • Muscle hypertrophy Distribution Face, arms > legs Legs > face, arms • Pain/ stiffness Myotonia Warm-up phenomenon Warm-up phenomenon • Transient weakness Precipitants Rest Rest • Dominant Thomson’s Additional symptoms None Transient; progressive • upper > lower limb; early age of onset from 2 years weakness • Recessive Becker’s Routine EMG Myotonic discharge Myotonic discharge Cold immersion No CMAP amplitude No CMAP amplitude • Lower limb > upper limb; transient weakness on initiation of movement; muscle hypertrophy; age of onset from 4 neurophysiology decrement with cooling decrement with cooling years Treatment Mexilitine, Mexilitine, phenytoin Channel affected Cl- Channel Ch 7q Cl- Channel Ch 7q

Paramyotonia Congenita Features Paramyotonia congenita PMC Inheritance Dominant Onset Birth/infancy • associated with episodes of weakness Distribution Face, tongue, arm • as a result of a persistent inward current causing depolarization of the muscle Myotonia Paradoxical worsening membrane Precipitants Cold and exertion • overlap with HyperPP Additional symptoms Cold induced weakness • presence of paradoxical eye closure myotonia - specific Some with periodic Routine EMG Myotonic discharge Cold immersion neurophysiology CMAP amplitude decrease with cooling Treatment Mexilitine, acetazolamide

Channel affected Na+ channel

SCM (SCN4A myotonia) Peripheral nerve hyperexcitability syndrome • Continuous motor unit and muscle fiber activity • Painful myotonia is more prevalent and severe generated by discharges in motor axon • prominent eyelid/ facial myotonia • Evident at rest and during sleep • Myokymia • dietary triggers (potassium sensitive myotonias) • Clinically visible undulating, wave like or worm like rippling of muscle • can have neonatal onset • EMG findings of continuous muscle fiber activity with doublet, • Neonatal triplet, and multiple motor unit discharges • Neonatal stridor • Fasciculations • Episodic neonatal • • repetitive trains of high frequency discharges • After discharges following voluntary contraction, peripheral nerve stimulation, and gentle percussion of peripheral nerve • Delayed muscle relaxation

Charungthai Dejthevaporn 4 Neuromuscular disease with abnormal 11/30/17 movement

Causes of peripheral nerve hyperexcitability Causes of peripheral nerve hyperexcitability • Inherited disorders • Nerve injury • Episodic type 1 with myokymia (Kv1.1; KCNA1) • Radiation toxicity • Benign familial neonatal epilepsy and myokymia • Inherited neuropathies (CMT II) • (KCNQ2) • Hereditary myokymia without central features • Inflammatory demyelinating neuropathies • Familial cramp syndrome • Multiple sclerosis (facial myokymia) • Toxins • Conduction block neuropathy • Acetylcholinesterase inhibitors • Focal compression neuropathy • Gold • Chronic motor nerve disorders (ALS) • Toluene • Amyloidosis • Oxaliplatin (Wilson et al., 2002) • Uremia • Timber rattle snake venom • Black widow spider venom (α--latrotoxin) • Green mamba venom (α-dendrotoxin)

Causes of peripheral nerve hyperexcitability Schwartz-Jampel syndrome • Autoimmune disorders • Acquired neuromyotonia (Isaacs syndrome) • Rare condition presents in childhood with continuous and generalized muscle • Morvan syndrome activity • Cramp-fasciculation syndrome • Neuromyotonia on EMG • Paraneoplastic neuromyotonia • Thymoma (with or without ) • Skeletal abnormality • Small-cell lung carcinoma • Facial blepharophimosis and dimpling of the chin (caused by continuous • Associated with other autoimmune conditions contraction of facial muscles) • Myasthenia gravis • Guillain–Barre´ syndrome or Chronic Inflammatory • Slow movement due to delay muscle relaxation (ongoing muscle activity and after • Demyelinating (CIDP) discharges) • Systemic lupus • Mutation in the gene encoding the basement membrane protein perlecan that • Multiple sclerosis anchors acetylcholinesterase to the synaptic memebrane in NMJ • Penicillamine • • Other disorders Persistent cholinergic activation of NMJ • Benign fasciculation syndrome • Benign focal myokymia

Charungthai Dejthevaporn 5 Neuromuscular disease with abnormal 11/30/17 movement

Localized peripheral nerve hyperexcitability Hemi-masticatory spasm

• Focal myokymia and neuromyotonia from radiation • Involuntary painful spasm of jaw closure due to unilateral contraction • of temporalis and masseter muscles • Hemi-masticatory spasm • Triggered by chewing or talking • Trigeminal neuropathy • Associated with facial hemiatrophy, a localized from of scleroderma (the Parry Romberg syndrome)

Kennedy’s disease syndromes in peripheral neuropathies • X-linked bulbospinal muscular • Neuropathic • Age 35-60 years • Symmetrical proximal • • Peri-oral fasciculations • Dystonia • Bulbar dysfunction • Focal • 50% Gynecomastia • Painful legs moving toes • 50% sensory neuronopathy • Restless leg syndrome • Postural tremor • Trinucleotide expansion in the Androgen Receptor (AR) gene • Polyglutamine expansion in the protein CAG • Normal 9-36, mutant 40-62 CAG repeats

Stiff person syndrome Facioscapulohumeral Dystrophy • Typical clinical characteristic in many patients • Intermittent muscle stiffness and spasms • Periscapular weakness • axial and proximal limb • Triggered by external stimuli • Beevor’s sign (umbilicus move upward when flex trunk due to lower abdominal muscle weakness) • Variants • Autoimmune • Very early onset • Anti-GAD: • Absence of facial weakness • Abdomen, neck, and thoracolumbar regions • Scapuloperoneal syndrome • Episthotonus posture • Presentation with • Amphiphysin • Asymmetry • arm and neck muscle • Unilateral wing scapula (may misdiagnosed as long thoracic • Associated with CA lung and breast neuropathy) • Inflammatory biopsy

Charungthai Dejthevaporn 6