EMG in Motor Neuron Disease. Randall L. Braddom, M.D., M.S.

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1 EMG in Motor Neuron Disease Randall L. Braddom, M.D., M.S.

2 Definition Motor Neuron Diseases are diseases or conditions that produce dysfunction of the anterior horn cells, which then results in weakness and muscle wasting.

3 Motor Neuron Diseases Are also called: Spinal Muscular Atrophies Motor Neuronopathies

4 Many Classifications Abrams Dubowitz and Emery Swash and Schwartz

5 Type I: Werdnig-Hoffman Infantile Muscular Atrophy Baby usually floppy Mother notes less movement Fasciculation/scalloping tongue Poor breathing and feeding Death in 3 years or less

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7 Formal Diagnostic Criteria Inability to roll or sit at any time Never attaining >250 cc VC Paradoxical breathing One or more episodes of respiratory failure requiring support before 18 mos of age Loss of ability to receive any nutrition by mouth before 24 months of age

8 SMA Type I: Werdnig- Hoffman 1/5,000 live births Begins 2-12 months of age 30% begin in utero Most are Autosomal Recessive on Chromosome 5q13

9 SMA Type I: Werdnig-Hoffman 98% have gene deletions SMA Type I is the most common inherited fatal disease in infants Age at death without respiratory treatment is mean of 9.6 months Can live up to 5 years with respiratory assistance Bach JR et al. Am J Phys Med Rehabil 2007;86:

10 SMA Type I: Werdnig- Hoffmann EDX Fibrillations Marked reduction in # of MUAP s Motor NCV normal, but low amplitude of evoked response Sensory NCV normal

11 SMA Type II: Werdnig-Hoffman Intermediate Form Onset 2-12 months Can live up to 25 years Autosomal Recessive on Chromosome 5q EDX is the same as Type I

12 SMA Type III: Kugelberg-Welander Aka Juvenile Spinal Muscular Atrophy Onset 2-17 years Usually wheelchair by 30 years of age Usually hyporeflexic (but occasional hyperreflexia) Muscle wasting is often proximal first, causing confusion with muscular dystrophy

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15 SMA Type III: Kugelberg-Welander 50% have elevated CK Autosomal Recessive on chromosome 5q Autosomal Dominant and X-linked recessive forms also reported EDX similar to SMA Type I Have more MUAP s MUAP s larger in duration and amplitude

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18 SMA Type IV: Adult-Onset Progressive Spinal Muscular Atrophy Onset years Progresses slowly Limits ambulation Autosomal Dominant form X-linked Recessive form

19 Kennedy s Disease X-Linked Bulbospinal Muscular Atrophy Begins around years Involves cranial nerves, with shoulder and pelvic girdle muscle weakness Very slowly progressive; often mistaken for ALS

20 Amyotrophic Lateral Sclerosis ALS Lou Gehrig s Disease /100,000 incidence 6/100,000 prevalence Onset years Onset is asymmetrical

21 EL ESCORIAL CRITERIA Developed by the World Federation of Neurology Most widely accepted benchmark for diagnosis of ALS Published: J Neurol Sci 1994:124 (suppl): Consensus update 2006 Awaji-Shima, Japan

22 Awaji-Shima Concensus on El Escorial Criteria for ALS (2006) ALS diagnosis requires: Evidence of LMN degeneration. Evidence of UMN degeneration. Progressive spread of symptoms or signs within a region or to other regions. Diagnostic categories: Clinically definite ALS: UMN and LMN signs in 3 of four regions. Clinically probable ALS: UMN and LMN signs in 2 regions with UMN signs rostral to LMN signs. Clinically possible ALS: UMN and LMN signs in only 1 region, or UMN signs in at least 2 regions, or LMN signs found rostral to UMN signs.

23 Amyotrophic Lateral Sclerosis Can begin in limbs and/or bulbar Bulbar symptoms: voice and swallowing Weight loss can >30% of body weight Ultimately all limbs and bulbar involved Usually combined upper and lower motor neuron syndrome Good article on early patterns: Simon NG et al Muscle Nerve 50:

24 Sporadic ALS Etiology Wijesekera and Leigh possible cellular mechanism etiologies genetic factors excessive glutamate activity oxidative stress mitochondrial dysfunction impaired axonal transport neurofilament aggregation protein aggregation causing cytoplasmic inclusions inflammatory dysfunction deficits in neurotrophic factors

25 Sporadic ALS Risk Factors History of smoking (2X) Current smoker (3X) High dietary fat Low dietary fiber Genetics

26 Amyotrophic Lateral Sclerosis Only rarely affects sensation, sphincter function or autonomics Death in mean 3 years (range 1-7) Course usually longer in younger victims DX: Try to find abnormalities above the foramen magnum, such as fibrillations in the tongue

27 ALS EDX Positive waves, Fibrillations Fasciculations Large polyphasic motor units Marked reduction in # of motor units Reduced recruitment Mild slowing of motor NCV Reduced amplitudes of the combined motor unit potentials

28 Mayo Clinic Study of ALS Misdiagnosis 46 sent to Mayo Clinic with DX of ALS 16 had cervical spondylosis 9 had focal atrophy of limbs due to other causes 5 had neuropathies 4 had meaningless fasciculation 3 had myopathy 2 had MS 7 had miscellaneous diseases

29 Mayo Clinic Advice on ALS Dx Watch the patient over course of time. (No rush to make the diagnosis). Try to find UMN and LMN findings above and below the foramen magnum Nervous patients can have fasciculations and brisk reflexes and muscle pain But no muscle atrophy or EMG changes ALS does not cause muscle pain

30 Familial ALS 5-10% of cases are hereditary Autosomal dominant, chromosome 21 Male/female ratio of 1.2/1 Onset usually years EDX is the same as non-familial ALS

31 Primary Lateral Sclerosis Rare, involves corticospinal tracts more than anterior horn cells Usually has intense spasticity Can last for years Also has sensory abnormalities, cerebellar dysfunction, and some have intellectual deterioration

32 Progressive Bulbar Palsy Similar to ALS, but involves only bulbar muscles Equal gender ratio Many feel that this is actually a variant of ALS 1-2% of ALS cases involving only bulbar muscles More rapid death than regular ALS Also has to be differentiated from Kennedy s Syndrome

33 3 Motor Neuron Diseases with Bulbar Palsy Kennedy s Disease (Slow) ALS (Medium) Progressive Bulbar Palsy (Fast)

34 Focal Motor Neuron Disease Rare Gives only focal weakness Looks like ALS, but never spreads out of one focal area Leaves patient with permanent focal weakness

35 Rare Motor Neuron Diseases Scapuloperoneal Spinal Muscular Atrophy Juvenile Hereditary ALS Progressive Juvenile Bulbar Palsy of Childhood Progressive Bulbar Palsy with Deafness Chronic Distal Progressive Spinal Muscular Atrophy New Ones being discovered each year