Motor Neuron Disease

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Motor Neuron Disease:

Motor Neuron Disease Dr Rahul Chakor MD., DM Assoc Prof of Neurology T. N. Medical College B. Y. L. Nair Hospital Mumbai

Famous People:

Famous People

Motor Neuron Disease (MND):

Motor Neuron Disease (MND) Amyotrophic lateral sclerosis (ALS) MND Lou Gehrig disease (New York base ball hitter) UMN + LMN features

Outline of Talk:

Outline of Talk Introduction Symptomatology Pathophysiology Etiology Diagnostic Criteria Treatment Other Issues

Introduction:

Introduction Upper Motor Neuron Loss of dexterity Loss muscle strength (Weakness) Spasticity (Stiffness) Hyper - reflexia Pathological reflexes Pseudobulbar palsy Lower Motor Neuron Loss of muscle strength (Weakness) Wasting (Muscle atrophy) Hyporeflexia Muscle hypotonicity (Flaccidity) Fasciculations

Introduction:

Introduction Serious and fatal Degeneration of upper and lower motor neurons Pyramidal Cells, cranial nerve nuclei, anterior horn cells (spinal motor neurons) Progressive weakness, wasting and fasciculations

Introduction:

Introduction Jean Martin Charcot - 1869 Lou Gehring Disease, Classical amyotrophic lateral sclerosis of Charcot (ALS)/Spinal onset form – 1929 (60% presentation) Variations – AT PRESENTATION *Progressive bulbar palsy (20% presentation) *Primary Lateral Sclerosis *Progressive Muscular Atrophy (10% presentation) Progression to involve AHC, Pyramidal cells, Cranial nerve nuclei

Epidemiology:

Epidemiology Incidence - 2 per 100,000 population/year Prevalence - 3 to 8 per 100,000 Onset age Mean: 46 to 63 years Male : Female 3:1

Clinical features:

Clinical features Typical pattern (60%) * Upper + Lower motor neuron signs with normal sensation * Spinal form

Weakness:

Weakness Weakness – 60% presentation Limb weakness Early patterns Asymmetric May involve proximal or distal musculature Specific patterns Upper > Lower extremity Distal lower extremity

Weakness:

Weakness Focal distal UL weakness in segmental, nerve distribution – pseudoneuritic presentation Single upper limb weakness – Monomelic presentation Bilateral upper limb proximal – Man in Barrel Weakness on one side – Mills hemiplegic variant Respiratory muscle weakness – Dyspnea onset

ALS:

ALS

Bulbar dysfunction:

Bulbar dysfunction Bulbar dysfunction Most commonly associated with upper motor neuron dysfunction Frequency More common in older females: 50% with bulbar presentation Bulbar signs at onset: 20% to 30% of all sporadic ALS cases

Bulbar dysfunction:

Bulbar dysfunction Dysarthria * Speech rate: Slow *Speech pattern: Slurred; Short phrases; Inappropriate pauses *Voice quality: Reduced; Hypernasality; Reduced range of pitch & loudness Dysphagia * Aspiration *Food types: Dry, Tough-textured or *Crumbly; Thin liquids *Eating time: Increased *Saliva: Poor swallowing, Droolong

Bulbar dysfunction:

Bulbar dysfunction Emotional lability/"Pseudobulbar" affect Difficulty with voluntary coughing Laryngospasm (20%) Jaw Reflex: Brisk Difficulty closing Tongue Movements: Slow Bulk: Often relatively preserved for degree of dysfunction

Bulbar Palsy:

Bulbar Palsy

Respiratory failure:

Respiratory failure Respiratory failure *May occur in isolation *Frequent association: Arm weakness *Early stages often asymptomatic *Early event: Hypoventilation Occurs first in REM sleep Accessory muscles of respiration become flaccid * Dyspnea *Sleep disorders *Morning headache *Ineffective cough: Weakness of expiratory muscles

Weakness:

Weakness Areas of weakness with some specificity for ALS * Very proximal denervation Paraspinous Posterior neck *Jaw weakness: Closure; Opening *Voice Nasal, slurred speech Continuous emission of sound *Tongue Weak Movement - Slow ,Reduced amplitude Relatively preserved bulk: Often Movement of jaw with tongue Jaw reflex: Hyperactive *Isolated respiratory failure

Wasting:

Wasting Muscle wasting *Often present early in disease course *Usually associated with Weakness Progression: Regional (Arms, Legs or Bulbar) *Symptoms usually progress first in already affected region *Continuous progression once region (bulbar, arms, or legs) involved *Other regions involved later Spread usually to adjacent region No predictor of time of involvement *Periods of symptomatic stabilization may occur *Remissions in symptoms or signs rare

Other features:

Other features Spontaneous motor activity Cramps Common in legs, at night Often resolve spontaneously with disease progression May be severe later in disease: Associated with prominent spasticity Fasciculations ALS rarely presents with fasciculations in the absence of weakness Pathogenesis: ? Greater persistent Na+ conductance in motor axons Pain: Related to immobility Behavioral Cognitive change: Frontal lobe dysfunction (mild) not uncommon Pseudobulbar affect: Unprovoked laughing & crying; Common with bulbar involvement Dementia: 3% to 5% Rarely involved: Bladder; bowels; Autonomic; Extraocular movements; Sensory

Diagnostic criteria:

Diagnostic criteria Clinical exam, EMG and pathology Definite ALS : Progressive disease with Upper & lower motor neuron signs in bulbar & 2 spinal regions, or Upper & lower motor neuron signs in 3 spinal regions Probable ALS : Progressive disease with Upper & lower motor neuron signs in 2 regions and Upper motor neuron signs in a region rostral to the lower motor neuron signs

Upper motor neuron :

Upper motor neuron Anatomic patterns Bulbar: Causes most tongue & bulbar dysfunction Paraparesis Asymmetry: Common in limbs, especially early in disease Cortical hemiparetic: Occasional Tendon reflexes Hyperactive (100%): In areas with normal strength and weakness More common sign than upgoing toes (30% to 50%) Bulbar involvement associated with emotional lability (75%) May cause disability without associated weakness: Especially in legs Laboratory correlates: Abnormal MR spectroscopy Transcranial magnetic stimulation

Motor System:

Motor System

Pyramidal System:

Pyramidal System Pyramidal Cell Motor Neuron

MRI:

MRI Control Control Patient T1 Spin Echo MTC FLAIR FLAIR

MRI:

MRI T1 Spin Echo MTC FLAIR Control Patient

Slide 27:

The four regions are bulbar, cervical, thoracic, and lumbosacral. The second part of the diagnostic evaluation requires an absence of electrophysiologic evidence that might explain the signs of LMN degeneration, and an absence of neuroimaging evidence of other disease processes that might explain the observed clinical or electrophysiologic signs. ALS is a diagnosis of clinical presentation but is also a diagnosis made by exclusion of possible diseases.

Slide 28:

glutamate antagonists in treating ALS and to the approval of riluzole (Rilutek), Adverse reactions include increases in alanine aminotransferase (ALT) and aspartate aminotransferase (AST); Vitamin C (1000 mg) and vitamin E (400 IU twice daily) along with a general multiple vitamin are often prescribed by ALS centers for the nutritional enhancement and antioxidant potential.

Thank You:

Thank You