Motor Neuron Disease Motor Neuron Disease • Incidence: 2-4 per 100 000 • Onset: usually 50-70 years • Pathology: – Degenerative condition – anterior horn cells and upper motor neurons in spinal cord, resulting in mixed upper and lower motor neuron signs • Cause unknown – 10% familial (SOD-1 mutation) – ? Related to athleticism Presentation • Several variations in onset, but progress to the same endpoint • Motor nerves only affected • May be just UMN or just LMN at onset, but other features will appear over time • Main patterns: – Amyotrophic lateral sclerosis – Bulbar presentaion – Primary lateral sclerosis (UMN onset) – Progressive muscular atrophy (LMN onset) Questions Wasting Classification • Amyotrophic Lateral Sclerosis • Progressive Bulbar Palsy • Progressive Muscular Atrophy • Primary Lateral Sclerosis • Multifocal Motor Neuropathy • Spinal Muscular Atrophy • Kennedy’s Disease • Monomelic Amyotrophy • Brachial Amyotrophic Diplegia El Escorial Criteria for Diagnosis Tongue fasiculations Amyotrophic lateral sclerosis • ‘Typical’ presentation (60%+) • Usually one limb initially – Foot drop – Clumsy weak hand – May complain of cramps • Gradual progression over months • May be some wasting at presentation • Usually fasiculations (often more widespread) • Brisk reflexes, extensor plantars • No sensory signs; MAY occasionally be mild symptoms • Relentless progression, noticable over weeks/ months Bulbar MND • Approximately 30% of cases • Onset with dysarthria, dysphagia • Bulbar and pseudobulbar symptoms • On examination – Dysarthria – Tongue wasting, fasciculation – Brisk jaw jerk – May be other limb symptoms (but not always) • Progression more rapid than ALS presentation • Worse prognosis (approx 2 years) Other presentations • Primary lateral sclerosis (5%) – Pure UMN onset • Progressive muscular atrophy (5%) – Pure LMN onset – May be ‘flail limb’ appearance • Probably slightly better prognosis Progressive bulbar palsy Difficulty breathing Muscle weakness Motor neuron disease II Differential diagnosis • Diagnosis is clinical – EMG/ imaging may help • MND is fatal – exclude other, less severe/treatable conditions – Multilevel cervical/ lumbar degerative changes • May cause myelopathy + LMN features and fasciculation • Usually have sensory symptoms – Benign fasciculation syndrome – Bulbar – cerebrovascular disease, MND – Multifocal motor neuropathy – Hereditary spastic paraplegia – Kennedy’s disease (SMA) Investigations • Clinical diagnosis • Check CK – modest elevation • Investigations often aimed at excluding other causes – Often MRI cervical/lumbar spine – May image brain • NCS/ EMG show “chronic active denervation” in areas supplied by multiple nerve roots (note this pattern may be seen in one territory by radiculopathy) • Tongue/ Sternomastoid EMG sometimes performed Treatment • Riluzole – Glutamate antagonist – May extend left expectancy slightly (3-5 months on average) – Low side effect profile • Occ nausea, fatigue • Can disturb LFTs (needs monitoring at onset) – Expensive (?cost/ benefit) • Palliative – Nutrition • Soft diet • ‘Chin tuck’ – Hyoscine (excessive secretions/salivation) – Opiates/ benzodiazepines MND dementia • Proportion of patients develop frontotemporal dementia – Flat affect – Disinhibition – Language disturbance/ dysphasia – Impaired ‘executive function’ Cervical spondylomyelopathy vs Motor neuron disease • Flaccid weakness UL, shoulder girdle • Wasting of all small hand muscles • Inverted supinator • MyeloCT scan – spinal stenosis C4-C6 • EMG – denervation of UL muscles Motor Neuron Disease • Look for signs • Differential diagnosis • Counselling • Good luck.