II. Differential Diagnosis: Cutaneous (Dermatomyositis)
III. Differential Diagnosis: Muscular Disorders
- Myotonia (Muscle stiffness)
- Spinal Muscular Atrophy
- Critical Illness Myopathy
- 
                          Myositis
                          - Polymyositis
- Inclusion body Myositis
- Necrotizing Myositis
 
- 
                          Muscular Dystrophy
                          - Becker Muscular Dystrophy
- Limb-Girdle Muscular Dystrophy
- Myotonic Dystrophy
 
IV. Differential Diagnosis: Nerve Disorders
- Combined Upper Motor Neuron and Lower Motor Neuron
- Upper Motor Neuron disorders
- 
                          Lower Motor Neuron disorders- Myasthenia Gravis
- Lambert-Eaton Syndrome
- Guillain-Barre (other autoimmune polyneuropathies)
- Neuropathy
 
V. Differential Diagnosis: Endocrine and Metabolic Disorders
- Electrolyte
- Thyroid and Paraythyroid Disorders
- Adrenal Disorder
- 
                          Disorders of Energy Metabolism (e.g. Glycogen Storage Disease)- McArdle's disease (Glycogen Phosphorylase Deficiency)
- Adult acid maltase deficiency
- Carnitine-palmitoyltransferase deficiency
 
VI. Differential Diagnosis: Toxic Myopathy or Neuropathy
- See Medication Causes of Myositis
- Steroid Myopathy
- Acute Rhabdomyolysis
- Amyloidosis
- Porphyria
- Organophosphate Poisoning
- Botulism
- Substances of Abuse- Alcoholic Myopathy or Neuropathy
- Volatile Inhalant Abuse (Toluene in glues)
- Cocaine
 
- 
                          Heavy Metal Poisoning
                          - Arsenic Poisoning
- Lead Poisoning
- Mercury Poisoning
- Thallium Poisoning (contained in rat poisons)
 
- Venoms
