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Motor Neurone Disease – Differential Diagnosis

Differential diagnosis for Motor Neurone Disease (MND) for doctors, medical student exams, OSCEs, finals and MRCP (click here for reference)

Key differentials are in bold. The examination/investigation which is most helpful in identifying the mimic is below each differential diagnosis.

  • Cervical radiculopathy
    • MRI spine shows multi-level disc compression
  • Syringomyelia
    • MRI spine shows syrinx (expansion of the CSF space in the centre of the cord)
  • Syphilic pachymeningitis
    • Now very rare, untreated syphilis used to be much more common and can cause a patchy meningitis leading to poor function of the exiting nerve roots in the brainstem ad spinal cord
    • Test for EIA/VDRL serology
  • Motor neuropathy
    • Lead/heavy metal poisoning is the most common cause of a progressive motor neuropathy – check serum levels
    • Multifocal Motor Neuropathy is a rare inflammatory condition involving antibodies to nerve root antigen – check “anti ganglioside antibodies”; MMN has positive anti GM1 antibodies. Also nerve conduction will be different to MND – and show conduction block although this can be difficult to identify
  • Spinal muscular atrophies
    • Rare genetic disorders causing progressive muscle atrophy, of which there are a range that vary in severity, age of onset and rate if progression. Genetic tests available.
  • Kennedy’s Syndrome “Spinal and bulbar muscular atrophy”
    • X-linked condition, causing spinal and bulbar muscular atrophy. Only LMN pathology. Pathology is due to a mutation in the androgen receptor and therefore also has endocrine manifestations of androgen insensitivity.
    • Usually presents in young-middle aged adult males.
    • Ask about muscle cramps. Look for chin fasciculations and gynaecomastia


Now click here for how to diagnose and manage MND

Motor neurone disease for doctors and medical student exams

…  Or click here to learn how to diagnose and manage myasthenia gravis

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