Approach to weakness
Separate true weakness from fatigue, localise it from brain to muscle, spot the emergencies (cord compression, GBS, myasthenic crisis, tick and snake envenoming, periodic paralysis), and protect the airway.
Tier 1Approach to a presentation
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- First decide whether this is true weakness (loss of power) or fatigue, pain-limited movement, breathlessness or frailty. In general medicine, many "weak" patients aren't.
- Localise next: brain, cord, anterior horn cell, root, plexus, nerve, neuromuscular junction or muscle. The pattern plus reflexes and sensation usually decides it.
- Tempo matters. Minutes suggests vascular; hours to days suggests GBS, cord compression, myasthenic crisis, toxins or electrolytes; months suggests MND, myopathy or neuropathy.
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Sources
- Therapeutic Guidelines: NeurologyAU/NZTherapeutic Guidelines Limited
- Guillain-Barré syndrome: diagnosis and management, European Academy of Neurology and Peripheral Nerve Society guideline (van Doorn PA et al. Eur J Neurol 2023;30(12):3646-3674)EAN and PNS, 2023
- International consensus guidance for management of myasthenia gravis: 2020 update (Narayanaswami P et al. Neurology 2021;96(3):114-122)Neurology, 2020 (published 2021)
- Tick allergy (FAQ) (ASCIA information for patients and carers)AU/NZAustralasian Society of Clinical Immunology and Allergy (ASCIA)
- Snakebite in Australia: a practical approach to diagnosis and treatment (Isbister GK et al. Med J Aust 2013;199(11):763-768)Medical Journal of Australia, 2013
- The value of 'positive' clinical signs for weakness, sensory and gait disorders in conversion disorder: a systematic and narrative review (Daum C et al. J Neurol Neurosurg Psychiatry 2014;85(2):180-190)Journal of Neurology, Neurosurgery and Psychiatry, 2014
- Anticipating mechanical ventilation in Guillain-Barré syndrome (Lawn ND et al. Arch Neurol 2001;58(6):893-898)Archives of Neurology, 2001
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy