Limb Weakness Station

Author – Dr Karthikeyan Sivaganesh  Editor Dr James Mackintosh

Last updated 06/05/24

Table of Contents

How to Use


  1. Read the brief below (1 minute). 
  2. Take a history (6 minute).
  3. Answer viva questions (3 minute).


  1. Familiarise yourself with the history & examination findings 
  2. After completing the history, viva the candidate

Candidate Brief

Mr Chen is a 64-year-old man who has presented to the GP with difficulty walking. Please take a history, examine the patient and discuss appropriate management options.

Presenting Complaint

  • You are worried as you have been tripping involuntarily while walking your dog.

History of Presenting Complaint

  • Site: Difficulty lifting both legs on walking but predominantly on the left. Wife feels that you lift your legs much higher than usual when walking

  • Onset: First tripped 3 months ago. 

  • Character: Legs feel weak and heavy

  • Timing: Last week tripped 3 times on different days. It has worsened since onset (Student must specifically ask if symptoms have worsened).

  • Associated features: No sensory changes (only if specifically asked), no joint pain, no pain in legs or back. Sometimes, have difficulty holding the cup of tea and once dropped it accidentally.

  • Exacerbating/Relieving factors: No provoking factors. Tripping happens unexpectedly. You sit more often, but this does not help.

Systems Review

  • Neurological: apart from leg weakness, no other neurological deficits
  • GI: No change in bladder or bowel function
  • Otherwise well, no other problems
  • Red flags: as below
    • Trousers feel looser around the calf and thigh.
    • Feel more tired recently but no night sweats, change in appetite, fevers or recent infection

Previous Medical History

  • Well controlled Asthma
  • No known hospital admissions or recent surgeries

Drug History

  • Blue Salbutamol inhaler PRN


  • NKDA

Social History

  • Stopped smoking 5 years ago - smoked 5 a day for 20 years (only if asked).
  • Drink alcohol on social occasions only.
  • Never taken recreational drugs.
  • Works as a chef at a renowned restaurant.
  • Live with your wife with no problems at home.

Family History

  • Father has Parkinson's Disease
  • Mother has Breast Cancer


  • Ideas: Thinks this might be Parkinson’s disease
  • Concerns: Worried about Parkinson’s and if symptoms will impact your ability to work
  • Expectations: Want to know the diagnosis and if you should do anything to improve the symptoms.


  • HR: 76 bpm
  • BP: 126/84 mmHg
  • SpO2: 98%
  • Temperature: 36.6℃
  • Respiratory Rate: 14 breaths per min

Neurological Examination

  • Upper limbs
    • Mild atrophy of thenar eminence. 
    • Normal tone. 
    • Normal power on all joint movements. 
    • Reflexes normal. 
    • Pin-prick, vibration and proprioception sensation normal.
  • Lower limbs: 
    • Prominent atrophy of tibialis anterior in the left leg compared to the right. Fasiculations are seen bilaterally.
    • Reduced tone bilaterally.
    • Reduced power on dorsiflexion of both feet but prominent on the left. Reduced power on hip flexion bilaterally but normal power in other joint movements.
    • Increased reflexes on tapping the patellar and Achilles tendon. Babinski's sign is negative bilaterally.
    • Pin-prick, vibration and proprioception sensation normal.

1. What is the most likely diagnosis and explain why?

  • Motor neuron disease (MND) - a mix of upper and lower motor neuron signs in the absence of sensory deficits is characteristic of MND. A bilateral foot drop suggests a systemic problem rather than a local one. Patients often present with involuntary tripping or difficulty holding objects due to reduced muscle strength

2. What are the types of MND?

  • Amyotrophic Lateral Sclerosis (ALS is the commonest type). Subtypes include:
    • Spinal ALS → classic MND
    • Bulbar ALS → Tongue, muscles involved in chewing and swallowing are affected causing difficulty talking, chewing and swallowing
  • Progressive Muscular Atrophy – Only lower motor neuron signs. Distal muscles affected before proximal muscles
  • Primary Lateral Sclerosis – Only upper motor neuron signs

3. What blood tests would you consider doing in primary care?

  • Bloods:
    • Vitamin B12, Folate - to exclude subacute combined degeneration (although unlikely as there are no sensory deficits, it can cause both upper and lower motor neuron signs)
    • FBC and Iron studies - assess for microcytic anaemia, which can cause tiredness. If iron deficient, consider bowel cancer due to patient’s age
    • Thyroid Function Tests - hypothyroidism can cause tiredness

4. Given the suspected diagnosis of MND, how would you manage this patient in primary care?

  • Urgent referral to neurologist informing about a suspected diagnosis of MND (as per NICE guidance).
  • Provide the patient with a leaflet about the diagnosis and direct them to local support groups or national charities that can help them through their diagnosis.
  • Discuss legal rights, including social care support, occupational therapy input, physiotherapy, employment rights and benefits.
  • Notify the Driver and Vehicle Licensing Agency (DVLA).
  • Opportunities for advance care planning e.g. LPA

5. What treatment may be provided in secondary care?

  • Riluzole
    • Glutamate receptor antagonist
    • Prolongs life by about 3 months
  • Respiratory care – Use BIPAP (non-invasive ventilation) at night
  • Nutrition support – Percutaneous endoscopic gastrostomy tube (PEG) is preferred due to impaired swallow
  • Prognosis is poor: 50% of patients die within 3 years of diagnosis
  1. Dr Colin Tidy. Motor Neurone Disease [Internet]. 2015. Available from: [Accessed 24/3/24]
  2. [Accessed 31/3/24]

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