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This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
Key points
- Unilateral sudden numbness is stroke/TIA until proven otherwise.
- Bilateral sensory level, gait change or bladder symptoms localises to spinal cord.
- Stocking-glove sensory loss suggests peripheral polyneuropathy, commonly diabetes, alcohol, B12 deficiency, renal disease or medications.
- Dermatomal symptoms with back/neck pain suggest radiculopathy; hand distribution can be median, ulnar or radial entrapment.
- Investigations should be guided by localisation rather than a broad untargeted panel.
Approach to the Presentation
Map distribution: face/arm/leg cortical, crossed face-body brainstem, sensory level cord, dermatomal root, stocking-glove neuropathy or single nerve entrapment. Ask about weakness, gait, sphincters, pain, diabetes, alcohol, B12 risk, chemotherapy, HIV and autoimmune symptoms.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Stroke/TIA | must-not-miss | Sudden unilateral numbness, face-arm-leg pattern, aphasia/visual symptoms or weakness | CT/CTA stroke pathway |
| Spinal cord compression/myelitis | must-not-miss | Bilateral symptoms, sensory level, gait disturbance, bladder/bowel dysfunction | Urgent MRI spine |
| Cauda equina syndrome | must-not-miss | Saddle anaesthesia, urinary retention, bilateral sciatica, leg weakness | Urgent MRI lumbosacral spine |
| Diabetic polyneuropathy | common | Length-dependent burning/numbness feet, reduced vibration/ankle reflexes | A1c, monofilament/vibration testing |
| B12 deficiency neuropathy/myelopathy | common | Paraesthesias, sensory ataxia, cognitive/mood symptoms, macrocytosis; vegan/pernicious anaemia/metformin/PPI risk | B12, CBC, MMA if equivocal |
| Radiculopathy | common | Dermatomal pain/numbness, reflex or myotomal change, worse with spine movement | Clinical; MRI if red flags or persistent/progressive deficit |
| Carpal tunnel/ulnar neuropathy | common | Median or ulnar distribution symptoms, nocturnal hand symptoms or elbow-related symptoms | Provocative tests; NCS if unclear/severe |
| Anxiety/hyperventilation | common | Perioral and bilateral hand tingling with panic symptoms | Clinical after excluding red flags |
| Multiple sclerosis relapse | less common | Subacute sensory symptoms in young adult, optic neuritis, diplopia, Lhermitte phenomenon | MRI brain/spine with contrast; CSF oligoclonal bands |
| Medication/toxin neuropathy | less common | Chemotherapy, isoniazid, metronidazole, alcohol, nitrofurantoin, excess B6 | Medication/toxin history |
Red Flags & Key History
Symptoms
Sudden onset focal sensory loss
Saddle anaesthesia or urinary retention
Sensory level or progressive gait impairment
Numbness with weakness or cranial nerve findings
Length-dependent chronic burning feet
Signs
Objective sensory level
Upper motor neuron signs
Loss of ankle reflexes with stocking sensory loss
Thenar wasting or intrinsic hand weakness
Approach to Investigation
First-line
Neurological localisation examPinprick, light touch, vibration, proprioception, reflexes, power and gait.
Glucose/A1c, B12, TSH, CBC, creatinineCommon reversible neuropathy contributors.
CT/CTA if acute focal deficitStroke pathway for sudden unilateral symptoms.
Second-line
MRI spineSensory level, myelopathy, cauda equina or progressive neurological deficit.
NCS/EMGEntrapment neuropathy, polyneuropathy or radiculopathy localization.
MRI brain/spine + CSFSuspected demyelination.
Specialist
NeurologyAcute focal, progressive, multifocal or unexplained objective sensory syndromes.
Management Principles
MCC Weakness objective + Canadian neurological localisation approach1
Emergency patterns
- Stroke pathway for sudden focal sensory loss
- Urgent MRI and surgical/neuro consultation for cord or cauda equina features
2
Peripheral neuropathy
- Treat cause: glycaemic control, B12 replacement, alcohol reduction, medication change
- Foot care, falls prevention and neuropathic pain management if painful
3
Entrapment/radiculopathy
- Splinting/activity modification or physiotherapy first when mild
- Image/refer for progressive weakness, myelopathy or refractory severe symptoms
Complications & Pitfalls
- Ignoring distribution: localisation determines the test.
- Missing cauda equina: saddle sensory change or retention needs urgent MRI.
- Attributing sudden unilateral numbness to anxiety: stroke/TIA must be considered.
- Forgetting B12: it is reversible and can cause neuropathy plus myelopathy.
MCCQE1 Exam Tips
- 1Sudden unilateral numbness = stroke/TIA workup.
- 2Stocking-glove = polyneuropathy; start with diabetes, B12, renal, alcohol and drugs.
- 3Sensory level = cord until proven otherwise.
- 4Saddle anaesthesia + urinary retention = cauda equina.
- 5Carpal tunnel affects thumb, index, middle and radial ring finger; ulnar neuropathy affects fifth finger.
- 6Hyperventilation causes perioral and bilateral hand tingling.
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