Reasoning GP · Algorithm · 1-page summary
Sensory neuropathy in adults
For: adults with numbness, tingling or burning pain suggesting a peripheral neuropathy, in primary care. Not for: children, or sudden focal deficits (stroke → 999). Drug titration and detail → the full algorithm.
Core rule: time course and pattern first. Months to years, symmetrical, sensory, feet first = outpatient screen. Days to weeks, any weakness, asymmetry or brisk reflexes = a different disease with a different urgency.
0Stop — call 999 now — any one feature is enough
- Rapidly ascending weakness + sensory loss over days to a few weeks, reduced or absent reflexes, autonomic swings (Guillain-Barré); or breathlessness, weak cough, difficulty swallowing or speaking → 999
- Sensory level, bilateral leg numbness or weakness, saddle anaesthesia, bladder or bowel disturbance, brisk reflexes or upgoing plantars (cord, cauda equina, transverse myelitis) → 999 emergency MRI spine.
- Facial numbness with facial weakness, dysarthria, diplopia, dysphagia, visual symptoms or limb weakness → 999 stroke assessment.
- Do not arrange outpatient nerve studies for suspected Guillain-Barré: it needs same-day admission.
1Triage by tempo and pattern
| Pattern | Think → action |
|---|---|
| Acute (≤4 weeks) | Guillain-Barré, vasculitis, toxic → blocks 0 and 2 |
| Subacute, motor | Weeks to months, motor (CIDP >8 weeks) → Urgent neurology |
| Asymmetric, patchy | Mononeuritis multiplex = vasculitis → block 2 |
| Brisk reflexes, UMN | Central lesion → urgent MRI spine + neurology; cord signs → 999 |
| Chronic, distal | Symmetrical, sensory → first-line screen → Routine |
2Screen — one row is enough
- Vasculitic (mononeuritis multiplex, purpura, known RA/SLE/Sjögren's): rapidly progressive + systemic illness → Same-day admission; severe pain, weakness or systemic → Same-day neurology + rheumatology advice; otherwise Urgent. ANCA, ANA, ENA, complement, CRP, urine dip.
- Foot ulcer + fever, sepsis, ischaemia, deep or bone infection, gangrene → Acute services now. Other active foot problem, incl. warm swollen (Charcot) foot → Foot service ≤1 working day, offloaded.
- B12 deficiency + posterior column signs (subacute combined degeneration) → B12 now + Urgent neurology advice
- Aged ≥60 + persistent bone or back pain, or unexplained fracture → offer FBC, calcium, ESR or PV, SPEP + free light chains; suggests myeloma → Suspected cancer pathway
- Rapidly progressive + weight loss, smoking, nodes or cancer → Urgent neurology + NG12 route for the primary.
3Assess — once blocks 0–2 are answered
☐ Vibration (128 Hz), joint position, pinprick map, temperature ☐ 10 g monofilament ☐ Power, reflexes, plantars, Romberg, gait ☐ Feet, pulses, postural BP
☐ Together: FBC, ESR/CRP, U&E/eGFR, LFT, HbA1c, B12 ± folate, TSH, SPEP + immunoglobulins, urine dip ☐ AUDIT-C; all drugs incl. B6 supplements. Not in primary care: nerve studies (via neurology), skin biopsy, MRI brain without UMN or cranial signs.
4Classify — causes often coexist
- Diabetes or impaired glucose tolerance — commonest; HbA1c 42–47 counts; OGTT if normal but suspicion persists.
- B12 — total <180 ng/L deficient; 180–350 indeterminate → consider MMA/homocysteine. Neurological features → treat now.
- Alcohol or drugs — AUDIT-C; long-term nitrofurantoin, metronidazole, isoniazid, amiodarone, chemotherapy, excess B6.
- Paraprotein — on SPEP → Prompt haematology. Thyroid, CKD, coeliac — treat the cause.
- Uncertain — idiopathic only once the full screen is negative: say so; don't re-investigate a stable picture.
5Treat today — the cause first
- B12 + neurological features: hydroxocobalamin 1 mg IM alternate days until no further improvement, then every 2 months. Alcohol: reduction + thiamine. Nitrofurantoin: review within the UTI plan.
- Painful neuropathy (none for painless numbness): CG173 choice of amitriptyline, duloxetine, gabapentin, pregabalin; local order amitriptyline → gabapentinoid → duloxetine. One drug; switch, don't combine.
- Gabapentinoids (Schedule 3): renal function first, start low if frail. Duloxetine not if CrCl <30. Tramadol rescue only; no strong opioids. Driving advice. Doses: NICE/SPC, BNF, local formulary.
- Feet: daily checks; no barefoot walking, hot water bottles or self-cut callus.
6Refer routinely — and review
- Unexplained after full screen, suspected CMT, refractory pain → Routine neurology
- Diabetes: moderate foot risk → foot protection ≤6–8 weeks; high risk ≤2–4 weeks. Non-diabetic protective-sensation loss → podiatry.
- Review 2 weeks after a drug change; judge efficacy at 4–6 weeks at an adequate dose; recheck the cause at 3 months.
7Never reassure by
- Normal examination or nerve studies when the pain burns (small fibre).
- A normal SPEP (light-chain disease and amyloid are missed).
- A painless warm, swollen foot (Charcot).
- No pain in a numb foot: the monofilament, not the pain score, sets ulcer risk.
- A borderline B12 with neurological signs: treat, don't repeat.
- The first cause found: diabetes, alcohol and drugs often coexist.
8Safety-net — say it, then document it
999 “Call 999 if your legs become weak, weakness or numbness spreads up your body over hours or days, you have trouble breathing or swallowing, numbness between your legs or around your bottom, or new bladder or bowel problems.” Same day “Contact us the same day if any weakness develops, the numbness climbs up your legs, or you become unsteady quickly. Any break in the skin, blister, colour change or new swelling on the foot — the same day if you have diabetes. A warm, red, swollen foot, even without pain — the same day.”
✓Safe to leave primary care only if — all five, documented
No block 0–2 feature
Time course, distribution, power, reflexes and plantars recorded
Full first-line screen sent, incl. SPEP and urine dip
Monofilament and foot risk recorded; foot advice given
Drug review dated; driving advice and safety-net given
Summary of the full Reasoning GP sensory neuropathy algorithm, which holds the detail, examination, investigations and evidence. Sources: NICE CG173, NG19, NG239, NG12 (updated April 2026), NG28, PH38; local neuropathic pain guideline; MHRA. Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.