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Surgical sieve
🧓 Off legs
Is this WEAKNESS you can demonstrate, or an inability to stand with normal power? "Off legs" and "acopia" are not diagnoses — there is nearly always one, and it is usually findable in an hour.
| Spinal cord compression Must exclude | Bilateral leg weakness with a sensory level, brisk reflexes and upgoing plantars, usually with back pain that came first. Known malignancy makes it the working diagnosis.Dexamethasone and whole-spine MRI. Examine the reflexes and the plantars in every off-legs patient — it takes a minute. |
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| Cauda equina syndrome Must exclude | Bilateral leg weakness with saddle anaesthesia and bladder change. Retention with overflow gets charted as incontinence.Ask about the bladder and examine the perineum. Emergency MRI. |
| Sepsis (any source) Must exclude | In the frail and the elderly, "off legs" is one of the commonest presentations of infection — before the fever, and often instead of it.A full set of observations and a septic screen in everyone. Do not accept "off legs" without looking for a cause. |
| Stroke Must exclude | Asymmetry is the clue — one leg weaker than the other, a facial droop, or new speech disturbance. A lacunar stroke can present purely as a weak leg.Glucose first, then urgent CT and a stroke call. Establish when they were last known well. |
| NOF fracture Must exclude | An UNDIAGNOSED hip fracture, in a patient who cannot say what happened. A shortened externally rotated leg — but an impacted fracture looks normal and still cannot weight-bear.X-ray the hip where there is a fall, hip or groin pain, or clinical suspicion — pain on axial loading or rotation is enough to image. If suspicion persists despite a normal X-ray, MRI is the preferred next test. |
| Hypoglycaemia Must exclude | Can present as focal weakness that mimics a stroke exactly, and it resolves in minutes with treatment.A capillary glucose before the CT scanner. Every time. |
| Guillain-Barré syndrome Must exclude | ASCENDING symmetrical weakness with ABSENT reflexes, over days, often two to four weeks after a diarrhoeal or respiratory illness. Sensory symptoms are mild relative to the weakness.Serial FORCED VITAL CAPACITY, not saturations — respiratory failure arrives with normal oxygen right up to the end. Neurology urgently. |
| Electrolyte derangement Time-sensitive | Sodium, potassium, calcium and magnesium all cause weakness. Severe hypokalaemia and hypercalcaemia are the ones that present as not being able to get up.U&E, bone profile and magnesium in everyone. One of the few reversible-in-a-day causes. |
| Parkinson's medication delay Time-sensitive | A Parkinson's patient whose levodopa was late, missed, or stopped because they were nil by mouth. Rigidity and immobility within hours; at the extreme, parkinsonism-hyperpyrexia.Give the doses AT THE PATIENT'S OWN PRESCRIBED TIMES, aiming within 30 minutes — this is a time-critical medicine. Use a patch conversion if they cannot swallow. |
| Delirium Time-sensitive | Acute fluctuating inattention. Hypoactive delirium looks exactly like "gone off their legs" and is the form that gets missed.4AT, then find the cause — infection, drugs, retention, constipation, pain, hypoxia. |
| Urinary retention Time-sensitive | A painfully full bladder stops people standing, and in the confused or frail it is never volunteered. Also a cause of delirium and of a rising creatinine.A bladder scan is thirty seconds and is worth doing in every off-legs patient. |
| Anaemia Time-sensitive | Progressive exertional weakness and dizziness. A slow GI bleed presents this way long before it presents as melaena.FBC, and then a cause. New anaemia in an older person is a reason to look, not just to transfuse. |
| Drug toxicity or withdrawal Time-sensitive | Sedatives, opioids, antihypertensives and anticholinergics — and a recent dose change matters more than a long-standing prescription. Four or more medicines is itself a risk factor.Read the chart as a cause, not as background. Ask specifically what changed in the last fortnight. |
| Myasthenia gravis Time-sensitive | FATIGABLE weakness — worse with repetition and at the end of the day — with ptosis, diplopia or bulbar symptoms. A crisis can be precipitated by infection or by a new drug.Forced vital capacity again, not saturations. Check the drug chart against the list of medicines that precipitate crisis. |
| Peripheral neuropathy / poor mobility Common | The background most "off legs" happens against: neuropathy, deconditioning, arthritis, poor vision, poor footwear, and a home that has become unmanageable.Usually several small causes at once rather than one big one — but only after the reversible ones above have been excluded, not instead of excluding them. |
15 differentials · 11 open a full pathway in the app.