Stroke Misdiagnosis Claims: When a Delayed Diagnosis Causes Permanent Harm

What is stroke misdiagnosis?

Stroke misdiagnosis occurs when a clinician — in a GP surgery, A&E department, ambulance, or other healthcare setting — fails to identify that a patient is having a stroke, or attributes stroke symptoms to another cause. This results in a delay before the correct diagnosis is made and stroke treatment begins.

Stroke can also be misdiagnosed in the opposite direction: a patient may be incorrectly told they have had a stroke when their symptoms have another cause (a TIA, migraine with aura, Todd's paresis, or a functional neurological disorder). Misdiagnosis in either direction can cause harm.

The claims most commonly brought concern missed ischaemic stroke where the delay prevented thrombolysis or thrombectomy that would have reduced permanent neurological deficit.

The FAST criteria and clinical recognition standards

FAST (Face, Arms, Speech, Time) is a validated clinical screening tool used by NHS paramedics and clinicians to identify suspected stroke. A positive FAST screen requires immediate emergency response.

More detailed assessment tools — including ROSIER (Recognition of Stroke in the Emergency Room) — are used in A&E. A clinician who fails to perform a FAST assessment, fails to recognise a positive FAST screen, or provides a negative ROSIER assessment without considering the clinical picture in full may be below the required standard.

NICE stroke guideline NG128 specifies that all patients with suspected stroke should:

• Receive brain imaging (CT or MRI) immediately — within one hour of hospital arrival for patients eligible for thrombolysis
• Be assessed by a specialist stroke physician as soon as possible
• Be admitted to a stroke unit

Common scenarios in stroke misdiagnosis claims

A&E misdiagnosis as migraine or vertigo

A patient presents with sudden onset severe headache, facial droop, speech disturbance, or limb weakness. Symptoms are attributed to migraine, labyrinthitis or vertigo and the patient is discharged. They re-present with an established stroke.

GP failure to call 999

A GP arranges an urgent outpatient referral or waits to see whether symptoms resolve instead of calling 999. By the time the patient reaches hospital, the thrombolysis window has closed.

Ambulance failure to recognise stroke

A paramedic does not classify the patient as a stroke call. The patient is taken to the nearest hospital rather than the nearest stroke centre, causing further delay.

Failure to offer thrombolysis within the time window

The stroke is correctly identified but the treating team fails to assess eligibility for thrombolysis and deliver treatment within the four-and-a-half-hour window from symptom onset.

Failure to offer mechanical thrombectomy

A large vessel occlusion patient is not referred for mechanical thrombectomy within the extended window despite meeting eligibility criteria.

TIA mismanaged — stroke follows

A TIA is not recognised or properly investigated. Antiplatelet and (where indicated) anticoagulation therapy is not started, and the patient has a full stroke within days that prompt TIA management would have prevented.

What do you need to prove?

1. Duty of care — the clinician owed a duty to assess and treat you competently.
2. Breach of duty — the failure to diagnose stroke or treat it promptly fell below the standard of a reasonably competent clinician. Expert stroke neurology or emergency medicine evidence is required.
3. Causation — the delay caused additional neurological damage beyond what would have occurred with prompt treatment. Independent expert evidence is needed to establish what difference earlier treatment would have made.
4. Damage — permanent neurological deficit, disability, or financial loss resulted.

Causation in stroke misdiagnosis claims

Causation is central. It is not enough to show that stroke was missed — the claimant must show that earlier treatment would have produced a materially better neurological outcome.

For ischaemic stroke eligible for thrombolysis, published evidence supports substantial neurological benefit when treatment is delivered within the therapeutic window. Expert witnesses assess the likely extent of additional damage caused by the specific delay — drawing on evidence about infarct progression and published benefit data for thrombolysis and thrombectomy.

Where the patient was already outside the thrombolysis window when they first presented, or contraindications existed, causation may be more difficult to establish.

Compensation in stroke misdiagnosis claims

Compensation depends on the additional neurological deficit caused by the delay. A delay causing moderate additional disability may result in a six-figure award. Where the delay caused severe hemiplegia, aphasia, or total dependency, compensation including future care costs can exceed £1 million.

Time limit

Three years from the date of the stroke misdiagnosis or from the date of knowledge. Children have until age 21. Fatal cases: three years from date of death or date of knowledge.

Frequently asked questions

Related guides

• Medical negligence claims — complete guide
• A&E negligence claims
• Brain injury compensation claims
• Evidence for a medical negligence claim