Suspected Stroke – Diagnosis (Tests, Scans) and Assessment
A stroke, or cerebrovascular accident (CVA) is the neurological dysfunction that arises when there is an interruption of the blood supply to a specific region of the brain. Stroke causes sudden death of brain cells due to lack of oxygen. It is a major life-threatening emergency and recognizing the early signs and symptoms of stroke is very important for identification of possible stroke patients. Early diagnosis and intervention are crucial for minimizing brain injury and maximizing the patient’s recovery.
The 7 D’s of Stroke Care for Diagnosis and Treatment of Stroke
These are the key points in management of stroke patients known as the 7 D’s of stroke care as described by the American Heart Association. The 7 D’s are :
- Detection of the onset of signs and symptoms
- Dispatch of EMS
- Door of the emergency department
- Drug administration
Detection of the onset of signs and symptoms of stroke
Most first-time or repeat strokes occur at home. Therefore educating the community at large, and stroke patients and their families in particular, regarding early recognition of the signs and symptoms of a stroke can help a patient to be diagnosed and treated in time so as to obtain maximum recovery.
The onset of stroke symptoms may be insidious or the signs and symptoms may come on suddenly, such as
- Sudden severe headache without any known cause.
- Sudden numbness, weakness, or paralysis of the face, arm, or leg, especially on one side of the body.
- Sudden confusion.
- Difficulty with speaking or understanding.
- Trouble seeing in one or both eyes.
- Dizziness, loss of balance and coordination, and difficulty in walking.
Dispatch of EMS
Educating stroke patients and their families to activate the emergency medical service (EMS) system, by calling 911 or the emergency response number, as soon as they recognize the signs and symptoms of stroke is a very important step in stroke care.
EMS personnel can identify and transport the patient, with pre-arrival notification, to a hospital which can provide acute stroke care. Pre-arrival notification prepares the hospital to receive the patient and start evaluation and management efficiently.
Door of the ED
From arrival of the patient to urgent assessment in the ED. General assessment of the patient by the emergency doctor should be complete within 10 minutes and an urgent noncontrast CT scan ordered.
This includes history, neurological assessment, and diagnostic tests, including a CT scan done within 25 minutes of arrival, and interpretation of the scan within 45 minutes of arrival.
Decision regarding treatment, including fibrinolytics, is taken.
The final step is appropriate drug administration and post-administration monitoring. The initiation of fibrinolytic therapy in patients without contraindications should ideally be done within 1 hour of hospital arrival and 3 hours from onset of symptoms so as to get the best results of therapy.
Stroke Assessment Tools
There are two common neurological evaluation tools that may be used by paramedics and other medical personnel to recognize stroke in the out-of-hospital setting. These are the :
- Cincinnati Prehospital Stroke Scale (CPSS)
- Los Angeles Prehospital Stroke Screen (LAPSS)
Cincinnati Prehospital Stroke Scale (CPSS)
The CPSS identifies stroke on the basis of 3 physical findings
- Facial droop. The patient is asked to smile or show teeth. Normally, both sides of the face move equally. In stroke patients, one side of the face will not move as well as the other.
- Arm drift. The patient is asked to close eyes and extend both arms straight out, with palms up, for 10 seconds. Normally, both arms move the same or both arms do not move at all. In stroke patients, one arm does not move or one arm drifts down compared with the other.
- Abnormal speech. The patient is asked to say “You can’t teach an old dog new tricks”. Normally, the patient uses correct words with no slurring. Slurred speech, the use of wrong words or the inability to speak is noted in a stroke patient.
It hardly takes a minute to evaluate the patient using the CPSS. One abnormal finding indicates 72% probability of stroke, while the presence of 3 abnormal findings indicates over 85% probability of a stroke.
Los Angeles Prehospital Stroke Screen (LAPSS)
The LAPSS is a more detailed evaluation for acute stroke. The criteria are as follows and are to be answered as “yes” or “no”.
- Age >45 years
- History of seizures or epilepsy absent
- Symptom duration <24 hours
- At baseline, patient is not wheelchair bound or bedridden
- Blood glucose between 60 and 400
- Obvious asymmetry (right vs left) in any of the following 3 examination categories (must be unilateral) – facial smile/grimace, grip, and arm strength.
A person having positive findings on all 6 criteria has a 97% probability of an acute stroke.
Diagnosis of a Stroke
- History. Taking a detailed history is very important and family members or other close contacts can help if the patient is unable to communicate. History of previous TIA’s (transient ischemic attack) is highly probable that a patient with the relevant symptoms has a stroke. It may also suggest the cause of stroke by noting any risk factors such as atrial fibrillation, diabetes mellitus, hypertension (high blood pressure), or use of drugs such as warfarin. Determining the time of onset of symptoms is the important criteria for starting fibrinolytic treatment, where indicated. If the patient wakes from sleep with symptoms of stroke, the onset time may be taken as the last time the patient was seen to be normal.
- A thorough physical examination.
- Neurological examination to uncover deficiencies in brain function
Tests and Scans
Tests that are normally done for diagnosis, as well as to determine the type of stroke, the site of blockage or hemorrhage, and the cause of stroke include :
- CT scan of the brain should be done as soon as possible in a suspected stroke patient. An emergency CT scan should ideally be done within 25 minutes of arrival of the patient at a stroke center and the results interpreted within 45 minutes of arrival. This will identify the type of stroke by highlighting the site of blockage or hemorrhage. Specific stroke treatment will depend upon this finding.
- MRI of the brain may be done instead of a CT scan or it may be done later.
- Cerebral angiography is an invasive procedure which may be used for patients with a TIA who need surgery. It may also detect an aneurysm.
- Magnetic resonance angiography (MRA) or CT angiography are non-invasive methods of evaluating the carotid arteries and arteries in the brain to look for abnormal blood vessels that could be the cause of stroke.
- Echocardiogram is useful when it is suspected that a blood clot from the heart (embolus) could have caused the stroke.
- Electrocardiogram (ECG) and Holter monitoring of the heart rhythm is used to detect atrial fibrillation (a type of irregular heart beat) could be the cause. Atrial fibrillation is one of the most important causes of stroke, where a blood clot may get dislodged from the heart and travel up to the brain to cause occlusion of an artery in the brain.
- Carotid duplex is an ultrasound procedure done to assess blood flow through the carotid artery to the brain. This can identify narrowing of the carotid arteries in the neck (carotid stenosis), which may have caused the stroke.
- Blood tests may include a complete blood count (CBC), bleeding time, and blood clotting tests such as prothrombin time or partial thromboplastin time. Blood sugar, lipid profile, and blood cholesterol should also be monitored.
- Cerebrospinal fluid (CSF) examination is possible by doing a spinal tap (lumbar puncture) when there is suspicion of a hemorrhagic stroke but the CT scan does not clearly indicate bleeding.