Strokes can present differently in different people. Generally they are divided into anterior, posterior, and hemorrhagic varieties. In the prehospital environment we cannot correct the underlying problem, so we need to be able to identify a stroke and determine the appropriate facility to transport to. Where I work we have a designated stroke centre that can be reached within approximately 50 minutes from the furthest point of our coverage area. There are several other hospitals that may be closer, however none of them have the ability to perform endovascular therapy. Many services have similar circumstances. In order to ensure that the stroke centre is not overburdened by inappropriate patients, several stroke scales and assessments have been developed. Most, if not all, services in North America use some variation of the FAST stroke assessment, and many use an additional severity scale to determine destination. IN Ontario Canada (where I work) we use the Los Angeles Motor Scale to determine the likelihood of large vessel occlusion. These are stroke patients who will benefit significantly from EVT, provided they are within the acceptable time-frame from onset to treatment, and they are not contra-indicated. Patients who do not meet criteria can typically be managed with thrombolytic therapy, potentially at a local ED.
Stroke assessment: The FAST exam
FAST stands for FACE, ARMS, SPEECH, and TIME. This means we want to assess these patients for facial symmetry, pupil equality, and eye movement. As the cranial nerves do not cross over like the nerves below the neck, any abnormality will occur on the side where the lesion is. ARMS, refers to testing of bilateral grip strength, pedal strength, and assessing for pronator drift. Speech should be assessed for slurring, inappropriate responses, or absence of responses. TIME is probably the most critical factor. We need to know when the symptoms began EXACTLY, or when the person was last seen normal. This matters because stroke centres will only provide certain interventions within a defined time period. Where I work, treatment must be available within 6 hours of symptom onset.
I won't cover the different presentations between ischemic, hemorrhagic, anterior, and posterior CVA here, as that was done in an earlier post (Neurological emergencies).
The LAMS:
The Los Angeles Motor Scale assesses 3 criteria in order to determine the probability of large vessel occlusion. It assesses the following:
Facial Droop: 0 points if absent, 1 point if present.
Arm Drift: 0 points if absent, 1 point if drifts slowly, 2 points if falls rapidly.
Grip Strength: 0 points if normal, 1 point if weak grip, 2 points if grip is absent.
0-3 points indicates a minor risk of large vessel occlusion, and a score of 4 or higher indicates major risk.
The LAMS is important as an initial assessment tool because it can be reported to the interventionalist enroute, allowing them to begin planning care for your patient.
As with any patient, your primary assessment should be utilized to correct life threats, particularly those involving the airway. Your stroke assessment and LAMS can occur concurrently during your secondary physical assessment, and really only take 30 seconds to 1 minute to complete. The biggest thing with stroke patients is to get an accurate time of onset, and identify risk factors. A word of caution though, there is a major stroke mimic that needs to be ruled out: HYPOGLYCEMIA. You should be checking a blood sugar ASAP on these patients to ensure that what you are seeing truly is a stroke.
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