Los Angeles Motor Scale (LAMS)
Stratifies stroke severity in the field.
When to Use
Use in a prehospital (i.e., by EMS providers) or triage setting for patients with stroke symptoms.
- The LAMS is a validated 3-item prehospital scoring tool derived from the motor exam components of the Los Angeles Prehospital Stroke Screen (LAPSS). It was designed to rapidly quantify stroke severity in the prehospital setting.
- LAMS ≥4 has a sensitivity of 81% and specificity of 89% for predicting large vessel occlusion (LVO).
- Although other scores such as the NIH Stroke Scale (NIHSS), Cincinnati Prehospital Stroke Scale (CPSS), Rapid Arterial oCclusion Evaluation (RACE) Scale, and the full Los Angeles Prehospital Stroke Screen (LAPSS) are more comprehensive, the LAMS is a much simpler assessment tool that takes only 20-30 seconds to complete, making it well-suited for prehospital or triage settings.
- Correlates strongly with the full NIHSS (gold standard) and predicts long-term functional outcomes following stroke events.
- Rapid access to time-sensitive interventions such as thrombolysis and endovascular therapy (EVT) for eligible patients is directly linked with improved long-term neurological outcomes for stroke patients.
- Early recognition of severe strokes (LAMS ≥4) by prehospital providers in the field shortens time to definitive diagnosis and treatment.
- Simple, reproducible, and rapid way to identify severe strokes in the prehospital setting.
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- For patients with suspected stroke and LAMS ≥4 (severe), potential LVO should be considered as the cause. Transportation to a Comprehensive Stroke Center, if available, should be coordinated as rapidly as possible to facilitate potential invasive treatments such as endovascular therapy (EVT).
- For patients with LAMS <4, acute stroke should still be considered. However, these patients are less likely to be LVO candidates for invasive treatment.
Baseline assessment and management should include:
- Vital signs (including point-of-care glucose).
- Determination of stroke symptom onset time (or time when the patient was last seen normal).
- Activation of stroke transportation protocol and/or stroke assessment team for rendezvous at Comprehensive Stroke Center (if available).
- Screen for contraindications to thrombolysis.
- Under appropriate circumstances and in consultation with both neurology and the patient, consider initiation of intravenous thrombolysis.
- Prioritize obtaining a stat non-contrast CT head to evaluate for hemorrhagic stroke when able. If negative for intracerebral hemorrhage (ICH), obtain a subsequent CT angiography (CTA) head and neck to evaluate for ischemic vascular occlusion.
- Consider other potential causes of neurologic deficits based on history, physical exam, and risk factors, including:
- Exacerbation of prior deficits.
- Complex migraine conditions.
- The LAMS is not a substitute for a full neurologic exam or NIHSS assessment by a stroke specialist. It is a screening tool to assist with transport and triage decisions in the prehospital environment.
- Regardless of the ultimate underlying diagnosis, neuroprotective supportive care should be employed to prevent progression of neurologic injury, including treatment of hypoglycemia, hypoxia, hypothermia, and/or hypotension.
- Blood pressure management is challenging in the prehospital phase without diagnostic imaging to confirm acute ischemic stroke vs. intracerebral hemorrhage (ICH) vs. other causes. Low blood pressure should be corrected empirically. High blood pressure should be managed per local protocol or in consultation with a neurologist.
- Whenever possible, patients with acute stroke should be transferred to a stroke center as soon as possible for full evaluation and treatment, as Comprehensive Stroke Centers have been shown to significantly improve clinical outcomes following stroke.
- Katie Lin, MD
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- Michael Hill, MD