Los Angeles Motor Scale (LAMS)

Learn the Los Angeles Motor Scale (LAMS): facial droop, 10-second arm drift, and grip on the affected side for a 0–5 prehospital motor stroke score. How to perform each item, common pitfalls, and how totals are used in triage alongside full stroke evaluation.

Los Angeles Motor Scale (LAMS)

Three-item motor screen (0–5) for acute stroke severity in the field. Rate the affected side after standard prompts (facial movement, 10-second arm hold, grip).

Facial droop *

0 — Absent: no facial asymmetry; normal on smile / show teeth / raise eyebrows / squeeze eyes shut.1 — Present: partial or complete lower facial droop.

Arm drift (10 s, palms down; ~45° if lying, ~90° if sitting) *

0 — Absent: no drift; holds against gravity.1 — Drifts down but does not reach the bed within 10 seconds.2 — Falls rapidly: cannot hold up; arm falls to the bed within 10 seconds.

Grip strength (patient grasps examiner's fingers) *

0 — Normal grip; no weakness.1 — Weak grip: some movement, reduced strength.2 — No grip: no meaningful movement (visible muscle contraction without movement scores here).

Los Angeles Motor Scale (LAMS) — criteria

Purpose

LAMS is a brief three-item motor scale (total 0–5) designed for prehospital characterization of acute stroke severity. It combines facial droop, arm drift against gravity, and grip strength on the affected side. In the derivation cohort, a total ≥4 was highly associated with persisting large arterial occlusion (see reference below).

Item definitions (published LAMS)

Domain	Pts	Description
Facial droop	0	Absent — no asymmetry; normal on smile, show teeth, raise eyebrows, squeeze eyes shut.
Facial droop	1	Present — partial or complete lower facial droop.
Arm drift	0	Absent — no drift; normal strength (10 s hold, palms down).
	1	Drifts down but does not reach the bed within 10 seconds.
	2	Falls rapidly — cannot hold against gravity; reaches the bed within 10 seconds.
Grip	0	Normal — no weakness (patient grasps examiner's fingers).
	1	Weak — some movement, reduced grip.
	2	No grip — no meaningful movement (visible contraction without movement maps here).

Positioning: elevate arms with palms down at approximately 45° if supine or 90° if sitting; count 10 seconds.

Total score

LAMS = facial + arm + grip, range 0–5. A cutoff ≥4 was reported as highly predictive of large artery occlusion in the original prehospital study; external validation and health-system performance vary—use as one input alongside time, examination, and imaging.

Reference

Lima FO, Silva GS, Nogueira RG, et al. A brief prehospital stroke severity scale identifies ischemic stroke patients harboring persisting large arterial occlusions. Stroke. 2008;39(8):2264-2267.

Limitations

Not a substitute for neuroimaging or stroke team decision-making.
Bilateral weakness, sensory-only syndromes, or posterior circulation strokes may not be captured well.
Inter-rater variability and protocol differences (positioning, timing) can change scores.

What is the Los Angeles Motor Scale?

The Los Angeles Motor Scale (LAMS) is a brief, structured neurological examination format used in the prehospital and early emergency setting for patients with suspected acute ischemic stroke. Rather than attempting to reproduce the full breadth of a comprehensive in-hospital stroke scale, LAMS focuses on three lateralized motor domains that can be assessed quickly at the bedside or in the field: face, arm against gravity, and hand grip.

The scale produces an integer total from 0 to 5 by summing item scores. Higher totals reflect more severe focal motor impairment on the affected side. In health systems that incorporate LAMS into protocols, the total score is often used as one triage signal among many—along with time last known well, stroke team activation rules, imaging availability, and institutional endovascular pathways.

Why use a short motor scale in stroke care?

Acute stroke care is highly time-dependent. Interventions such as intravenous thrombolysis and mechanical thrombectomy are most effective when delivered early, but treatment decisions require rapid risk stratification, severity estimation, and coordination of resources. Comprehensive scales can be informative yet time-consuming in moving environments (ambulance cabins, crowded emergency departments) or when staffing is limited.

A compact motor scale attempts to balance speed with signal: it emphasizes findings that are relatively easy to elicit, often visible within seconds, and clinically meaningful for hemispheric ischemia patterns that produce corticospinal tract dysfunction. LAMS is not a substitute for neuroimaging or specialist evaluation; it is a structured way to document severity and to support communication across EMS, triage nurses, and stroke teams.

Core principle: score the affected side

LAMS is intended to reflect the hemisphere-specific motor deficit associated with the acute event. In typical use, the examiner identifies the clinically affected side (or the side with the greater deficit if asymmetry is present) and assigns all three items with respect to that side. If findings are ambiguous—for example, subtle facial weakness, fatigue-related drift, or bilateral symptoms—clinical judgment and repeat examination may be necessary, and the score should be interpreted cautiously.

Posterior circulation strokes, sensory-predominant syndromes, isolated aphasia without weakness, or seizures with postictal paralysis may not present with a “classic” LAMS pattern. These situations highlight why LAMS should be embedded within a full acute stroke assessment rather than used in isolation.

How to test each LAMS domain

Facial droop (0 or 1 point)

The facial item detects lower motor neuron pattern weakness affecting the lower face, which commonly lateralizes with supratentorial ischemia when the corticobulbar pathways are involved. Testing should include prompts that activate both upper and lower facial musculature for comparison, such as asking the patient to smile, show teeth, raise eyebrows, and squeeze the eyes shut.

0 (absent): No meaningful facial asymmetry; movement appears symmetric and strength is normal for the prompts used.
1 (present): Partial or complete lower facial droop is observed. The key discriminator is clear asymmetry consistent with facial weakness rather than an alternative explanation (prior Bell palsy, structural asymmetry, cooperation issues).

Cooperation, language barriers, facial pain, dental prostheses, and prior neurologic deficits can confound interpretation. When feasible, repeat testing and corroborating findings (arm/grip) improve reliability.

Arm drift (0, 1, or 2 points)

The arm item measures the patient’s ability to maintain the paretic arm against gravity for a standardized interval. The patient holds both arms out with palms down. Positioning depends on whether the patient is lying or sitting:

Approximately 45 degrees of elevation if the patient is supine (or otherwise lying).
Approximately 90 degrees of elevation if the patient is sitting.

The examiner observes the affected arm for a 10-second count. The scoring emphasizes whether drift occurs and whether the arm falls completely within that window.

0 (absent): No drift; the arm is held steadily against gravity for the count.
1 (drifts down): The arm drifts downward but does not reach the supporting surface (bed, stretcher) within 10 seconds.
2 (falls rapidly): The arm cannot be maintained; it falls to the bed within 10 seconds.

Common pitfalls include testing duration shorter than 10 seconds, allowing the palm position to rotate into pronation/supination changes that alter apparent strength, supporting the arm unintentionally, and misattributing pain-limited movement to true paresis. Fatigue can worsen drift on repeat trials; consistency of technique across providers improves comparability.

Grip strength (0, 1, or 2 points)

The grip item assesses distal hand motor function by having the patient grasp the examiner’s fingers. The goal is a practical estimate of volitional flexor strength and coordination, recognizing that this is a coarse bedside maneuver rather than formal dynamometry.

0 (normal): Grip feels appropriately strong and symmetric relative to the unaffected side (or normal if bilateral testing is not applicable).
1 (weak grip): There is discernible grasping effort and some movement, but strength is clearly reduced.
2 (no grip): No meaningful grasp; in some formulations, visible muscle contraction without functional movement may still map to the severe category.

Arthritis, trauma, amputation, contractures, and intubation/sedation can limit testing. When grip cannot be assessed, document the limitation explicitly; forcing a numeric score in incompatible circumstances reduces clinical validity.

Calculating the LAMS total

The total score is the sum of the three items:

LAMS total = facial score + arm score + grip score

The theoretical range is 0 through 5 because facial weakness contributes up to 1 point while arm and grip each contribute up to 2 points. A total of 0 indicates no LAMS-defined motor abnormality across the three tested domains on the affected side, while 5 indicates severe abnormalities in all three.

Interpreting the total in triage workflows

In the original prehospital derivation context, higher LAMS totals—particularly totals of 4 or 5—were associated with a substantially increased likelihood of encountering a persisting large arterial occlusion among patients with acute ischemic stroke symptoms. Many EMS and hospital protocols therefore treat elevated LAMS totals as a prompt to prioritize:

Early notification of a stroke team or comprehensive stroke center
Expedited transport when routing decisions depend on severity
Readiness for emergent vessel imaging when clinically appropriate
Parallel preparation for time-sensitive reperfusion pathways where local criteria apply

It is essential to emphasize diagnostic nuance: a lower LAMS total does not exclude large vessel occlusion or severe stroke. Small distal occlusions, fluctuating exam findings, early presentation, collaterals, mixed syndromes, and measurement error can all produce lower scores despite significant pathology. Conversely, high scores are not specific to a single vascular lesion type; they indicate substantial motor impairment that should trigger standard acute stroke evaluation regardless of the underlying mechanism.

Comparison with broader stroke severity tools

Comprehensive scales such as the NIH Stroke Scale (NIHSS) integrate multiple domains beyond motor function—level of consciousness, language, neglect, visual fields, and more—making them well suited to detailed characterization in controlled settings. LAMS deliberately narrows the scope to three motor items to optimize feasibility in prehospital workflows.

In practice, teams may use LAMS for field triage communication and then obtain a fuller examination and imaging in hospital. The choice of which scale to document often depends on setting, training, protocol, and billing/documentation requirements rather than intrinsic superiority of one instrument in all contexts.

Quality assurance and operational considerations

Reliable LAMS use benefits from training that standardizes positioning, timing, and scoring anchors. Periodic audits (video review where available, paired examiner scoring, simulation drills) can reduce drift in how “weak grip” or “drift” is classified. Because stroke care is multidisciplinary, aligning language across EMS, nursing, and physicians reduces misunderstanding when a single integer score is relayed handoff-to-handoff.

Finally, LAMS should be applied within ethical and patient-safety constraints: protect airway and spine when positioning for arm testing, avoid maneuvers that exacerbate injury, and adapt examination technique for pediatric, pregnant, or critically ill populations according to local guidance.