Imaging recommendation · Neuro · Head & Neck

Focal neurologic weakness / new deficit — imaging triage

Q: What's the alternative imaging for focal neurologic weakness / new deficit — imaging triage when acute focal weakness — stroke?

CT — Stroke protocol (see stroke-acute) (iv contrast).

Q: What's the alternative imaging for focal neurologic weakness / new deficit — imaging triage when cord compression suspected (sensory level, bladder)?

MRI — MRI total spine (see cord-compression, cauda-equina-emergent) (iv contrast).

Q: What's the alternative imaging for focal neurologic weakness / new deficit — imaging triage when subacute / chronic — ms / demyelinating?

MRI — MRI brain + spine with contrast (see ms-workup, adem) (iv contrast).

Q: What's the alternative imaging for focal neurologic weakness / new deficit — imaging triage when peripheral / radicular pattern?

MRI — MRI of relevant level (see lumbar-radic, cervical-radic) (no contrast).

Q: What's the alternative imaging for focal neurologic weakness / new deficit — imaging triage when suspected nmj (myasthenia, lems) — thymoma screen?

CT — CT chest (see mediastinal-mass) (iv contrast).

Recommended: Stroke protocol if acute; targeted MRI if subacute/chronic is the preferred imaging study for focal neurologic weakness / new deficit — imaging triage. Acute onset (< 24 h) — treat as stroke until proven otherwise: CT head non-contrast + CTA head/neck ± CT perfusion.

Recommended study

Stroke protocol if acute; targeted MRI if subacute/chronic

CT IV contrast Preferred Neuro · Head & Neck EmergencyAcute inpatientOutpatient Reviewed 2026-05

Acute onset (< 24 h) — treat as stroke until proven otherwise: CT head non-contrast + CTA head/neck ± CT perfusion. Subacute weakness — MRI brain ± cervical/thoracic spine depending on level. Pure lower-extremity weakness with sensory level or bladder symptoms — emergent MRI total spine for cord compression.

If the default doesn't apply

Acute focal weakness — stroke

CT Stroke protocol (see stroke-acute) IV contrast

Cord compression suspected (sensory level, bladder)

MRI MRI total spine (see cord-compression, cauda-equina-emergent) IV contrast

Subacute / chronic — MS / demyelinating

MRI MRI brain + spine with contrast (see ms-workup, adem) IV contrast

Peripheral / radicular pattern

MRI MRI of relevant level (see lumbar-radic, cervical-radic) No contrast

Suspected NMJ (myasthenia, LEMS) — thymoma screen

CT CT chest (see mediastinal-mass) IV contrast

Watch-outs

Cord compression is time-sensitive

Sensory level + leg weakness + bladder/bowel = emergent MRI spine, do not wait for outpatient.

Stroke mimics on plain CT

Hypoglycemia, post-ictal Todd's paralysis, migraine aura all mimic stroke — CT is for exclusion of bleed, not confirmation of infarct.

Pearls

DWI is positive within minutes of infarction — MRI catches what CT misses in the first 24 h.
Bilateral leg weakness + back pain + saddle anesthesia = cauda equina until imaging proves otherwise.
Anti-AChR myasthenia gravis: CT chest is mandatory at diagnosis to exclude thymoma.