Posterior Circulation, Brainstem, and Cerebellar Syndromes
Key Takeaways
- Posterior circulation strokes can be missed because dizziness, nausea, visual symptoms, and gait instability may look less dramatic than hemiplegia or aphasia.
- Brainstem strokes often produce crossed findings, cranial nerve deficits, dysphagia, dysarthria, diplopia, or respiratory compromise.
- Basilar artery occlusion is a neurologic emergency that may progress to quadriplegia, coma, or locked-in syndrome.
- Cerebellar infarction or hemorrhage can worsen from edema and obstructive hydrocephalus even when early limb strength is preserved.
- SCRN nursing judgment prioritizes airway, swallow safety, aspiration prevention, fall prevention, and rapid escalation for declining consciousness.
The subtle stroke problem
Posterior circulation supplies the brainstem, cerebellum, occipital lobes, thalami, and parts of the temporal lobes. These strokes are tested because they are easy to under-triage. A patient may say "dizzy" when the real problem is diplopia, dysarthria, dysphagia, truncal ataxia, or evolving brainstem ischemia. SCRN candidates should listen for posterior clues and then decide what could harm the patient in the next hour.
Posterior circulation syndrome map
| Location | High-yield clues | Nursing concern |
|---|---|---|
| Midbrain | Eye movement problems, vertical gaze changes, altered arousal | Trend pupils, gaze, and level of consciousness. |
| Pons | Facial weakness, dysarthria, limb weakness, impaired horizontal gaze | Watch airway, aspiration, and progression to severe motor impairment. |
| Medulla | Dysphagia, hoarseness, hiccups, crossed sensory findings, ataxia | Keep NPO until swallow safety is known; escalate airway risk. |
| Cerebellum | Vertigo, vomiting, nystagmus, limb or truncal ataxia | Prevent falls and monitor for edema or hydrocephalus. |
| Occipital/PCA | Field cut, cortical blindness, visual confusion | Protect from injury and assess functional vision. |
Brainstem pattern recognition
Crossed signs are a classic clue: ipsilateral cranial nerve deficits with contralateral body weakness or sensory loss. Lateral medullary syndromes may include hoarseness, dysphagia, ipsilateral facial sensory loss, contralateral body sensory loss, vertigo, and ataxia. Pontine injury may impair facial movement, eye movement, and corticospinal tracts. Basilar artery occlusion can cause decreased consciousness, quadriparesis, and locked-in syndrome, where awareness is preserved but voluntary movement is nearly absent except vertical eye movement or blinking.
Cerebellar danger signs
Cerebellar strokes are not safe just because the patient can squeeze both hands. The posterior fossa has little room for swelling. A patient with severe occipital headache, repeated vomiting, inability to sit upright, new dysarthria, or decreasing arousal may be developing edema, brainstem compression, or obstructive hydrocephalus. Nursing answers that offer routine antiemetics and delayed reassessment are unsafe when the neurologic trend is worsening.
What to do at the bedside
Use B.E. F.A.S.T. fully. Balance and eye symptoms are not optional extras; they catch posterior events that face-arm-speech screens may miss. Keep the patient safe from falls, hold oral intake until swallowing is screened, assess cough and voice quality, and report cranial nerve findings clearly. If the patient has new dysphagia, drooling, weak cough, or decreasing arousal, airway protection becomes the priority.
For exam questions, separate benign dizziness from dangerous posterior circulation patterns. Isolated lightheadedness after standing is different from sudden continuous vertigo with diplopia, dysarthria, severe ataxia, or inability to walk. When posterior signs are present, choose escalation and focused neurologic assessment over reassurance.
Posterior circulation reporting
A focused report should include eye movement, pupils, speech quality, voice wetness, cough strength, swallowing status, limb coordination, truncal stability, gait if safely tested, headache, vomiting, and arousal. Posterior circulation deterioration can be abrupt, so the nurse should compare each reassessment with the prior baseline and escalate small but meaningful changes. Prior reports should be checked before accepting a change as baseline.
A patient reports sudden vertigo and double vision, cannot sit without falling to one side, and has slurred speech. What is the best SCRN-level interpretation?
A patient with lateral medullary findings has hoarseness, impaired gag, and wet voice quality. Which nursing priority follows from the syndrome?
A cerebellar hemorrhage patient who was alert now has repeated vomiting, worsening headache, and increasing drowsiness. What complication should the nurse suspect?