A 74-year-old woman develops occipital headache, vomiting, and dizziness. She looks unwell, her blood pressure is 180/100 mm Hg, pulse is 70/min, and respirations are 30/min. She is unable to sit or walk because of unsteadiness. Over the next few hours, she develops a decline in her level of consciousness.For the above patient with altered level of consciousness, select the most likely diagnosis.

**Core Concept**
Occipital headache, vomiting, dizziness, unsteadiness, and rapid decline in consciousness are classic signs of cerebellar hemorrhage. The cerebellum controls balance and coordination, and its hemorrhage often presents with ataxia, vertigo, and altered mental status due to increased intracranial pressure and mass effect.

**Why the Correct Answer is Right**
Cerebellar hemorrhage typically occurs in the posterior fossa and causes sudden onset of vertigo, ataxia, and nausea. The patient’s unsteadiness and inability to walk point to cerebellar dysfunction. As the hemorrhage expands, it compresses the brainstem and increases intracranial pressure, leading to a rapid decline in consciousness. The occipital headache may be due to meningeal irritation or secondary effects. This pattern is distinct from basal ganglia or pontine hemorrhages, which present with different neurological deficits.

**Why Each Wrong Option is Incorrect**
Option A: Basal ganglia hemorrhage often presents with hemiparesis, hemisensory loss, and focal weakness, not ataxia or dizziness. It is less likely to cause acute confusion or loss of balance.
Option C: Pontine hemorrhage causes locked-in syndrome, cranial nerve deficits, and sudden respiratory changes, not ataxia or unsteadiness.
Option D: Lobar intracerebral hemorrhage typically presents with focal neurological deficits, hemiplegia, and seizures, not balance issues or vertigo.

**Clinical Pearl / High-Yield Fact**
In elderly patients with sudden vertigo, ataxia, and altered mental status, cerebellar hemorrhage should be considered first—especially when there is no history of hypertension or stroke. Early imaging is critical to avoid misdiagnosis.

✓ Correct Answer: B. cerebellar hemorrhage

✓ Correct Answer: B. cerebellar hemorrhage