Which symptom pair is most associated with a posterior fossa tumor?

• A. Mutism and emotional liability
• B. Nystagmus and lack of upward gaze
• C. Nausea and ataxia
• D. Headaches and nerve IV palsy

Answer: (C)

The key idea is that posterior fossa tumors affect the cerebellum and brainstem, producing problems with coordination and balance along with vestibular symptoms. Nausea paired with ataxia best captures this pattern: the cerebellar dysfunction leads to unsteady, clumsy movements (ataxia), and the vestibular/ICP effects common with a posterior fossa mass contribute to nausea. Together, these two signs are the most characteristic cluster for a posterior fossa lesion.

Mutism and emotional lability can occur with cerebellar damage or after extensive posterior fossa surgery, but they are not the classic presenting pair for a tumor in this region. Nystagmus with lack of upward gaze points more to dorsal midbrain or brainstem involvement rather than a cerebellar/posterior fossa lesion. Headache with a trochlear (nerve IV) palsy could occur with raised intracranial pressure or brainstem pathology but is not as specifically tied to posterior fossa tumors as ataxia with nausea.