A 52-year-old man has noticed over six months that his left ear is going deaf, and recently he feels unsteady. His family says his eyes jerk strangely — big jerks when he looks left, tiny jerks when he looks right. He also feels numbness on the left side of his face. He is otherwise well.
Examination Findings
A 52-year-old man with six months of progressive hearing loss in the left ear and recent unsteadiness. Eye movements: on left gaze, a coarse large-amplitude jerk nystagmus beating left; on right gaze, a fine small-amplitude jerk nystagmus beating right. Reduced corneal sensation on the left, mild left facial weakness. Audiometry: left sensorineural hearing loss. No papilloedema currently.
Investigations
MRI of the brain with dedicated internal auditory meatus views is urgent — it reveals the cerebellopontine angle mass. Pure-tone audiometry documents the sensorineural loss. Full cranial nerve examination maps the extent (V, VII, VIII commonly involved). Baseline vestibular and neurological assessment completes the picture before neurosurgical referral.
Questions to Think About
- What makes this nystagmus pattern localise to the cerebellopontine angle?
- Why do the hearing loss and facial signs matter as much as the eye movements?
- What is the urgent investigation and why?
Diagnosis
Bruns nystagmus secondary to a left cerebellopontine angle tumour — coarse nystagmus looking toward the lesion, fine nystagmus looking away.
Reasoning
Reasoning: A gaze-dependent nystagmus that is coarse toward one side and fine toward the other, combined with ipsilateral sensorineural hearing loss and facial nerve signs, is Bruns nystagmus from a cerebellopontine angle tumour — the coarse component reflects the vestibular lesion, the fine component the cerebellar involvement. It is not vestibular neuronitis (chronic progressive course with auditory and facial signs) and not drug-induced (asymmetric, with cranial nerve findings). Diagnosis: Bruns nystagmus secondary to a left cerebellopontine angle lesion. Management: typical management is urgent MRI and neurosurgical referral per local protocol; the eye findings serve as localising and monitoring signs through treatment.
Differential Diagnosis
- Vestibular neuronitis — ruled out: no acute vertigo episode, the nystagmus is direction-changing with gaze, and there are auditory and facial signs.
- Infantile nystagmus — ruled out: adult onset with a gaze-dependent asymmetric pattern and associated cranial nerve signs.
- Drug-induced nystagmus — ruled out: no relevant medication, and the marked asymmetry with hearing loss points to a structural lesion.
Management
Typical management includes urgent neurosurgical referral for the cerebellopontine angle lesion per local protocol — the nystagmus is managed by treating the cause. Audiology and facial nerve function are monitored. The patient is counselled about the diagnosis, the treatment options (surgery, radiosurgery per local protocol), and the expected effects on hearing and balance. Ophthalmic follow-up tracks the nystagmus as a marker of brainstem/cerebellar recovery.
Key Learning Points
- Bruns nystagmus is direction-changing with gaze: coarse toward the lesion, fine away — a hallmark of cerebellopontine angle tumours.
- Unilateral hearing loss plus nystagmus plus facial signs localise to the cerebellopontine angle.
- The combination of gaze-evoked (cerebellar) and vestibular components in one patient is the clue.
- Any adult with asymmetric hearing loss and nystagmus needs MRI of the internal auditory meatus.
Red Flags
- Progressive unilateral hearing loss with imbalance — cerebellopontine angle lesion until imaged.
- New facial weakness or trigeminal numbness — the lesion is involving more cranial nerves; expedite.
- Headache, vomiting or papilloedema developing — hydrocephalus from a large lesion; emergency.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.