What is the management and treatment of Bruns nystagmus?

Management and Treatment of Bruns Nystagmus

Bruns nystagmus requires treatment of the underlying cerebellopontine angle tumor or lesion causing brainstem compression, typically through surgical resection of the mass, as this is the only definitive treatment to address the root cause of the condition.

Clinical Characteristics and Pathophysiology

• Bruns nystagmus is defined as a bidirectional nystagmus characterized by coarse, high-amplitude horizontal nystagmus with low oscillatory frequency when looking toward the side of the lesion, and fine, low-amplitude, high-frequency nystagmus when looking away from the lesion 1
• It is typically associated with large cerebellopontine angle tumors (≥3 cm in diameter) that cause significant brainstem distortion, compression of the flocculus and/or vestibulocerebellum 2, 3
• While most commonly seen with vestibular schwannomas, it can also occur with other cerebellopontine angle masses and rarely with pontine infarction 4

Diagnostic Approach

• MRI of the brain is the preferred imaging modality for evaluating nystagmus, particularly when a cerebellopontine angle tumor is suspected 5
• CT has limited value in the initial evaluation of nystagmus but may be used when MRI is contraindicated 6
• In patients with vestibular schwannomas, Bruns nystagmus is associated with tumors larger than 3.5 cm in maximum diameter (92% of these patients have nystagmus, with 67% specifically having Bruns nystagmus) 2
• Fourth ventricle displacement on neuroimaging is present in nearly all cases (89%) 3

Treatment Algorithm

1. Surgical Management (Primary Treatment):

   • Surgical resection of the underlying cerebellopontine angle tumor is the definitive treatment for Bruns nystagmus 2
   • The goal is to relieve brainstem compression and reduce mass effect on the vestibulocerebellar structures 1

2. Symptomatic Management (Pre-surgical or if surgery is contraindicated):

   • Medications that may provide symptomatic relief for nystagmus include:
     • 4-aminopyridine for downbeat and upbeat components of nystagmus 7
     • Memantine or gabapentin for pendular components 7
     • Baclofen for periodic alternating components 7

3. Post-surgical Management:

   • Monitor for resolution of nystagmus, which typically improves following successful tumor removal 2
   • Balance rehabilitation therapy may be beneficial as 95% of patients with Bruns nystagmus have preoperative balance impairment 2

Prognosis

• After surgical treatment, patients with Bruns nystagmus typically show significant improvement in balance status 2
• Long-term balance outcomes following surgery are generally similar to those of patients with no nystagmus or other forms of nystagmus 2
• The nystagmus itself usually resolves or significantly improves after successful tumor resection, though in rare cases it may persist postoperatively 1

Important Clinical Considerations

• Bruns nystagmus should not be confused with other forms of nystagmus such as convergence retraction nystagmus, which is associated with dorsal midbrain syndrome 6
• In rare cases, Bruns nystagmus can occur as a new postoperative finding after resection of a giant cerebellopontine angle tumor despite complete surgical resection 1
• While typically associated with tumors, Bruns nystagmus has been reported in cases of pontine infarction, suggesting that any process causing significant brainstem distortion can potentially produce this pattern of nystagmus 4

Pitfalls to Avoid

• Failure to recognize Bruns nystagmus as a sign of a large cerebellopontine angle tumor can lead to delayed diagnosis and treatment 3
• Focusing solely on the nystagmus without addressing the underlying cause will not provide long-term resolution 2
• Overlooking balance impairment, which is present in 95% of patients with Bruns nystagmus and requires specific rehabilitation strategies 2