Resident Physician PGY2 Olive View-UCLA Medical Center Hawthorne, California, United States
Case Diagnosis: 71-year-old male who presented with pulsatile tinnitus in the setting of retrocerebellar arachnoid cyst.
Case Description: 71-year-old male presented to acute rehabilitation for heart failure exacerbation. He endorsed chronic headaches and bilateral hearing loss attributed to working in an automotive garage. Therapy sessions were paused due to bothersome pulsating pressure along the bilateral cranium. This worsened with lateral eye movements and head rotation. He denied room spinning sensation, cervicalgia, headaches, nausea, dizziness, nor vision changes. Such episodes occurred over the past two years intermittently.Neuro-optometry, audiology, and otologic exams were negative for acute processes. Given cardiac hardware and kidney disease, Brain MRI and CT angiography were contraindicated. CT head non-contrast incidentally revealed a 4.4cm arachnoid cyst posterior to the left cerebellum. Neurology recommended outpatient neurosurgical evaluation for cyst resection. After failing a meclizine trial, acetazolamide 125mg twice a day was started and titrated to 500mg twice a day over two weeks. This significantly decreased symptom severity and frequency, though emotional stress still caused exacerbations.
Discussions: Pulsatile tinnitus can be due to vascular or non-vascular pathologies. Our case highlights arachnoid cysts, a benign collection of cerebrospinal fluid (CSF) within the arachnoid layer of the meninges, as a potential non-vascular etiology. In our patient, we propose that the cyst may have generated a mass effect against the vestibulocochlear nerve and impaired CSF flow. Bilateral rotation of the head and neck may have temporarily caused mechanical narrowing of the tissue space - causing the patient’s symptoms. Thus, acetazolamide treatment was likely effective due to its reduction of intracranial CSF and consequent pressure on the vestibulocochlear nerve. In acute rehabilitation, this would allow for symptom and therapy optimization, as neurosurgical interventions may be deferred until after discharge.
Conclusions: Pulsatile tinnitus can be associated with arachnoid cysts that cause nerve compression. Acetazolamide may prove beneficial in symptom alleviation.
