Facial nerve compression by the posterior inferior cerebellar artery causing facial pain and swelling: a case report

INTRODUCTION We report an unusual case of facial pain and swelling caused by compression of the facial and vestibulocochlear cranial nerves due to the tortuous course of a branch of the posterior inferior cerebellar artery. Although anterior inferior cerebellar artery compression has been well documented in the literature, compression caused by the posterior inferior cerebellar artery is rare. This case provided a diagnostic dilemma, requiring expertise from a number of specialties, and proved to be a learning point to clinicians from a variety of backgrounds. We describe the case in detail and discuss the differential diagnoses. CASE PRESENTATION A 57-year-old Caucasian woman with a background of mild connective tissue disease presented to our rheumatologist with intermittent left-sided facial pain and swelling, accompanied by hearing loss in her left ear. An autoimmune screen was negative and a Schirmer's test was normal. Her erythrocyte sedimentation rate was 6mm/h (normal range: 1 to 20mm/h) and her immunoglobulin G and A levels were mildly elevated. A vascular loop protocol magnetic resonance imaging scan showed a loop of her posterior inferior cerebellar artery taking a long course around the seventh and eighth cranial nerves into the meatus and back, resulting in compression of her seventh and eighth cranial nerves. Our patient underwent microvascular decompression, after which her symptoms completely resolved. CONCLUSION Hemifacial spasm is characterized by unilateral clonic twitching, although our patient presented with more unusual symptoms of pain and swelling. Onset of symptoms is mostly in middle age and women are more commonly affected. Differential diagnoses include trigeminal neuralgia, temporomandibular joint dysfunction, salivary gland pathology and migrainous headache. Botulinum toxin injection is recognized as an effective treatment option for primary hemifacial spasm. Microvascular decompression is a relatively safe procedure with a high success rate. Although a rare pathology, posterior inferior cerebellar artery compression causing facial pain, swelling and hearing loss should be considered as a differential diagnosis in similar cases.