Bell’s palsy with facial bone involvement: A rare presentation of chronic nonbacterial osteomyelitis with literature review

Abstract

Chronic nonbacterial osteomyelitis (CNO) is a chronic, sterile, inflammatory disease. It primarily presents with nonspecific bone pain and swelling, but ultimately can cause bone destruction and deformities, if left untreated. The involvement of the cranial bones (apart from the mandible) is rare in CNO. In this report, we present a rare case of CNO affecting facial and cranial bones presenting as facial palsy with a review of the literature about similar affection. Summary of the case: A 10-year-old, previously healthy female was initially evaluated for swelling of the left side of her face with slight tenderness on palpation, but no fever. Her complete blood count was unremarkable, her inflammatory markers were elevated (CRP 7.5 mg/dl and ESR 104 mm/hr), and CT/MRI of the face and brain showed a destructive osseous process involving the left maxillary, zygomatic, sphenoid bones, and the clivus (figure 1:a & b). Bone biopsy of the left maxilla showed fibrous dysplasia with abscess formation, most consistent with an infectious etiology (acute osteomyelitis). She was started on oral Clindamycin for a 3 months course. The facial swelling improved after starting Clindamycin, but on her 6th week of treatment, she developed right-sided Bell’s palsy. An MRI of the brain showed hyperenhancement of the right 7th cranial nerve (figure 1:c). A month later, she was evaluated for right wrist and knee swelling, pain, and limitation of movement. Skeletal survey and MRI showed multifocal lesions with mixed sclerosis and lucency. Her inflammatory markers continued to be elevated. Another bone biopsy of the right radius showed similar findings of destruction with no evidence of malignancy. She was ultimately diagnosed with CNO. She was started on non-steroidal anti-inflammatory drugs (NSAIDs) with gastric protection and regular follow up. Over more than a year of follow-up, the patient’s inflammatory markers remain normal and joint swelling/limitation have remained in remission. Results: We found 5 additional cases (supplemental table 1) presented with similar presentation. To our knowledge, our patient is the first reported case in the US involving the cranial/facial bones apart from the mandible presenting with facial palsy. Conclusions: The affection of the facial bones (apart from the mandible) in CNO is very rare, but awareness of such presentation by the clinician is an important aspect of reaching the diagnosis.