A case of osteopathia striata with cranial sclerosis with facial nerve palsies

Osteopathia striata with cranial sclerosis (OS-CS; OMIM#300373) is a rare disease with a prevalence of 0.1 in 1 million individuals. It is also an X-linked dominantly inherited bone dysplasia.1 Mutations in WTX encoding Wilms tumor on the X chromosome, also known as AMER1/FAM123B, cause the disease.2 Osteopathia striata with cranial sclerosis is characterized by craniofacial hyperostosis and longitudinal striations of long bones.3 Common phenotypes of this disease include cleft palate and craniofacial dysmorphisms, including macrocephaly, hypertelorism, and flat nasal bridge.1, 2 Common complications include ophthalmoplegia, hearing loss, and chronic otitis media.1 However, facial nerve palsy is a rare complication of this condition,1, 3 and there have been no reports of recurrent facial nerve palsy. We report a case of OS-CS in a patient harboring a WTX deletion who experienced facial nerve palsy three times. Temporal bone computed tomography (CT) showed narrowing of the facial nerve canals. Consent for reporting this case was obtained from the patient's parents. The patient was a 12-year-old female who was the first child of healthy non-consanguineous parents. The pregnancy was uneventful; however, sonography revealed bilateral cleft lips. The patient was born at 41 weeks of gestation. Her birthweight was 3244 g, birth height was 49.3 cm, and head circumference was 36.2 cm (+2.0 SD). She had bilateral cleft lip and palate, hypertelorism, and a flat nasal bridge. She had no organ malformations. She also had a speech delay and her intelligence quotient was 48 on the Tanaka–Binet Intelligence Scale at 4 years of age. Audiometry revealed no hearing loss at 11 years of age. At 4 years, she underwent a radiographic examination for a bruised knee and was suspected of having OS-CS because of the presence of longitudinal striations on the distal end of the femur. Genetic testing was performed after obtaining informed consent from the parents. Direct sequencing of WTX showed no variations. However, the heterozygous deletion of WTX was observed via multiplex ligation-dependent probe amplification using previously reported probes.2 No abnormalities were observed in the ASB12, ARHGEF9, and MTMR8 loci adjacent to WTX. At 2 months of age, she had bilateral otitis media and bilateral facial nerve palsy. Oral amoxicillin-clavulanate was administered for 1 week as treatment for the otitis media. Three weeks of oral prednisolone (PSL) was administered for facial nerve palsy, and her symptoms improved. At 4 years of age, she had an acute exacerbation of left chronic otitis media, resulting in left peripheral facial nerve palsy. Her symptoms improved after 5 days of cefcapene peroxyl and 10 days of oral PSL administration. A temporal bone CT scan performed at 5 years of age showed that the bilateral facial nerve canal was narrow, approximately 0.7 mm, and was not delineated distal to the mastoid segment (Supporting Information, Figure S1A,B). The symptoms of right facial nerve palsy developed at 11 years of age. Nevertheless, there was no evidence of otitis media. A temporal bone CT showed further narrowing of the bilateral facial nerve canal to a diameter of 0.5 mm in the most narrowly defined area (Supporting Information, Figure S1C,D). After the disease onset, oral PSL was administered for 1 month; however, the right forehead crease remained incomplete 1 year after the disease onset. Auditory acuity was less than 20 decibels bilaterally. The patient had no hyperacusis, or taste and salivary secretion disorders. In this case, temporal bone CT showed progressive narrowing of the facial nerve canal. We hypothesized that bone thickening due to OS-CS compressed the facial nerve and made it vulnerable to facial nerve palsy. The first and second facial nerve paralysis may have been symptomatic because the inflammation of otitis media temporarily affected the mucosa edema of the facial nerve canal. We speculate that facial paralysis improved because of the disappearance of the mucosal edema caused by the improvement in otitis media. The third episode may have been caused by the compression of the facial nerve. As far as we are aware, so far only six cases have been reported for OS-CS with facial nerve palsy, including ours1-5 (Table 1). Temporal bone CT taken in another case also revealed a narrowed facial nerve canal. In our case, temporal bone CT showed progressive narrowing of the facial nerve canal over time, which may have worsened the treatment response. Hirokazu Yamagishi wrote the manuscript. Michigami and Tachikawa performed the genetic analysis. Yukifumi Monden and Yasuyuki Nozaki were responsible for patient treatment. Yukifumi Monden, Hitoshi Osaka, and Yasuyuki Nozaki contributed to the conception of this study. Yukifumi Monden, Hitoshi Osaka, Toshimi Michigami, Kanako Tachikawa, and Toshihiro Tajima critically reviewed the manuscript and supervised the report. All the authors have read and approved the final version of the manuscript. The authors declare no conflict of interest. Figure S1. Temporal bone CT findings of facial nerve canal at 5 years and 11 years of age. 1A: Right facial nerve canal at 5 years of age (sandwiched by white arrowheads). The diameter was approximately 0.7 mm and was not delineated distal to the mastoid segment. The mastoid was low, contained air, and was filled with bone (surrounded by a white dashed line). 1B: Left facial nerve canal at 5 years of age (sandwiched by white arrowheads). The diameter was approximately 0.7 mm and was not delineated distal to the mastoid segment. Fluid retention in the middle ear (white asterisk). 1C: Right facial nerve canal at 11 years of age (sandwiched by white arrowheads). The diameter was approximately 0.5 mm and was not delineated distal to the mastoid segment. Almost no air content was noted in the mastoid (surrounded by a white dashed line). 1D: Left facial nerve canal at 11 years of age (sandwiched by white arrowheads). The diameter was approximately 0.5 mm and was not delineated distal to the mastoid segment. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.