Numerous Severe Long-Term Sequelae of Skull Base Proton Beam Radiation for Infantile Clival Chordoma: An Illustrative Case Report

Background Pediatric clival chordoma is an exquisitely rare and atypical disease entity which displays more aggressive behavior than in adults including the rare ability to metastasize. Treatment regimens most frequently consist of maximal safe gross surgical resection followed by adjuvant proton beam radiation, with curative dose regimens approaching 70 Gy. Despite the apparent efficacy of proton beam skull base radiation for pediatric clival chordoma, its long-term sequelae are possibly numerous but poorly described. The difficulty in obtaining long-term follow-up is further complicated by the potential for markedly delayed presentation of complications.

Case Presentation We present a unique case of infantile clival chordoma treated successfully at the age of 10 months with subtotal surgical resection and adjuvant proton beam radiation to the skull base. Over 20 years later, despite ongoing local disease control, he presented to our tertiary care center for management of numerous severe long-term complications of skull base radiation: (1) Widespread osteoradionecrosis and osteomyelitis of the skull base, craniocervical junction, and temporal bone with cochlear dehiscence, superior semicircular canal dehiscence, and dehiscence of the petrous carotid canal; (2) intractable headaches, precipitating multiple hospital admissions; (3) hypoplasia of the midface, skull base, and temporal bones; (4) radiation-induced encephalomalacia; (5) hypothyroidism; (6) eustachian tube dysfunction and acute otomastoiditis, requiring primary mastoidectomy; (7) severe cholesteatoma with extension into the infratemporal fossa and parapharyngeal space resulting in aural-pharyngeal fistula requiring free flap reconstruction (complex anatomy with surgery complicated by internal carotid artery injury and embolization); (8) malnutrition, poor wound healing, and severe deconditioning, eventual failure and dehiscence of ear overclosure; (9) nasopharyngeal stenosis, chronic aspiration, and severe trismus with resultant G-tube dependence; and (10) critical difficulty with intubation ultimately resulting in tracheostomy dependence.

Discussion Despite maintaining local disease control for more than two decades, this patient’s osteoradionecrosis continues to be problematic. Due to this and numerous severe treatment-related sequelae, he is currently weighing aggressive skull base reconstructive options versus palliative care. Similar treatment effects have been described in the literature; however, predictors and optimal management of pediatric skull base radiation sequelae are elusive, highlighting need for further study and characterization with long-term follow-up.

Conclusion Skull base radiation in infancy poses several challenges related to numerous delayed, long-term sequelae of treatment. Disease control must be weighed against potential for severe adverse effects related to radiation of this anatomically complex region, and treatment at an experienced skull base center is recommended.