Pterygoid Meningoencephalocele in Adulthood as a Possible Manifestation of Dysembryogenesis of the Sphenoid Bone: A Case Report

Meningoencephalocele is a rare defect of the skull base in which brain tissue and meninges herniate through a bony defect. Skull base meningoencephaloceles are rare, particularly those not associated with the sphenoid sinus or other aerated anatomical structures. Due to their nonspecific clinical presentation, recognition is often delayed. The aim of this paper is to present a rare case of a meningoencephalocele of the middle cranial base with an atypical localization and clinical presentation. We present a 66‐year‐old patient who was treated at a tertiary otorhinolaryngology center for a meningoencephalocele of the left middle cranial base in the region of the pterygoid process of the sphenoid bone. The disease manifested solely as a chronic, nonproductive cough resistant to pharmacological treatment, which for several years had been attributed to asthma. The patient had no history of craniofacial trauma, prior skull base surgery, or risk factors for elevated intracranial pressure. Clinical ENT and neurological examinations revealed no abnormalities. MRI and CT of the head, performed for other indications, later confirmed the presence of a meningoencephalocele. The patient was successfully treated with a transnasal endoscopic surgical approach with skull base reconstruction, after which the cough resolved immediately. The presented case of a pterygoid meningoencephalocele of the middle cranial base at an atypical location within the sphenoid bone demonstrates that meningoencephaloceles may present without involvement of aerated anatomical structures and without typical signs of cerebrospinal fluid (CSF) leakage. In our patient, CSF leakage manifested exclusively as chronic cough, leading to a delayed diagnosis. Given the absence of risk factors for intracranial hypertension, this case raises consideration of dysembryogenesis of the sphenoid bone as a possible cause of meningoencephalocele formation. This report highlights the importance of considering rare causes of persistent, unexplained symptoms and confirms the transnasal endoscopic surgical approach as an effective treatment method.