Concurrent Isolated Hypoglossal Nerve Palsy Induced by Jugular Vein Thrombosis, Cervical Plexus Masses, and Vestibular Schwannoma: A Complex Case Report Highlighting Anatomical Pathways and Clinical Challenges

Abstract

Background: Hypoglossal nerve palsy is typically observed alongside other cranial nerve impairments, with isolated cases being infrequent and posing diagnostic complexities. Originating intracranially, the nerve traverses the skull and neck, governing tongue motility. Lesions are classified as supranuclear, nuclear, or infranuclear, engendering tongue deviation towards the affected side. Due to its proximity to crucial structures, hypoglossal nerve palsy often coincides with supplementary symptoms. Etiologies encompass skull base metastases, carotid artery pathologies, and trauma. This study explores less conventional triggers such as hypoglossal nerve palsy following thyroidectomy, jugular vein thrombosis, cervical plexus masses, and Vestibular Schwannoma. Case Description: A 38-year-old female presented to the Neurology outpatient clinic with leftward tongue deviation and left-sided neck and shoulder pain accompanied by stiffness that had begun several months prior. In addition to the tongue deviation, she reported minor dysphagia, blurry vision, and intermittent numbness on the left side of her scalp. MRI and duplex ultrasound verified the presence of left internal jugular vein (IJV) thrombosis. The patient was initially prescribed Eliquis and acetazolamide, with slight improvements in symptoms, though medication use ceased due to side effects. During a subsequent follow-up visit, persistent tongue deviation and worsening left shoulder pain prompted additional cervical imaging. A new cervical spine MRI revealed a 15x14 mm nodular dural enhancement with a paraspinal soft tissue mass at the C2 level. Concurrently, multiple cranial nerve palsies were detected during the physical examination. Unfortunately, the patient was subsequently diagnosed with breast cancer. To rule out brain metastases related to her breast cancer, an additional brain MRI was performed, revealing a newly formed 2.3x1.6x1.2 cm left cerebellopontine angle mass adjacent to the internal auditory canal (IAC), suggestive of a vestibular schwannoma but without evidence of metastatic disease. The patient's care involved a multidisciplinary team, including hematologist-oncologists, neurosurgeons, and neurologists. Conclusion: This case report highlights the less common causes of hypoglossal nerve palsy, such as jugular vein thrombosis, cervical plexus masses, and Vestibular Schwannoma. The persistence of the patient's palsy is attributed to the cumulative impact of these anatomical factors on the hypoglossal nerve. This underscores the diagnostic challenges posed by isolated hypoglossal nerve palsy and emphasizes the importance of comprehensive clinical evaluation and imaging for accurate diagnosis.