Meningiomas are the most common primary tumours of the central nervous system,1,2 with a prevalence of 97.5 per 100,000 population.¹ They are typically benign and cause symptoms by compression. Foramen magnum meningiomas account for 1.8–3.2% of all meningiomas.3,4 Neuromyelitis optica spectrum disorders (NMOSD) are inflammatory autoimmune diseases of the central nervous system, primarily targeting the optic nerves and spinal cord, with a prevalence as high as 10.0 per 100,000 population.5 Approximately 20% of people with NMOSD are seronegative for aquaporin-4 antibodies and up to 75% of these patients are also seronegative for myelin oligodendrocyte glycoprotein antibodies.6 NMOSD may coexist with other organ-specific or systemic autoimmune disorders, including Sjögren’s syndrome (SS). Whilst the exact prevalence of this overlap is unknown, SS, systemic lupus erythematosus, and myasthenia gravis are the most frequently reported systemic autoimmune diseases associated with NMOSD.7-9
The authors report the case of a 52-year-old male who had had recurrent cervical and thoracic myelitis for 12 years, compatible with seronegative NMOSD overlap with primary SS. He achieved sustained clinical remission following immunosuppression with cyclophosphamide (pulses: 8; total dose per pulse: 800 mg/m2; no notable side-effects). He was admitted for paresthesia in the cervical dermatomes and limb weakness, which had developed over the previous month. The neurological examination revealed bilateral C2 hypoesthesia, tetrameric hypopallesthesia, and mild tetraparesis predominantly in the lower limbs. MRI of the cervical spine showed a voluminous contrast-enhancing epidural mass, consistent with a foramen magnum meningioma, that was compressing the C1–C2 spinal cord and medulla. Mild signal changes consistent with myelopathy were also present in the corresponding spinal cord segments. High-dose methylprednisolone brought no significant improvement and did not preclude the clinical progression. The patient underwent minimally invasive surgery with complete excision of the tumour. The neuropathology diagnosis was benign meningioma. Postoperatively he recovered completely.
Foramen magnum meningiomas are rare, representing 2.5% of all meningiomas. The mean age at the time of diagnosis is 55 years, similar to this present case. However, they can occur in any age group. There is no established association between meningioma and NMOSD or primary SS. On account of the patient’s history of recurrent cervical and thoracic myelitis, the possibility of cervical myelitis was also considered. Nevertheless, the lack of signal change in the cervical cord suggesting recent myelitis and the complete remission following removal of the meningioma argue against this diagnosis. The predominance of weakness in the lower limbs is atypical considering the somatotopy of the corticospinal tracts with the pattern expected with spinal cord compression from periphery to centre and from the posterior to the anterior facet. In this case, it might be inferred that changes from previous myelitis may have resulted in the clinical expression of an otherwise subclinical lesion.
This case illustrates the importance of accurate clinical assessment and that of ascertaining anatomoclinical correlation for an early diagnosis and prompt therapeutic management.