Neurosarcoidosis With Cranial Nerve Polyneuropathy: A Case Report Highlighting the Potential Role of Serial Systemic Immune-Inflammatory Indices (SSIIi)

Neurosarcoidosis is an uncommon but serious manifestation of systemic sarcoidosis, often posing a diagnostic challenge due to its varied presentation and the absence of definitive testing. This case report outlines a rare presentation of neurosarcoidosis and the comprehensive diagnostic process used to confirm the diagnosis. A 51-year-old woman presented with acute cranial nerve polyneuropathy involving the facial (VII), oculomotor (III), and trigeminal (V) nerves. These acute neurological deficits were accompanied by systemic constitutional symptoms, including weight loss and fatigue. Initial neuroimaging, including MRI of the brain, revealed neuritis of the right facial nerve. CT imaging of the thorax revealed extensive mediastinal and hilar lymphadenopathy. Abdominal imaging revealed signs of infiltrative liver disease. These findings shifted the diagnostic focus toward systemic granulomatous diseases. Differential diagnoses included tuberculosis, lymphoma, and other infiltrative or autoimmune conditions. A lumbar puncture and comprehensive serological investigations were undertaken, and these results were used to rule out infectious and malignant etiologies. To establish histological confirmation, an endobronchial ultrasound-guided biopsy of a subcarinal lymph node was performed. Histopathology demonstrated non-caseating granulomatous inflammation, confirming a diagnosis of sarcoidosis in the appropriate clinical and radiological context. The patient was commenced on oral corticosteroid therapy with significant improvement in both neurological symptoms and overall clinical status. This case highlights the need for a high index of suspicion for neurosarcoidosis in patients presenting with multiple cranial nerve palsies, especially when accompanied by systemic symptoms and abnormal imaging findings. A novel aspect of this report is the serial measurement of the patient's Systemic Immune-Inflammatory Indices (SSIIi) during hospitalization. These values, calculated from routine full blood count parameters, fluctuated in relation to clinical status and treatment initiation. This trend suggests that SSIIi may serve as a dynamic, non-invasive marker of disease activity in sarcoidosis, especially in settings where repeated imaging or tissue sampling is not feasible. Further research is warranted to validate the utility of SSIIi as a monitoring tool in neurosarcoidosis.