# Neurosarcoidosis > Neurosarcoidosis for NEET-SS Neurology: cranial neuropathy patterns, basal leptomeningeal MRI, biopsy strategy and steroid-sparing treatment. - Canonical URL: https://prepelephant.com/topics/neet-ss/neurology/neurosarcoidosis - Exam / course: NEET-SS · Subject: Neurology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Neurosarcoidosis", PrepElephant, https://prepelephant.com/topics/neet-ss/neurology/neurosarcoidosis ## Direct answer Granulomas that seed the nervous system produce neurosarcoidosis, whose commonest presentation is cranial neuropathy — facial palsy, often bilateral or recurrent — followed by basal leptomeningitis with headache and hydrocephalus, hypothalamic-pituitary infiltration with diabetes insipidus or amenorrhoea-galactorrhoea, parenchymal mass lesions, myelopathy, and a peripheral neuropathy that can mimic Guillain-Barré syndrome. Because isolated neurological sarcoidosis is uncommon, the diagnosis leans on proving systemic disease: chest imaging for bilateral hilar lymphadenopathy, cutaneous lesions such as erythema nodosum or lupus pernio, uveitis on slit-lamp examination, raised serum and CSF angiotensin-converting enzyme, and FDG-PET to find a biopsyable target. Histology — non-caseating granulomas — remains the gold standard. Treatment is prolonged high-dose corticosteroids with steroid-sparing agents (methotrexate, azathioprine, mycophenolate) and infliximab for refractory disease, and the great Indian caveat is tuberculosis, which imitates every single feature. ## What you must remember - **Cranial nerve hierarchy:** facial nerve (frequently bilateral, sometimes recurrent) first; optic nerve second with papilloedema or optic neuropathy; vestibulocochlear, trigeminal and multiple neuropathies follow. - **Basal meningeal picture:** gadolinium enhancement of the basal leptomeninges and optic chiasm on MRI, with headache, hydrocephalus (sometimes the presenting emergency) and cranial neuropathies in series. - **Neuroendocrine face:** hypothalamic and pituitary stalk involvement — diabetes insipidus, hyperprolactinaemia, sleep-wake and appetite disturbance; a thickened enhancing stalk on MRI is a signature. - **Systemic screen battery:** high-resolution chest CT (hilar nodes, interstitial pattern), ophthalmology for uveitis, skin examination, serum calcium and ACE, and CSF (lymphocytic pleocytosis, raised protein, ACE variably positive — oligoclonal bands may be present and do not exclude it). - **Diagnostic standards:** possible neurosarcoidosis requires a compatible syndrome with laboratory or histological systemic sarcoidosis; definite requires nervous-system histology (Zajicek framework) — biopsy reserved for accessible lesions or dangerous mimics. - **Treatment ladder:** prednisolone 0.5-1 mg/kg for months with slow taper (relapse-prone disease); methotrexate or azathioprine as steroid-sparing; infliximab for refractory; hydrocephalus and mass lesions may need neurosurgery. - **The tuberculosis shadow:** in India, basal meningitis with cranial palsies is tuberculous until excluded — contrast the CSF (low glucose with high protein and lymphocyte predominance favours TB), chest imaging, and where doubt persists, biopsy or a documented therapeutic decision made jointly. ## Working through a bilateral facial palsy A 34-year-old teacher develops left facial weakness, and three weeks later the right side follows — a bilateral lower motor neuron facial palsy, which is never Bell's palsy by definition. The screen for bilateral VII palsy is short and examinable: sarcoidosis, Lyme disease (travel history), Guillain-Barré variant (areflexia, albuminocytological dissociation), HIV and lymphoma/leukaemia. Her chest radiograph shows bilateral hilar fullness; slit-lamp examination reveals anterior uveitis; serum ACE is raised; CSF shows lymphocytic pleocytosis with protein elevation. She has Löfgren-spectrum systemic sarcoidosis with neurological involvement, and prednisolone 60 mg daily with a taper over six months, plus methotrexate after the second relapse, restores facial function. Had her MRI instead shown nodular enhancement along the basal cisterns with hydrocephalus and her CSF a low glucose, the working diagnosis in an Indian ward tilts decisively to tuberculous meningitis, and the management conversation is about anti-tubercular therapy duration and steroids — not an academic distinction, since infliximab in unrecognised disseminated tuberculosis could be catastrophic. ## Where candidates slip The error pattern is twofold: accepting "sarcoid-like" radiology without a systemic hunt (every presumed neurosarcoidosis case needs chest CT, eye examination and a biopsy of something reachable), and forgetting that CSF oligoclonal bands appear in sarcoidosis, wrongly hard-coding them to multiple sclerosis. The exam's favourite discriminating pair is neurosarcoidosis versus tuberculous meningitis — lymphocytic pleocytosis with normal glucose and enhancing stalk favour the former; low CSF glucose with basal exudates and chest consolidation favour the latter. For Indian candidates this is not exam trivia but ward reality, and a viva answer that mentions tissue confirmation before committing to months of immunosuppression earns its marks. ## Frequently asked questions ### Which cranial nerve is most commonly involved in neurosarcoidosis? The facial nerve, frequently bilaterally or recurrently — bilateral lower motor neuron facial palsy should always trigger a sarcoid screen. ### What MRI pattern is characteristic of neurosarcoidosis? Basal leptomeningeal and dural gadolinium enhancement, often with optic pathway involvement, hypothalamic-pituitary stalk thickening, hydrocephalus or enhancing parenchymal lesions. ### Which systemic findings support neurosarcoidosis? Bilateral hilar lymphadenopathy, uveitis, erythema nodosum or lupus pernio, hypercalcaemia and raised angiotensin-converting enzyme, with non-caseating granulomas on histology. ### Which first-line drug and which steroid-sparing strategy treat neurosarcoidosis? Prolonged oral prednisolone with slow taper, plus methotrexate or azathioprine for relapsing or steroid-dependent disease; infliximab for refractory cases. ### Why must tuberculosis be excluded before immunosuppressing a suspected neurosarcoidosis case? Tuberculous basal meningitis mimics the clinical and imaging picture, and steroids, methotrexate or infliximab can unmask disseminated tuberculosis.