Box 3.

Summary of investigations in ocular cranial palsies

Step 1. Neuroimaging in the form of Gadolinium-enhanced MRI brain and orbit (with fat-suppressed imaging) and use of newer modalities like constructive interference in steady state to trace individual cranial nerves. An angiogram is needed if there is suspicion of an aneurysm. Step 2:   ESR, C reactive protein, apart from complete blood count, renal and liver function tests, lipid profile, blood sugar, HbA1c, ECG, blood pressure monitoring.   ANCA, ANA, ACE levels, IgG4 levels (for inflammatory disorders).   Detailed nasal examination by an otorhinologist and nasal smear in all cases of CSS and orbital lesions (to rule out fungal etiology). If needed, nasal endoscopy can be done on a case-to-case basis.   CT paranasal sinuses to look for involvement of sinuses. Immediate debridement must be done, with maxillectomy/fronto-ethmoidectomy/orbital exenteration depending on the extent of the disease. Empirical amphotericin B can be started based on the intraoperative findings.   CT chest and abdomen or fluorodeoxyglucose/positron emission tomography (FDG-PET) scan of the whole body to rule out malignancy. PET also helps in looking for evidence of inflammation/infection elsewhere. For example, IgG4 diseases, sarcoidosis, and tuberculosis.   A tissue biopsy can be taken from the cranial or extracranial site with the help of CT/PET.