Tubercular Optochiasmatic Arachnoiditis

What is your diagnosis?"nA 25-year-old woman presented with a low-grade fever, loss of weight and appetite of 4 months duration and intermittent vomiting of two months duration. The diagnosis was tubercular meningitis and the patient was on anti-tubercular therapy from one month. Two weeks ago, a rapidly progressive visual loss emerged in two days. In general observation, she was thin, had mild pallor and no icterus, was conscious and also irritable. In physical examination, she was febrile (100o F), there were bilateral crepitations in the chest and she had mild neck rigidity. On eye examination, there were bilateral dilated sluggishly reacting to light pupils, no projection or rays or perception of light in both eyes, the fundus showed bilateral papilloedema with features of secondary optic atrophy. Extra ocular movements were restricted in all directions suggestive of 3rd, 4th and 6th nerve paresis. Other cranial nerves were normal. There were no focal motor or sensory deficits. Blood investigations were normal except for a raised erythrocyte sedimentation rate (64 mm in the 1st hour). Three consecutive samples of sputum for acid fast bacilli were negative. The brain CT scan showed mild dilation of the third and lateral ventricles and thick basal exudates (Fig. 1.A&B). MRI of the brain showed hypertrophy of the chiasma and the cisternal segment of both optic nerves after contrast enhancement (Figs. 2&3).