A 25-year-old young man who was a cleaner by occupation coming from a low middle-class family attended at outpatient department of chittagong eye infirmary and training complex Institute with a history of sudden painless vision loss in his left eye for 20 days. He did not give any significant past medical history. He was a smoker who used to take 1 pack per day. He was neither a drug user nor had any history of alcohol intake. At first, he denied any sexual exposure but eventually agreed.
On examination, visual acuity of the right eye was 6/6 and the left was 6/60. Both pupils were round and regular. Direct and consensual reactions of both eyes were normal. The left pupil showed a relative afferent pupillary defect. Color vision by Ishihara test on the right eye, he read all plates but on the left eye, he could identify only two plates. The anterior segment of both eyes was found normal. The posterior segment showed a hyperemic left optic disc, margin blurred, swollen, and nerve fiber layer edema [Figure 1a and b]. Fluorescence angiography showed hyperfluorescence of the left optic disc indicating edema, and the rest of the retina of both eyes was within normal limits [Figure 2]. Routine blood tests, urine tests, random blood sugar, and magnetic resonance imaging (MRI) of the brain were within normal limits. He was diagnosed with optic neuritis in the left eye and injectable corticosteroid was given for 3 days followed by oral corticosteroids as per the schedule of optic neuritis. His vision was gradually improving within 1 month and became 6/9 on his left eye. However, after a month, the patient returned with a blurring of vision in the same eye for 3 days. An extensive blood test was done including the Monteux test, C-reactive protein, venereal disease research laboratory (VDRL) test, T. pallidum hemagglutination assay (TPHA), and HIV serology. Notably, we also performed serum autoimmune antibody neuromyelitis optica immunoglobulin-G (NMO-IgG)/antibody to aquaporin-4 to exclude NMO, which was found negative. No abnormality was detected in all other blood tests except VDRL and TPHA in blood were found positive. TPHA had a high titer (1:1280 dilutions) and rapid plasma reagin (RPR) titer (1:64 dilutions) was also high. The patient then admitted having had a history of unprotected commercial sex 1 year ago, after which he had a single, painless ulcerated penile lesion healed without any antibiotic treatment. He did not notice any later symptoms attributable to secondary syphilis. We also examined but did not find any local genital skin lesions. Then, he was advised to do a cerebrospinal fluid (CSF) study. The CSF analysis showed leukocytosis (80 cu/mm lymphocyte), and VDRL and TPHA were found positive with TPHA titer found 1: 80 dilutions. RPR was also reactive. The biochemistry examination of CSF showed glucose 55 g/dl and protein 45 g/dl. No bacteria were found including tuberculosis. Adenosine di aminase was also negative (<5 U/L). Based on these clinical and laboratory examinations, he has been diagnosed with a case of neurosyphilis with optic neuritis.
The ideal treatment of neurosyphilis is intravenous (IV) injection of 3-4 million units of aqueous crystalline penicillin at every 4 h for 10-14 days or intramuscular injection of 2.4 million units penicillin G procaine daily along with oral 500 mg probenecid four times daily for 10-14 days. However, penicillin formulations are not currently available in our country. Therefore, as an alternative treatment, IV 2 g ceftriaxone had been given for 14 days. The systemic steroid was also administered under the coverage of antibiotics. The patient's visual acuity was improved within 1 month. On the left eye, it was 6/9, could read five plates of Ishihara chart and the optic disc showed mild edema, which are the signs of improvement. He was advised to repeat VDRL, TPHA, and CSF study after 3 months.