unilateral sixth nerve palsies as early presenting signs of metastatic prostatic carcinoma AbstractPurpose To report four cases of cranial nerve palsy, which presented to the ophthalmologist as the only or one of the earliest manifestations of prostatic carcinoma. This is an infrequent complication of metastatic prostatic carcinoma usually only occurring late in the disease process in those with a history of prostatic carcinoma. Methods The case records of four patients with a history of a cranial nerve palsy who attended the ophthalmology department and who had a recent or subsequent diagnosis of prostatic carcinoma were reviewed. Results Diplopia caused by lesions affecting the third and sixth nerves sometimes in association with sensory symptoms may be a manifestation of metastatic prostatic carcinoma. These findings are consistent with base of the skull metastases from the condition.Two patients are still alive 54 months and 12 months after the diagnosis. One of the patients died 13 months after the diagnosis of prostatic carcinoma was made and the other died 21 months after the diagnosis from an unrelated hypertensive brain haemorrhage. Conclusion Any patient presenting with diplopia must have an adequate past medical history taken and in an elderly gentleman this should include symptoms of prostatic disease. If indicated urological referral and measurement of prostate specific antigen may be performed.In patients whose cranial nerve palsy is complicated by other sensory signs or those in whom no sign of recovery occurs in 2 months, a contrast CT scan asking for bone windows to be included may be helpful in delineating any pathology. Keywords: cranial nerve palsies; base of the skull metastases; prostatic carcinoma; bilateral third nerve palsies; radiotherapy; prostate specific antigen Base of the skull metastases are a rare but documented late complication of metastatic prostatic carcinoma, which can give rise to cranial nerve palsies. 1 We report four cases, which were unusual in that the nerve palsy was the presenting feature of the disease in two cases and a recent diagnosis of prostatic carcinoma had been made in the other two. Case reports Case 1A 66-year-old male presented with facial tingling, which resolved and was followed by the onset of diplopia.Extraocular movements revealed limitation of upgaze, adduction and depression in both eyes with full abduction. Slight bilateral ptosis was noted. The right pupil was dilated and unreactive to light and accommodation but the left pupil was normal. The remainder of the physical and neurological examinations were unremarkable. Investigations (blood