Diabetes mellitus-associated ocular motor nerve palsies.

E diagnosis of ocular motor palsy enables prognosis and assists in treatment. In adults, the most common causes of ocular motor palsy are aneurysm, microvascular disease (such as diabetes mellitus [DM]), and trauma. In patients with DM, ocular motor nerve palsy is a common cause of acquired diplopia and/or ptosis.1,2 In diabetics, the calculated incidence of cranial nerves palsies is 5-10 times higher than in non-diabetics. Approximately 1-14% of diabetics have ocular motor nerves palsies during the course of the disease.3 The purpose of this study was to describe the demographic and the clinical characteristics of ocular motor nerves palsies in diabetics, to access associated risks factors, as well as, to determine the value of neuroimaging in these patients. Medical files of patients with ocular motor nerve palsies admitted to the Department of Neurology and Ophthalmology of the University Hospital of Monastir, Monastir, Tunisia, between January 1997 and December 2007 were analyzed. Patients were included in this study if DM was identified to be the etiology of ophthalmoplegia. The following data were collected from patients’ files: age, gender, date of onset, and type of cranial nerve palsy, type and duration of DM, presence or absence of diabetes retinopathy, and other vascular risk factors (arterial hypertension, hyperlipemia, and coronary artery disease). The results of cerebral neuroimaging (brain CT scan and/or MRI) were also recorded. The data were analyzed using the Epi-Info 6 database program. Results were expressed as mean ± SD values. Sixteen patients with DM associated ocular motor nerve palsies were recorded. There was a female predominance (12 female, and 4 male patients) with a mean age of 67 ± 13.9 years (range from 30-89 years). In 13 patients, DM was type 2, and type one in the other 3 cases. All patients complained of acute diplopia with headaches. A partial or complete extrinsic palsy of the third cranial nerve was seen in 13 patients. This third cranial nerve palsy was isolated in 11 patients, and associated to other ocular motor cranial nerve palsies’ in 2 cases. Isolated sixth cranial nerve palsy was seen in 3 patients (patients 4, 5, and 6). In the remaining 2 cases, there was a palsy of at least 2 nerves (patient 10 has a third and sixth nerves palsy; palsy of the third, fourth, and sixth nerves was found in patient one). Data of patient’s are summarized in Table 1. A long history of DM was observed in all patients, with a mean duration of 16 ± 5.8 years (range from 5-27 years). Other vascular risk factors or chronic diseases were also recorded: arterial hypertension (AHT) in 9 patients, and hyperlipemia in 4 cases. Diabetic retinopathy was observed in 10 patients from 16. The brain CT scan performed in 9 patients was normal in 8 and showed an old ischemic infract in the left cerebellum in patient l4. Brain MRI performed in 5 patients (during the first 2 weeks after clinical symptoms onset), showed lacunar infarcts in the brain stem, which can explain cranial nerve paralysis in patients 6, 10, and 11. This exam was normal or showed old lacunar infarcts in patients 5 and 16. In the present study, we report 16 patients with DMassociated ocular motor nerve paralysis. The mean age at onset was of 67 ± 13.9 years. These palsies occurred mainly in female patients. Acute diplopia and headaches were the main complaints. The third cranial nerve was the most frequently involved nerve, followed by the sixth, and only patient one had a fourth nerve palsy associated to the third and the sixth nerves involvement. The diabetic ophthalmoplegia occurred more frequently in DM type 2 than in type one. It also occurred more frequently in patients with a long history of DM with a mean duration of 16 ± 5.8 years, and associated to other vascular risk factors. Neuroimaging (brain CT scan or MRI), performed in the acute period was usually normal, or showed in 3 patients brain stem infarcts, which can explain clinical symptoms. All these clinical characteristics of DM ophthalmoplegia, including mean age at onset of palsy and duration of DM were similar to previous reports.3,4 Diabetic ocular motor palsies, which typically occur as a unilateral mononeuropathy, may be the presenting sign of DM. Patients often experience pain, and recurrent paresis either ipsi or contralateral may occur. Occasionally, patients may have multiple unilateral or bilateral palsies simultaneously,3 as seen in 2 of our patients. A Mayo Clinic study,4 of over 4000 patients with ocular motor cranial nerves palsy of any etiology showed that the sixth cranial nerve was the most frequently involved (44%), followed by the third (28%), and the fourth nerve (15%). Like our report, several previous reports,2,3 showed that the third and the sixth cranial nerves were consistently more frequently affected than the fourth. This phenomenon may not be unique to diabetic ophthalmoplegia.1,2 Some studies3,4 showed that the diabetic ophthalmoplegia occurred more frequently in DM type 2 than in type one, which is similar to our findings. In our report, type 2 DM patients with oculomotor cranial neuropathies have a significantly higher prevalence of diabetic retinopathy, such as earlier reported.3,4 However, recently, Acaroglu et al,5 reported that the presence, and level of diabetic retinopathy are Brief Communication