Bilateral lateral rectus palsies in high altitude illness.

A 50-year-old man with high altitude illness had bilateral lateral rectus palsies when he went to the Himalaya at 5,000 meters. He had no other neurological signs, except headache. He received acetazolamide, prednisone, and spent time in a hyperbaric chamber; but unfortunately he showed no improvement. Two months later, his diplopia completely resolved itself without any treatment, after his descent to a lower altitude.

Orbital pseudotumor: clinical features and outcomes.

To describe the clinical characteristics of orbital pseudotumor, a retrospective analysis was performed on patients with orbital pseudotumor at Siriraj Hospital for ten years. Forty-nine patients (24 males and 25 females; 62 eyes) with a mean age of 43.75 years were included (a mean follow-up of 25 months). Thirty-six patients (73.5%) had unilateral disease. The clinical features were proptosis (79.6%), ocular motor deficit (61.2%), pain (51%), lid swelling or lid mass (44.9%), ptosis (24.5%), and chemosis (18.4%). The most common presenting sign was proptosis (49%). All were treated with corticosteroids with clinical improvement in 40 (81.6%) patients. Ten (83.3%) of 12 patients with visual loss improved with mean recovery time of 10.3 days. Ocular motility recovered in 24 (80%) patients, occurring an average of 17.8 days after initiation of therapy. It is concluded that the clinical features of orbital pseudotumor are varied. Most patients were improved with corticosteroids treatment.

Factors associated with insensitivity to pyridostigmine therapy in Thai patients with ocular myasthenia gravis.

The objective of this study was to determine factors associated with pyridostigmine therapy in patients with ocular myasthenia gravis (OMG). This retrospective study included eighty-five patients with OMG who have been treated with pyridostigmine. Patients were excluded if they were diagnosed as generalized myasthenia gravis within a month after diagnosis or were treated with other medications. Forty-two patients responded to pyridostigmine and 43 patients did not. There were no significant differences in gender, age, the duration of symptoms before treatment, the dosage of pyridostigmine, and the initial presentations of ptosis or diplopia between the two groups. However, an initial presentation of concurrent ptosis and diplopia and the presence of systemic involvement after follow up were significant factors associated with an insensitivity to pyridostigmine in patients with OMG (p = 0.001 and p = 0.01, respectively). Determining these factors could help predict the pyridostigmine response in patients with OMG.

A comparative study of visual evoked potentials in optic neuritis and optic neuritis with multiple sclerosis.

OBJECTIVE: To compare the visual evoked potentials (VEP) in patients with acute optic neuritis, recurrent optic neuritis, and optic neuritis with multiple sclerosis. MATERIAL AND METHOD: The authors retrospectively reviewed VEP latency records of the patients with optic neuritis in Siriraj Hospital from 1995 to 2005 and divided them into three groups, acute optic neuritis, recurrent optic neuritis, and optic neuritis with multiple sclerosis (ON/MS). The patients with non-recordable VEP in the analysis were excluded. Comparison of the mean latency of the VEP in affected eyes among the three groups was statistically analyzed by a nonparametric independent sample test. RESULTS: Twenty-two patients with acute optic neuritis, 8 patients with recurrent optic neuritis, and 22 patients with ON/MS participated in this study. The mean age among the three groups was not statistically significant. The median value of the latency of flash VEP (fVEP) and pattern reversal VEP (PRVEP) in the acute optic neuritis group was shorter than that of the recurrent optic neuritis group, and statistically significant (fVEP p = 0.012; PRVEP, p = 0.004). The median value of the latency of PRVEP in the acute optic neuritis group was shorter than that of the ON/MS group, and statistically significant (PRVEP p = 0.002). The median value of the latency of both fVEP and PRVEP in the recurrent optic neuritis group and ON/MS group were delayed with no statistical significance (fVEP p = 0.458; PRVEP, p = 0.403). CONCLUSION: The VEP can be used to demonstrate the demyelinating mechanism of optic neuritis and optic neuritis with multiple sclerosis, but cannot determine the susceptibility of the patients with acute ON to become MS. The significantly delayed latency of VEP in recurrent optic neuritis is possibly caused by severe damage of the optic nerve conduction from recurrent attacks.

Case report: A Thai patient with Leber's hereditary optic neuropathy linked to mitochondrial DNA 14484 mutation.

A young Thai male presented with bilateral visual loss and disc pallor. The 14484 mutation responsible for Leber's hereditary optic neuropathy (LHON) was identified on blood mitochondrial analysis. His visual loss was more severe than the visual loss described in Caucasian and Japanese patients and showed no improvement. He had no other identifiable mutations related to LHON nor any associated neurological disorder. This is the first case report of LHON with the 14484 mutation in a Thai patient.

Botulinum toxin treatment for upper lid retraction of dysthyroidism.

Six patients with upper eyelid retraction due to dysthyroidism at Siriraj Hospital received subcutaneous botulinum toxin treatment at a dosage of 5-20 units per injection. Five patients experienced an improvement in the lid retraction lasting at least 40 months and 3 patients required more than one injection. Botulinum toxin injection is an alternative treatment for the upper eyelid retraction of dysthyroidism, which is effective and causes minimal side effects, particularly in patients with euthyroid status.

Optic neuritis: characteristics and visual outcome.

OBJECTIVE: To determine clinical characteristics of patients with optic neuritis and visual outcome after intravenous methylprednisolone treatment. METHOD: A total of 81 patients with optic neuritis were reviewed retrospectively with regard to their clinical characteristics by dividing into two groups as follows: group I had isolated optic neuritis and group II had optic neuritis with demyelinative disease. The visual outcome in these patients before and after intravenous methylprednisolone treatment was analyzed. RESULTS: Of 81 patients with optic neuritis, 63 patients (77.8%) had isolated optic neuritis and 18 (22.2%) patients were optic neuritis with demyelinative disease. The ages of the patients ranged from 16 to 59 years (mean = 35.3 years) in patients with isolated optic neuritis and from 16 to 73 years of age (mean = 35.8 years) in patients with optic neuritis with demyelinative disease. After treatment, 45 patients (52 eyes) with isolated optic neuritis and 14 patients (25 eyes) with optic neuritis with demyelinative disease who were followed-up for more than 10 days were studied. After treatment, 60 per cent of the isolated optic neuritis patients and 24 per cent of the optic neuritis patients with demyelinative disease had a visual acuity of 6/12 or better respectively. The isolated optic neuritis who had an onset interval to treatment of less than 8 days had a visual acuity better than 6/9 in 75 per cent. CONCLUSION: The final visual outcome in patients with isolated optic neuritis who received earlier treatment was better than those who received treatment later.

A prospective randomized trial of megadose methylprednisolone and high dose dexamethasone for traumatic optic neuropathy.

PURPOSE: To determine whether the improvement in visual acuity obtained when using high dose dexamethasone in the treatment of traumatic optic neuropathy was comparable to that of megadose methylprednisolone. METHOD: A total of forty-four patients with traumatic optic neuropathy were prospectively randomized and selected to receive intravenous high dose dexamethasone or megadose methylprednisolone within 2 weeks of injury. Age, gender, cause of injury, interval from injury to treatment, initial, post-pulse, and final visual acuity were analysed statistically to compare the dexamethasone and methylprednisolone groups. RESULTS: The mean interval to treatment was not significantly different (p=0.28) for the dexamethasone group at 5.5 days compared to the methylprednisolone group at 4.1 days. Visual improvement of at least two lines of the Snellen chart or two levels of unmeasured visual acuity was shown in 9 patients (37.5%) of the dexamethasone group and 10 patients (50%) of the methylprednisolone group. There was no statistically significant difference between the initial and post-pulse visual acuity (p=1.0) and the initial and final visual outcome (p=0.60) in the dexamethasone group compared with the methylprednisolone group. CONCLUSION: There was no significant difference in the visual acuity obtained after treatment with intravenous dexamethasone or methylprednisolone for traumatic optic neuropathy.

Comparative study of edrophonium test and neostgmine test in ocular myasthenia gravis.

To compare the sensitivity of edrophonium test and neostigmine test in ocular myasthenia. Materials and methods: the edrophonium and neostimine tests in 57 consecutive patients who presented with symptoms of ptosis and/or binocular diplopia upon exertion were studied prospectively in Neuroophthalmologic Unit, Siriraj Hospital. The palpebral fissure, marginal reflex distance (MRD), levator palpebare superioris muscle function and angle of deviation by Prism and cover test were measured before and after performing the tests for evaluation of positive result of the edrophonium and neostigmine tests. All patients were treated with pyridostigmine for one week. The patients who responded to the treatment were diagnosed as ocular myasthenia gravis. Statistical analysis was carried out by the Chi-square test. Results: Forty-five patients were diagnosed as ocular myasthenia gravis and 12 patients were nonmyasthenic group. The edrophonium test was positive in 44 patients (97.8%) and the neostigmine test was positive in 38 patients (84.4%) in myasthenic group. In nonmyasthenic group, 12 patients (100%) were found negative in both tests. Edrophonium produced more severe side effects than neostigmine. Conclusion: The neostigmine test displayed similar positive result compared with the edrophonium test but is safer and easier to perform.

Mitochondrial genetics of mitochondrial diseases in Thailand.

Mitochondrial diseases are a heterogenous group of disorders with various biochemical defects in the oxidative phosphorylation system. They are included in the differential diagnosis of many cases of multisystem disease even though the neuromuscular and central nervous system are mainly involved. The complexity of the disease can make it difficult for the clinician to diagnose. The number of the patients suffered from Mitochondrial disease is expected to be increasingly found each year. We present here the mitochondrial diseases with their underlying molecular genetics in the mitochondrial DNA found in Thai patients.

Retinal arterial obstruction: The etiology and visual result.

A series of 17 consecutive patients with central retinal artery obstruction (CRAO; 15 patients, 16 eyes) and branch retinal arterial obstruction (BRAO, two patients) were studied at Siriraj Hospital between January 1994 and June 1997 with respect to cause, associated factors and visual result. The study group compressed 13 men and four women with a mean age of 48 years. Hyperlipidemia was the most common underlying disorder in those patients aged less than 45 years. Retinal emboli and increased intraocular pressure were identified as the ocular in three patients. The visual result improved in four patients, two each of whom had interval times from onset to treatment of less than six hours and more than 48 hours. No light perception vision at the initial examination occurred in 3 patients and none had improved vision.