Browsing by Author "Lemos, J"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Downbeat nystagmus elicited by eyelid closurePublication . Lemos, J; Pereira, D; Amorim, M; Santiago, B; Paiva, A; Cunha, LWe describe a patient with downbeat nystagmus (DBN) evoked only by eye closure. Brain and spinal cord magnetic resonance imaging revealed a T2 paramedian lesion in the left lower basis pontis and other white matter lesions consistent with multiple sclerosis. One potential mechanism for DBN in this case involves transverse ephaptic spread of excitation from areas that subserve coordinated lid closure to the decussating ventral tegmental tract.
- Ocular neuromyotoniaPublication . Soares-Dos-Reis, R; Martins, AI; Brás, A; Matos, A; Bento, C; Lemos, JOcular neuromyotonia is a rare, albeit treatable, ocular motor disorder, characterised by recurrent brief episodes of diplopia due to tonic extraocular muscle contraction. Ephaptic transmission in a chronically damaged ocular motor nerve is the possible underlying mechanism. It usually improves with carbamazepine. A 53-year-old woman presented with a 4-month history of recurrent episodes of binocular vertical diplopia (up to 40/day), either spontaneously or after sustained downward gaze. Between episodes she had a mild left fourth nerve palsy. Sustained downward gaze consistently triggered downward left eye tonic deviation, lasting around 1 min. MR scan of the brain was normal. She improved on starting carbamazepine but developed a rash that necessitated stopping the drug. Switching to lacosamide controlled her symptoms.
- Prognosis of Ocular Myasthenia Gravis: Retrospective Multicenter AnalysisPublication . Nagia, L; Lemos, J; Abusamra, K; Cornblath, WT; Eggenberger, ERPURPOSE: To calculate the rate and timing of conversion from ocular myasthenia gravis to generalized myasthenia gravis. DESIGN: Retrospective multicenter analysis. SUBJECTS: Patients included in the study were diagnosed with ocular myasthenia gravis without the presence of generalized disease at onset. METHODS: We conducted a retrospective multicenter analysis. We reviewed charts of 158 patients who met diagnostic criteria for ocular myasthenia gravis. Patients were divided into 2 subgroups: an immunosuppressant treatment group and a nonimmunosuppressant treatment group. Timing of conversion to generalized disease and duration of follow-up also was evaluated. Additional data such as clinical symptoms at presentation, laboratory test results, and chest imaging results also were recorded. MAIN OUTCOME MEASURES: Conversion rates to generalized myasthenia at 2 years, effect of immunosuppression on conversion, and timing of conversion. RESULTS: The 158-patient cohort included 76 patients who received immunosuppressant therapy; the remaining 82 patients did not. The overall conversion rate to generalized disease was 20.9%. At 2 years, generalized myasthenia developed in 8 of 76 patients in the treated group and in 15 of 82 patients in the nonimmunotherapy group (odds ratio, 0.52; 95% confidence interval, 0.20-1.32). Median time for conversion to generalized disease was 20 months in the nonimmunosuppressant group and 24 months in the immunosuppressant group. Conversion occurred after 2 years of symptom onset in 30% of patients. CONCLUSIONS: Conversion rates from ocular to generalized myasthenia gravis may be lower than previously reported both in immunosuppressed and nonimmunosuppressed patients. A subset of patients may continue to convert to generalized disease beyond 2 years from onset of symptoms, and close monitoring should be continued.
- Visual and ocular motor function in the atypical form of neurodegeneration with brain iron accumulation type IPublication . Jesus-Ribeiro, J; Farinha, C; Amorim, M; Matos, A; Reis, A; Lemos, J; Castelo-Branco, M; Januário, CBACKGROUND/AIMS: Neurodegeneration with brain iron accumulation (NBIA) type I is a rare disease that can be divided into a classical or atypical variant, according to age of onset and clinical pattern. Neuro-ophthalmological involvement has been documented in the classical variant but only anecdotically in the atypical variant. We sought to describe the visual and ocular motor function in patients with atypical form of NBIA type I. METHODS: Cross-sectional study, including patients with genetically confirmed NBIA type I and classified as atypical variant, who underwent ophthalmological examination with best corrected visual acuity (BCVA), optical coherence tomography (OCT), fundus autofluorescence (FAF), electroretinography (ERG), visual evoked potentials (VEP) and video-oculography. RESULTS: Seven patients with a mean BCVA of 0.12±0.14 logMAR were included. Only two patients showed structural evidence of advanced retinopathy in OCT and FAF, and there were no cases of optic atrophy. ERG data, however, showed abnormal scotopic and/or photopic responses in all patients. VEP were normal in all three patients. Ocular fixation was markedly unstable (eg, increased rate of saccadic pulses) in the majority of patients (5). Additional mild ocular motor disturbances included low gain pursuit (2), hypermetric saccades (1), low gain optokinetic (2) and caloric and rotatory responses (3). CONCLUSION: Functional retinal changes associated with marked instability of ocular fixation should be included in the clinical spectrum of NBIA, particularly in the atypical form.
- Visual Cortex Plasticity Following Peripheral Damage To The Visual System: fMRI EvidencePublication . Lemos, J; Pereira, D; Castelo-Branco, MOver the last two decades, functional magnetic resonance imaging (fMRI) has become a powerful research method to investigate cortical visual plasticity. Abnormal fMRI response patterns have been occasionally detected in the visually deprived cortex of patients with bilateral retinal diseases. Controversy remains whether these observations indicate structural reorganization of the visual cortex or unmasking of previously silent cortico-cortical connections. In optic nerve diseases, there is weak evidence showing that early visual cortex seems to lack reorganization, while higher-order visual areas undergo plastic changes which may contribute to optimise visual function. There is however accumulating imaging evidence demonstrating trans-synaptic degeneration of the visual cortex in patients with disease of the anterior visual pathways. This may preclude the use of restorative treatments in these patients. Here, we review and update the body of fMRI evidence on visual cortical plasticity.