RESUMO
Idiopathic infantile nystagmus (IIN) consists of involuntary oscillations of the eyes. The familial form is most commonly X-linked. We recently found mutations in a novel gene FRMD7 (Xq26.2), which provided an opportunity to investigate a genetically defined and homogeneous group of patients with nystagmus. We compared clinical features and eye movement recordings of 90 subjects with mutation in the gene (FRMD7 group) to 48 subjects without mutations but with clinical IIN (non-FRMD7 group). Fifty-eight female obligate carriers of the mutation were also investigated. The median visual acuity (VA) was 0.2 logMAR (Snellen equivalent 6/9) in both groups and most patients had good stereopsis. The prevalence of strabismus was also similar (FRMD7: 7.8%, non-FRMD7: 10%). The presence of anomalous head posture (AHP) was significantly higher in the non-FRMD7 group (P < 0.0001). The amplitude of nystagmus was more strongly dependent on the direction of gaze in the FRMD7 group being lower at primary position (P < 0.0001), compared to non-FRMD7 group (P = 0.83). Pendular nystagmus waveforms were also more frequent in the FRMD7 group (P = 0.003). Fifty-three percent of the obligate female carriers of an FRMD7 mutation were clinically affected. The VA's in affected females were slightly better compared to affected males (P = 0.014). Subnormal optokinetic responses were found in a subgroup of obligate unaffected carriers, which may be interpreted as a sub-clinical manifestation. FRMD7 is a major cause of X-linked IIN. Most clinical and eye movement characteristics were similar in the FRMD7 group and non-FRMD7 group with most patients having good VA and stereopsis and low incidence of strabismus. Fewer patients in the FRMD7 group had AHPs, their amplitude of nystagmus being lower in primary position. Our findings are helpful in the clinical identification of IIN and genetic counselling of nystagmus patients.
Assuntos
Proteínas do Citoesqueleto/genética , Oftalmopatias Hereditárias/genética , Proteínas de Membrana/genética , Mutação , Nistagmo Patológico/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Cromossomos Humanos X/genética , Percepção de Cores , Percepção de Profundidade , Oftalmopatias Hereditárias/fisiopatologia , Oftalmopatias Hereditárias/psicologia , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças Genéticas Ligadas ao Cromossomo X/fisiopatologia , Doenças Genéticas Ligadas ao Cromossomo X/psicologia , Cabeça/patologia , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Nistagmo Congênito/genética , Nistagmo Congênito/fisiopatologia , Nistagmo Congênito/psicologia , Nistagmo Patológico/fisiopatologia , Nistagmo Patológico/psicologia , Linhagem , Postura , Estrabismo/genética , Acuidade VisualRESUMO
PURPOSE: The effect of aging on torsional optokinetic nystagmus (tOKN) is unknown. The authors investigated changes in tOKN associated with aging in a group of healthy subjects. METHODS: Monocular torsional eye movements were recorded from 30 subjects between 19 and 72 years of age. Constant-velocity rotary stimuli in clockwise and counterclockwise directions were used to elicit tOKN at 40 degrees /s and 400 degrees /s. RESULTS: The number of subjects in whom tOKN could not be detected increased with age and was consistent in both directions of stimulation and at both angular velocities of stimulation. CONCLUSIONS: tOKN appears to fail increasingly with age, in contrast to previous reports of horizontal and vertical OKN systems. This indicates that the ability to respond to rotary motion is more sensitive to the effects of aging.
Assuntos
Envelhecimento/fisiologia , Nistagmo Optocinético/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Torção MecânicaRESUMO
We describe a novel treatment of superior oblique myokymia. A 40-year-old woman was treated with gabapentin for this disorder with partial success and reported significant side effects including loss of libido and weight gain. After a drug holiday, memantine therapy was initiated resulting in a substantial improvement in her symptoms with far fewer side effects and stability on long-term maintenance therapy.