Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus.

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability.

Phenotypical characteristics of idiopathic infantile nystagmus with and without mutations in FRMD7.

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.

Extended slow phase in latent/manifest latent nystagmus.

PURPOSE: To investigate the slow phase in latent/manifest latent nystagmus (LMLN) by producing long eye-drift intervals devoid of fast phases (extended slow phases [ESPs]) and to relate ESP metrics to clinical findings. METHODS: Ten patients with LMLN had eye movements recorded while attending to paired visual and auditory cues presented to their left or right. Patients compared location of the visual target with that of the subsequently heard tone. The auditory cue and the comparison task directed attention away from vision and delayed the fast-phase onset to obtain ESPs. ESP metrics were analyzed with regard to patients' clinical characteristics. Five patients' data were further explored by isolating slow-phase components. RESULTS: All patients exhibited ESPs that resembled the usual slow phase but lasted two to three times longer. Five patients maintained alignment, whereas the other five made vergence movements. Greater eye velocity, excursion, and convergence during an ESP were associated with poor vision and large uncorrected esotropia. These metrics decreased when the viewing eye was in adduction, compared with primary position or abduction. Slow-phase components found in five patients consisted of a dominant decreasing-velocity or linear drift and a low-amplitude periodic oscillation. CONCLUSIONS: Shifting attention away from vision reliably delays the fast phase, revealing long intervals of slow phase, which can facilitate nystagmus investigation. ESP analysis in five patients with LMLN demonstrated two slow-phase components. ESP characteristics suggest that better ocular alignment is associated with improved stability in LMLN and provide metrics of eye drift that correlate with vision.

A comparative demographicand socioeconomic study of spasmus nutans and infantile nystagmus.

PURPOSE: To compare the demographic and socioeconomic background of patients with spasmus nutans (SN) and patients with idiopathic infantile nystagmus (IIN). METHODS: This study was performed according to an observational case-control design. Parents or guardians of 23 patients with SN and 24 patients with IIN completed a 28-point questionnaire on demographic, socioeconomic, behavioral, personal, and family history. Mann-Whitney U tests were used to compare continuous dependents and chi(2) analyses for categorical variables. Correlation between variables was calculated by Spearman rho tests and odds ratios for SN by Mantel-Haenszel estimates. RESULTS: Comparing SN and IIN, Afro-American, and Hispanic ethnicity was significantly more common in SN (14 patients, 61%) than in IIN (1 patient, 4%). Significant differences between the groups were also found for gestational age (mean SN: 37.7 weeks, IIN: 40.3 weeks), home luminance at birth was reported to be brighter in more IIN patients (22 patients, 96%) as compared with the SN patients (15 patients, 71%). Factors reflecting a lower socioeconomic status were more prevalent in SN patients (annual household income, individual financially responsible for the household, source of income, availability of private medical insurance). In the SN group there were fewer married parents living together (9 families, 39%) than in the IIN group (21 families, 88%). Psychiatric disorders, including alcohol and drug abuse, were more frequent among parents of SN (10 parents, 47%) than of IIN (none). Annual household income and ethnicity correlated significantly with number of rooms/household. CONCLUSION: This study demonstrated differences between SN and IIN patients and their families with regard to socioeconomic status, ethnicity, gestational age, psychiatric diseases of parents, and parental estimation of light exposure early in life. We conclude that low socioeconomic status represents a risk factor for the development of SN.

Unilateral acquired upper eyelid ptosis and decreasing nystagmus.

PURPOSE: To describe a patient with congenital nystagmus that decreased in one eye after the development of a cavernous sinus meningioma. DESIGN: Interventional case report. METHODS: A 45-year-old man with congenital nystagmus, albinism, and high myopia presented with right upper eyelid ptosis that was corrected surgically on three occasions during a 3-year period. An episode of syncope was followed by diagnostic evaluation that disclosed a cavernous sinus meningioma. He commented that his right eye nystagmus progressively decreased. He was found to have ophthalmoplegia on the right eye due to nerve compression by the meningioma. RESULTS: A magnetic resonance imaging scan disclosed a cavernous sinus meningioma extending into the parachiasmal and clival areas. A biopsy specimen of the lesion demonstrated a meningioma. CONCLUSIONS: Any patient with acquired ptosis should have a complete ophthalmic examination, including evaluation of extraocular motility.

Single-stage adjustable strabismus surgery for restrictive strabismus.

PURPOSE: To evaluate the feasibility and stability of ocular alignment of single-stage adjustable strabismus surgery (SSASS) in restrictive strabismus. METHODS: This was an observational case series comprising 12 patients with restrictive strabismus (mean age, 54.8 years) who were treated with SSASS using intravenous midazolam, fentanyl, and topical anesthesia. All were studied in a retrospective institutional manner. The refractive strabismus in 7 patients was caused by dysthyroid orbitopathy. Five patients had undergone previous ocular surgery, and 4 had undergone previous strabismus surgery. SSASS typically involved the vertical rectus muscles. Horizontal rectus muscles were adjusted when necessary. Silicon-treated polyester suture material (Ti-cron; United States Surgical, Norwalk, CT no longer available), 6-0, were used for inferior rectus recessions. Ocular alignment was set at ortho at the end of surgery and evaluated at 2 days, 6 weeks, and 3 months after surgery. The typical hang-back procedure was to lock the suture at the middle and edges of the tendon or muscle at the intended disinsertion point. The tendon was then disinserted and hung back from the original insertion with adjustments until the desired position (ortho) and single vision were attained. RESULTS: All patients remained comfortable throughout surgery and had no significant postoperative discomfort. All patients except 2 (16.6%) maintained satisfactory vertical alignment (<2 prism diopters). These 2 patients with dysthyroid orbitopathy had progressive overcorrection after inferior rectus recession. CONCLUSIONS: SSASS, using intravenous midazolam, fentanyl, and topical anesthesia, is a safe and precise alternative treatment for patients with restrictive strabismus including those with dysthyroid orbitopathy.

Migrainous visual auras: a life history.

We document, as an autobiographical case report, a 72-year history of migraine and its changing nature. Minor neurological events have waxed and waned, causing repeated searches for pathology, but instead reconfirming an intact central nervous system. In this case it appears that visual migraine auras do not reflect severity of pathology. Visual auras of migraine are cyclical in frequency and intensity and may have remissions as long as 15 years.

Surgical treatment of trauma-induced periodic alternating nystagmus.

PURPOSE: To report a new treatment for acquired periodic alternating nystagmus in which medical therapy with baclofen was not tolerated. DESIGN: Interventional case report and literature review. INTERVENTION: Simultaneous adjustable bilateral retroequatorial horizontal rectus muscle recessions. MAIN OUTCOME MEASURES: Ocular alignment and ocular motility recordings. RESULTS: A 30-year-old man had blurred vision after an emergency left temporal craniotomy for gunshot wounds. Ophthalmologic examination revealed periodic alternating nystagmus that was documented by an infrared electronystagmogram. Baclofen was started but was not tolerated. Bilateral lateral and medial retroequatorial rectus muscle recessions were performed and were successful in the treatment of this patient. CONCLUSION: Simultaneous bilateral retroequatorial horizontal rectus recessions may be an effective treatment for intractable acquired periodic alternating nystagmus.