Transient Retinal Dysfunctions after Acute Cannabis Use.

Although cannabis is very widespread worldwide, the impact of cannabis on visual function remains poorly understood. This is partly due to numerous difficulties met in developing clinical studies in cannabis users. Here, we report the first documented case of neuroretinal dysfunction after acute cannabis smoking. This observation was favored by the need of an annual ophthalmic evaluation in the context of a chloroquine intake for a systemic lupus erythematosus in a 47-year-old heavy cannabis user. A complete ophthalmic evaluation including visual acuity tests, intraocular pressure, fundoscopic examination, automated 10° central visual field, full-field electroretinogram (ERG) and multifocal ERG was performed twice - 30 min and 5 h after cannabis smoking. A strong decrease (up to 48%) in the a-wave amplitude of the full-field ERG was measured 30 min after cannabis smoking for all scotopic responses compared with the responses 5 h after smoking. Other tests showed reproducible results between the 2 series of measurements. This clinical case suggests that acute inhalation of cannabis affects the photoreceptors functioning. This rare situation suggests further investigations are required on the impact of cannabis on retinal processing, especially since cannabis has been incriminated in car injuries.

Sulfonylurea Therapy Benefits Neurological and Psychomotor Functions in Patients With Neonatal Diabetes Owing to Potassium Channel Mutations.

OBJECTIVE: Neonatal diabetes secondary to mutations in potassium-channel subunits is a rare disease but constitutes a paradigm for personalized genetics-based medicine, as replacing the historical treatment with insulin injections with oral sulfonylurea (SU) therapy has been proven beneficial. SU receptors are widely expressed in the brain, and we therefore evaluated potential effects of SU on neurodevelopmental parameters, which are known to be unresponsive to insulin. RESEARCH DESIGN AND METHODS: We conducted a prospective single-center study. Nineteen patients (15 boys aged 0.1-18.5 years) were switched from insulin to SU therapy. MRI was performed at baseline. Before and 6 or 12 months after the switch, patients underwent quantitative neurological and developmental assessments and electrophysiological nerve and muscle testing. RESULTS: At baseline, hypotonia, deficiencies in gesture conception or realization, and attention disorders were common. SU improved HbA1c levels (median change -1.55% [range -3.8 to 0.1]; P < 0.0001), intelligence scores, hypotonia (in 12 of 15 patients), visual attention deficits (in 10 of 13 patients), gross and fine motor skills (in all patients younger than 4 years old), and gesture conception and realization (in 5 of 8 older patients). Electrophysiological muscle and nerve tests were normal. Cerebral MRI at baseline showed lesions in 12 patients, suggesting that the impairments were central in origin. CONCLUSIONS: SU therapy in neonatal diabetes secondary to mutations in potassium-channel subunits produces measurable improvements in neuropsychomotor impairments, which are greater in younger patients. An early genetic diagnosis should always be made, allowing for a rapid switch to SU.

The cannabinoid system and visual processing: a review on experimental findings and clinical presumptions.

Cannabis is one of the most prevalent drugs used worldwide. Regular cannabis use is associated with impairments in highly integrative cognitive functions such as memory, attention and executive functions. To date, the cerebral mechanisms of these deficits are still poorly understood. Studying the processing of visual information may offer an innovative and relevant approach to evaluate the cerebral impact of exogenous cannabinoids on the human brain. Furthermore, this knowledge is required to understand the impact of cannabis intake in everyday life, and especially in car drivers. Here we review the role of the endocannabinoids in the functioning of the visual system and the potential involvement of cannabis use in visual dysfunctions. This review describes the presence of the endocannabinoids in the critical stages of visual information processing, and their role in the modulation of visual neurotransmission and visual synaptic plasticity, thereby enabling them to alter the transmission of the visual signal. We also review several induced visual changes, together with experimental dysfunctions reported in cannabis users. In the discussion, we consider these results in relation to the existing literature. We argue for more involvement of public health research in the study of visual function in cannabis users, especially because cannabis use is implicated in driving impairments.

Vertical and horizontal smooth pursuit eye movements in children with developmental coordination disorder.

AIM: Our aim was to study horizontal and vertical smooth pursuit eye movements in children with developmental coordination disorder (DCD). METHOD: Horizontal and vertical smooth pursuit eye movements of 91 children were studied using electro-oculography: 27 children with DCD (23 males, four females), according to the DSM-IV-TR criteria, and 64 comparison children (26 males, 38 females). All children were 7 to 12 years old (mean 9y, SD 1.5y). Among the group of children with DCD, eight had received intervention. Intervention exercised static and dynamic fixation, saccades, visual strategies, visuospatial abilities, and eye-hand coordination. A smooth pursuit gain index was calculated and statistical comparisons were made between the two groups of children. RESULTS: Horizontal pursuit gain was similar in both populations, but vertical pursuit gain was significantly impaired (p<0.001, after adjusting for age as covariate), i.e. more saccadic in children with DCD (18-99%; n=27, mean 51.6%, median 48.5%, SD 23.2%) than in comparison participants (35-97%; n=63, mean 66.4%, median 65.0%, SD 15.4%). Among the DCD group, the vertical pursuit index was also significantly higher (p=0.009) in the intervention subgroup (29-99%; n=8, mean 69.4%, median 75.5%, SD 28.7%) than in the non-intervention subgroup (18-74%; n=19, mean 44.1%, median 42.5%, SD 15.9%). INTERPRETATION: These results suggest a delay in the maturation of the pursuit system in children with DCD.

Ocular manifestations of cobalamin C type methylmalonic aciduria with homocystinuria.

PURPOSE: To report the ocular complications of cobalamin-C type methylmalonic aciduria with homocystinuria (cblC) in a large consecutive series of patients. METHODS: Medical records of patients with genetically diagnosed cblC disease from Mount Sinai Medical Center, New York, and Hôpital Necker, Paris, France, were reviewed. All patients with the diagnosis of cblC seen after January 2008 at Mount Sinai and January 1998 at Hôpital Necker were included. RESULTS: A total of 9 cases are reported. Age at initial ocular examination ranged from 3.5 months to 10 years of age. All 9 patients had early-onset disease, with manifestation of disease presenting prior to 1 year of age. Two patients had definitive optic nerve pallor. All patients had retinal findings ranging from peripheral pigmentary retinal changes to central macular atrophy with Bull's eye lesions. Optical coherence tomography was performed on one child and showed retinal thinning in the area of the bull's eye lesions. Electroretinography was performed in 6 of the 9 patients, three of whom showed decreased scotopic and photopic responses. The other three patients had normal responses on electroretinography. CONCLUSIONS: Ocular findings in patients with cblC are variable. All patients in the study exhibited early-onset disease and had noteworthy ophthalmic findings. To the best of our knowledge, this is the first study in the literature correlating optical coherence tomography findings with fundus findings in cblC.

Asymptomatic atrophy of the temporal median raphe of the retina associated with cerebral vasculopathy in homozygous sickle cell disease.

A 13-year-old girl with homozygous sickle cell disease was referred for vision loss in her left eye of 1 year's duration. Clinical findings were consistent with a past retinal arterial occlusion. In the asymptomatic right eye, spectral domain optical coherence tomography showed a severe atrophy of the inner retinal layers of the temporal median raphe; a significant internal carotid stenosis was also present. We hypothesize that specific atrophy of the retinal temporal median raphe resulted from chronic ischemia. The inner layers of the retina are vascularized by terminal vessels and the median raphe can therefore be regarded as a junction territory; its atrophy may represent an ocular equivalent of a silent border zone cerebral infarct.

Accuracy and results of photopic flash electroretinogram performed with skin electrodes in infants.

PURPOSE: As it is not always possible to use corneal electrodes for recording electroretinograms (ERG) in children, it is necessary to check the feasibility of performing ERG with skin electrodes and to try to establish normative data. METHODS: Fifty-one healthy children (aged 7-11 years) were recruited. Cone ERG and 30-Hz flicker ERG were recorded with one active skin electrode positioned over the lower eyelid and a reference electrode at the outer canthus of the eye. Responses were recorded to full-field stimuli. Correlations between results of both eyes were studied. Results were compared to normative data obtained with corneal electrodes. RESULTS: Cone ERG response was obtained in 100/102 eyes. Flicker ERG was obtained in 88/102 eyes. No correlation between eyes was found for the a-wave latency, the a-wave amplitude, and the latency of the flicker. Mean b-wave implicit time of the cone ERG was 38.71 ± 1.6 ms; the median of its amplitude was 10.0 µV. The median of the amplitude of the flicker ERG was 12.55 µV. CONCLUSIONS: Amplitudes are significantly reduced, with a scaling factor of 8.75 for the b-wave amplitude of the cone ERG compared to corneal electrodes (9.6 for the a-wave amplitude and 8.87 for the flicker amplitude). Our study contributes to the establishment of normative data for skin electrode ERG. It emphasizes the feasibility and accuracy of this method. It is very useful to assess the normality of the ERG in many clinical situations, such as nystagmus and suspicion of delayed visual maturation.

Subtypes of developmental coordination disorder: research on their nature and etiology.

Children with Developmental Coordination Disorder (DCD) are a group embracing clumsiness and developmental dyspraxia. Our study provides a better understanding of the nature of DCD and its etiology, and identifies subtypes of dyspraxia. Forty-three children with DCD (5-15 years) were enrolled on the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV-TR]; American Psychiatric Association, 2000) criteria. Extensive standardized evaluations were conducted. We distinguished from two patterns of "pure" developmental dyspraxia: ideomotor and visual-spatial/visual-constructional, and mix dyspraxia with more co-morbidities. Our study provides a better understanding of the nature of DCD, and sheds light on its etiology and brain dysfunction, so as to identify subtypes of developmental DCD/dyspraxia with specific clinical criteria.

Vertical and horizontal smooth pursuit eye movements in children: a neuro-developmental study.

An evaluation of eye movements is very useful in neurological disorders but is complicated by issues such as maturation and lack of normative data in children. In order to address these issues we studied smooth pursuit eye movements of 65 normal children aged 7-11 years old. The gain of horizontal smooth pursuit (HSP) was higher than the gain of the vertical smooth pursuit (SP) and this difference had a statistical tendency to disappear with aging from 7 to 11 years. These data suggest that, in the cerebral regions involved in the control of SP, i.e. posterior parietal and superior temporal lobe regions, the networks for VSP mature latter than those for HSP.

Familial congenital oculomotor apraxia: clinical and electro-oculographic features.

The electro-oculographic (EOG) features of both horizontal and vertical eye movements in congenital oculomotor apraxia (COMA) were not previously reported. A girl referred to the ophthalmologic department for abnormal eye movements was diagnosed as COMA. The same abnormal ocular movements were observed in her younger sister and her father who was unaware of his difficulties to initiate voluntary saccades. When performed, EOG recordings of all horizontal and vertical saccadic eye movements were severely altered whatever the age of the patient. Pursuit was normal for these patients. It confirms that the control of saccadic eye movements is still altered in adults in both directions horizontal and vertical that were never reported. EOG is necessary to rule out inherited form of this saccade initiation failure.