Palinopsia and perilesional hyperperfusion following subcortical hemorrhage

Abnormal Connectivity and Brain Structure in Patients With Visual Snow

Objective

Visual snow (VS) is a distressing, life-impacting condition with persistent visual phenomena. VS patients show cerebral hypermetabolism within the visual cortex, resulting in altered neuronal excitability. We hypothesized to see disease-dependent alterations in functional connectivity and gray matter volume (GMV) in regions associated with visual perception.

Methods

Nineteen patients with VS and 16 sex- and age-matched controls were recruited. Functional magnetic resonance imaging (fMRI) was applied to examine resting-state functional connectivity (rsFC). Volume changes were assessed by means of voxel-based morphometry (VBM). Finally, we assessed associations between MRI indices and clinical parameters.

Results

Patients with VS showed hyperconnectivity between extrastriate visual and inferior temporal brain regions and also between prefrontal and parietal (angular cortex) brain regions (p < 0.05, corrected for age and migraine occurrence). In addition, patients showed increased GMV in the right lingual gyrus (p < 0.05 corrected). Symptom duration positively correlated with GMV in both lingual gyri (p < 0.01 corrected).

Conclusion

This study found VS to be associated with both functional and structural changes in the early and higher visual cortex, as well as the temporal cortex. These brain regions are involved in visual processing, memory, spatial attention, and cognitive control. We conclude that VS is not just confined to the visual system and that both functional and structural changes arise in VS patients, be it as an epiphenomenon or a direct contributor to the pathomechanism of VS. These in vivo neuroimaging biomarkers may hold potential as objective outcome measures of this so far purely subjective condition.

Structural and functional footprint of visual snow syndrome

Patients with visual snow syndrome suffer from a continuous pan-field visual disturbance, additional visual symptoms, tinnitus, and non-perceptional symptoms. The pathophysiology of visual symptoms might involve dysfunctional visual cortex. So far, the extra-visual system has not been investigated. We aimed at identifying structural and functional correlates for visual and non-visual symptoms in visual snow syndrome. Patients were compared to age- and sex-matched controls using ¹⁸F-2-fluoro-2-deoxy-d-glucose PET (n = 20 per group) and voxel-based morphometry (n = 17 per group). Guided by the PET results, region of interest analysis was done in voxel-based morphometry to identify structural-functional correspondence. Grey matter volume was assessed globally. Patients had corresponding hypermetabolism and cortical volume increase in the extrastriate visual cortex at the junction of the right lingual and fusiform gyrus. There was hypometabolism in the right superior temporal gyrus and the left inferior parietal lobule. Patients had grey matter volume increases in the temporal and limbic lobes and decrease in the superior temporal gyrus. The corresponding structural and functional alterations emphasize the relevance of the visual association cortex for visual snow syndrome. The broad structural and functional footprint, however, confirms the clinical impression that the disorder extends beyond the visual system.

[A case of various illusion, and hallucination caused by occipital lobe infarction]

A 70-year-old right-handed man noticed that the right side of the screen on his television displayed a time lag compared to the other side. For five days before admission, he had characteristic polyopia, visual photopia, and complex hallucination. Upon neurological examination, he showed no abnormal findings except for right homonymous hemianopia. MRI showed acute infarction of the occipital gyri and part of the lingual gyrus in the left occipital lobe. After admission, he experienced various visual hallucinations and visual illusions, including metamorphopsia and micropia, many times. They gradually disappeared after 2 months. Various hallucination was caused by the release of visual information, and illusion was thought to be due to integration failure of visual information. The appearance of complex hallucination in the blind visual field is known due to the damage of the region on the left occipital gyrus. However, the cases with various symptoms such as visual photopia and micropsia are rare.

Safety of topiramate for treating migraines

INTRODUCTION

Migraine is a very common medical disorder characterized by attacks of moderate-severe headache, nausea and disability. Topiramate is an effective, popular prophylactic migraine treatment, which is approved for use in adults and adolescents. Due to its multiple mechanisms of action, topiramate has multiple potential safety issues, including systemic and CNS adverse events, which may complicate therapy.

AREAS COVERED

This review evaluates common adverse events as seen in the pivotal trials of topiramate for migraine as well as those observed in postmarketing studies. These include weight loss, metabolic acidosis, renal calculi, acute angle closure glaucoma, visual distortions and cognitive slowing. Topiramate use during pregnancy is associated with an increased risk of cleft lip. This review highlights both common and unusual safety issues associated with topiramate use, including important drug interactions and a comparison with other migraine prophylactic agents.

EXPERT OPINION

Topiramate is highly effective in migraine prophylaxis but clinicians using the drug need to be aware of the potential for bothersome or serious adverse events. When treating with topiramate, use a slow titration to the goal dose of 100 mg or the lowest dose, which helps prevent migraine.

Measuring palinopsia: characteristics of a persevering visual sensation from cerebral pathology

Palinopsia is an abnormal perseverative visual phenomenon, whose relation to normal afterimages is unknown. We measured palinoptic positive visual afterimages in a patient with a cerebral lesion. Positive afterimages were confined to the left inferior quadrant, which allowed a comparison between afterimages in the intact and the affected part of his visual field. Results showed that negative afterimages in the affected quadrant were no different from those in the unaffected quadrant. The positive afterimage in his affected field, however, differed both qualitatively and quantitatively from normal afterimages, being weaker but much more persistent, and displaced from the location of the inducing stimulus. These findings reveal distinctions between pathological afterimages of cerebral origin and physiological afterimages of retinal origin.

[The medial temporal area and parietal lobe are involved in epileptic polyopia and palinopsia: A case report]

This report presents the case of an 83-year-old female with a tumor in the right temporal lobe. She experienced various epileptic visual auras including visual perseveration. Visual perseveration is classified into polyopia and palinopsia. Epileptic visual perseveration is a rare phenomenon, and the mechanism has not been fully explained. MRI revealed a tumor in the right temporal lobe with edema in the occipital white matter. To reveal mechanisms of epileptic polyopia and palinopsia, we recorded EEG and (123)I-IMP-SPECT when she experienced epileptic attacks. EEG showed epileptic discharges beginning at the occipital area, which spread to the temporal and parietal areas. During the EEG recording, the main symptom was an unformed hallucination. SPECT showed that blood flow increased in the right medial temporal and parietal lobes and, to a slightly lesser extent, in the right occipito-temporal area when the polyopia and palinopsia frequently appeared. Involvement of the multiple foci may have caused the different kinds of visual symptoms. The medial temporal and parietal areas were likely responsible for polyopia and palinopsia at least for this patient.

Palinopsia in patients with migraine: A case-control study

Objectives: This study was aimed at investigating the frequency of the visual phenomenon of palinopsia (visual perseveration) in patients with migraine.

Methods: We interviewed 63 patients with migraine with aura (MwA), 137 patients with migraine without aura (MwoA) and 226 sex-age-matched healthy control subjects using an ad hoc structured interview/questionnaire. The interview was divided into four classes of variables for statistical testing.

Results: Palinopsia occurred in 19/200 patients (9.5%); of them 10/63 had MwA and 9/137 MwoA (14.2% vs 6.6%, chi = 9.7, degrees of freedom = 1, p = 0.002). Patients with palinopsia had a significantly lower migraine attack frequency than those without this visual phenomenon (4.3 ± 0.3 vs 14.4 ± 0.2, z = 7.1, p < 0.0001). No healthy control subjects complained of palinopsia according to the structured interview/questionnaire.

Discussion: Palinopsia is probably under-diagnosed in patients with migraine. Further investigations are needed to assess whether migraineurs are particularly susceptible to the development of recurrent episodes of visual perseveration.

Palinopsia from a posteriorly placed glioma--an insight into its possible causes

Palinopsia is a distortion of processing in the visual system in which images persist or recur after the visual stimulus has been removed. It is a dysfunction of the association areas at the junction of temporal, occipital and parietal lobes and can be triggered by any lesion or dysfunction in this region. Here, the authors report the case of a patient with a glioma involving this region of the brain, who presented with palinopsia that subsequently disappeared once the tumour was surgically debulked. In the few cases of palinopsia that have been published so far, no such case has ever been reported. Furthermore, we took an insight into this rare and elusive phenomenon's causes and suggested Bayesian inference as a possible cause. The authors also mentioned visual evoked potentials as a useful test to be considered in future palinoptic patients.