Friday, October 29, 2021

Fixation-off sensitivity

Inspired by a patient

Wang X, Zhang Y, Zhang W, Shen C, Jin L, Chen B, Jiang Z, Tao JX, Liu Y. The electroclinical features of idiopathic generalized epilepsy patients presenting with fixation-off sensitivity. Epileptic Disord. 2018 Dec 1;20(6):479-489. doi: 10.1684/epd.2018.1021. PMID: 30530446.


To determine the electroclinical features of fixation-off sensitivity (FOS) in patients with idiopathic generalized epilepsy (IGE). We searched the EEG database using the terms "fixation-off sensitivity" and "idiopathic generalized epilepsy" over a four-year period from March 2014 to April 2018 in the Xijing Hospital, Xi'an, China. FOS was evaluated according to the technique proposed by Panayiotopoulos. Photic stimulation procedure and neuropsychological testing were performed during video-EEG monitoring. FOS was observed in eight patients with several different IGE syndromes, including four with eyelid myoclonia/Jeavons syndrome, two with juvenile myoclonic epilepsy, one with photosensitivity epilepsy, and one with epilepsy with generalized tonic-clonic seizures only. FOS was associated with seizures in five patients manifesting with eyelid myoclonic, myoclonic, and myoclonic-tonic-clonic seizures, and eyelid myoclonic status. FOS coexisted with photosensitivity in six patients as independent EEG features. Neuropsychological testing revealed transitory cognitive impairments associated with FOS. FOS is associated with several different IGE syndromes and may coexist with photosensitivity in the same patient as independent EEG features. FOS may be associated with both clinical seizures and cognitive impairments. Intermittent photic stimulation and registration of different eye conditions with and without fixation will aid the study of the dynamics of the visual system in epilepsy patients. [Published with video sequences on].

Das Pektezel L, Tezer FI, Saygi S. Electroclinical Presentations of Fixation-off Sensitivity in Adults With Symptomatic Epilepsy. J Clin Neurophysiol. 2021 Jul 6. doi: 10.1097/WNP.0000000000000880. Epub ahead of print. PMID: 34280943.


Purpose: Fixation-off sensitivity (FOS) is a discharge pattern on EEG that occurs owing to the loss of central vision or fixation. Knowledge regarding the relationship between FOS and symptomatic epilepsy is limited. Therefore, we aimed to evaluate the electroclinical features of FOS in adult patients with symptomatic epilepsy. 

Methods: Outpatient video-EEG records of the Hacettepe University Faculty of Medicine were reviewed from 2009 to 2019. Patients aged >18 years with symptomatic epilepsy with a FOS pattern were included. Demographic, clinical, EEG, and neuroimaging data were retrospectively evaluated from an electronic database and patient files. 

Results: Eight patients (50% female) were included in this study; seven (87%) had refractory epilepsy. Prominent risk factors were family history of epilepsy in five patients and prenatal/natal insult in four patients. Notable MRI signs included cortical developmental malformation, posterior gliosis, and frontoparietal porencephalic cyst. The FOS pattern was generalized with posterior emphasis in two patients and lateralized or localized in six patients: frontocentroparietal (n = 1) and temporoparietooccipital (n = 5). Fixation-off sensitivity discharges were found to be increased by hyperventilation and decreased by drowsiness and sleep in 50% of patients. Fixation-off sensitivity disappeared in one patient with good seizure control. 

Conclusions: In this study, the disappearance of FOS in an epileptic patient with a structural lesion and detection of FOS activity related to a frontoparietal porencephalic cyst were remarkable. Family history of epilepsy was also substantially high. Our results indicate that the underlying mechanism of FOS is much more complicated than previously thought.

Dede HÖ, Bebek N, Emekli S, Baykan B, Yapıcı Z, Gökyiğit A. The clinical significance and electrophysiologic findings of fixation-off and closure of the eyes sensitivity: Data from a prospective unselected population. Epilepsy Res. 2021 Feb;170:106541. doi: 10.1016/j.eplepsyres.2020.106541. Epub 2020 Dec 25. PMID: 33387799.


Purpose: Electroencephalography (EEG) findings related to the eye-closing motion can be defined in two ways: 'sensitivity to eyes closed' (SEC) and 'eye closure sensitivity (ECS).' Fixation-off sensitivity (FOS) is a different phenomenon induced by the elimination of central vision/fixation. The purpose of our study was to determine the frequencies of SEC, ESC, and FOS, and to analyze the relationship between eyes closure and the fixation-off phenomenon and clinical importance in an unselected population. 

Methods: We prospectively evaluated 200 routine interictal EEGs by adding a standardized FOS examination protocol between June and September 2015. Goggles covered with semitransparent tape were used to evaluate FOS. We determined SEC when the epileptiform discharges appeared during eye closure and continued during the eye closed state, whereas ECS was defined as transient epileptic abnormalities following the closure of the eyes lasting for 1-4 sec. The patients were evaluated in terms of demographic characteristics, clinical features, and the relationship between SEC, ECS, and FOS. 

Results: We detected SEC in 9 (4.4 %) and ECS in 11 (5.4 %) patients. FOS was detected in four (44.4 %) of the patients who showed SEC, all of whom had occipital epileptiform discharges. A statistically significant correlation was found between FOS and treatment resistance in the SEC group (p < 0.001). In logistic regression analysis, occipital lobe epilepsy (p < 0.001) and age under 20 years (p = 0.004) were found as risk factors for SEC. Another interesting finding was the suppression of epileptic discharges with fixation-off in three of 11 patients with ECS. 

Conclusions: According to the results of our study, FOS is related to treatment resistance. Therefore, FOS should be evaluated in patients with SEC.

Lo Barco T, Kaminska A, Solazzi R, Cancés C, Barcia G, Chemaly N, Fontana E, Desguerre I, Canafoglia L, Hachon Le Camus C, Losito E, Villard L, Eisermann M, Dalla Bernardina B, Villeneuve N, Nabbout R. SYNGAP1-DEE: A visual sensitive epilepsy. Clin Neurophysiol. 2021 Apr;132(4):841-850. doi: 10.1016/j.clinph.2021.01.014. Epub 2021 Feb 3. PMID: 33639450.


Objective: To further delineate the electroclinical features of individuals with SYNGAP1 pathogenic variants.

Methods: Participants with pathogenic SYNGAP1 variants and available video-electroencephalogram (EEG) recordings were recruited within five European epilepsy reference centers. We obtained molecular and clinical data, analyzed EEG recordings and archived video-EEGs of seizures and detailed characteristics of interictal and ictal EEG patterns for every patient.

Results: We recruited 15 previously unreported patients and analyzed 72 EEGs. Two distinct EEG patterns emerged, both triggered by eye closure. Pattern 1 (14/15 individuals) consisted of rhythmic posterior/diffuse delta waves appearing with eye-closure and persisting until eye opening (strongly suggestive of fixation-off sensitivity). Pattern 2 (9/15 individuals) consisted of diffuse polyspike-and-wave discharges triggered by eye closure (eye-closure sensitivity). Both patterns presented in 8/15. Including archived video-EEG clips of seizures from 9/15 patients, we analyzed 254 seizures. Of 224 seizures experienced while awake, 161 (72%) occurred at or following eye closure. In 119/161, pattern 1 preceded an atypical absence, myoclonic seizure or myoclonic absence; in 42/161, pattern 2 was associated with eyelid myoclonia, absences and myoclonic or atonic seizures.

Conclusions: Fixation-off and eye closure were the main triggers for seizures in this SYNGAP1 cohort.

Significance: Combining these clinical and electroencephalographic features could help guide genetic diagnosis.

Nagele EP, Gutierrez CA, Achieng E, Hopp JL. Fixation-off sensitivity in focal epilepsy due to posterior quadrantic dysplasia. Neurology. 2020 Sep 29;95(13):597-598. doi: 10.1212/WNL.0000000000010621. Epub 2020 Aug 11. PMID: 32788240.

Lee S, Oh DA, Bae EK. Fixation-off sensitivity in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. Seizure. 2019 Jan;64:6-7. doi: 10.1016/j.seizure.2018.11.010. Epub 2018 Nov 22. PMID: 30500480.


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