Search. Reactivity is a relatively good prognostic sign. Fisch B, Klass D. The diagnostic specificity of triphasic waves. Thirty years after the initial presentation of symptoms, the patient was referred for the evaluation of an early onset dementia, progressive behavioural disturbances, tremors, and gait disturbances. Roberto KT, Espritu AI, Fernande MLL, Gutierrez JC. Neurology 42(12):22862290, PubMed Kaplan P. EEG in metabolic encephalopathy and coma. Hashimoto encephalopathy. Encephalopathy is associated with generalized slowing due to disruption of the normal thalamocortical circuits. Less frequently, triphasic waves appear as one wave immediately following another. In: Niedermeyer E, Lopes da Silva, editors. These contractions occur approximately 50-60 milliseconds after each flash, disappear after eye opening and use of paralyzers, are located mostly frontally, and have no . The exception to the slowing would be in cases of mild intoxication with a sedative-hypnotic, such as a barbiturate or benzodiazepine where an increased amount of beta activity is seen before any slowing is noted. Photomyoclonic responses are most common in subjects with early alcohol withdrawal and in anxious patients. Vote. A photomyoclonic response is considered to be a myogenic component of eye flutter, and not an epileptiform pattern. This artefact, the photomyoclonic reflex (PMR), wasstudied bycovering the eye containing the recording electrode andstimulating the . This activity reflects the ongoing cortical activity as it happens. Triphasic waves are suggestive, but not diagnostic, of a metabolic cause of an encephalopathy (17). It is considered to be a normal physiological response which can, however, expand under emotional circumstances or metabolic or toxic states. PMR. Certain patterns of light flashing bright lights at particular frequencies synchronize cells within the visual cortex. The etiology is crucial in determining the prognosis. Some subjects contract the frontalis and orbicularis muscles. The severity of the slowing correlates with the degree of impairment of attention. More recently, research findings suggest a cortical origin of the photomyogenic reaction, which, however, remains to be elucidated [911]. In general, it does not help to reveal the etiology of the encephalopathy. Sporis D, Habek M, Mubrin Z, Poljakovic Z, Hajnsek S, Bence-Zigman Z. Psychosis and EEG abnormalities as manifestations of Hashimoto encephalopathy. Brain 122(Pt 3):461472, Garbutt, Harris CM (2000) Abnormal vertical optokinetic nystagmus in infants and children. Cold Spring Harbor Symposia on Quantitative Biology 1936;4:285-91. de la Paz D, Brenner RP. Moreover, the reticular reflex myoclonus is a response typically induced by touch, noise, tendon reflex, or muscle stretch. Brain 2010;133:3043-57. Activation methods typically used like photic stimulation and hyperventilation can rarely precipitate generalized tonic-clonic seizures (photic stimulation 0.04%, hyperventilation 0.03%) (66; 31). ), Frontal intermittent rhythmic delta activity (EEG). About 80% to 90% will have some sort of abnormal EEG, the most common abnormal pattern is generalized or background slowing (41). The site is secure. The inborn seizure response of Papio papio to intermittent light stimulation has been reviewed as a model of human epilepsy. Atonic temporary loss of muscle tone and consciousness, causing the patient to fall. Hypoxic (anoxic)-ischemic injury. Data suggest that there is substantial disagreement as to the EEG appearance of triphasic waves (20). In deep coma, the triphasic waves disappear and are replaced by diffuse delta slowing. J Clin Neurophysiol 2004;21:307-18. Our patient did not have seizures, making the clinical state of our patient more consistent with a progressive myoclonic ataxia. In children older than 8 years of age and in adults, there should be a posterior dominant rhythm (alpha rhythm) of at least 8.5 Hz. DOI: 10.1016/0013-4694(67)90104-6 Corpus ID: 4552937; Photomyoclonic response of epileptic and non-epileptic subjects during wakefulness, sleep and arousal. Foley JM, Watson CW, Adams RD. 2002 Dec;19(6):488-503. doi: 10.1097/00004691-200212000-00002. However, EMG activity bursts in our patient were of a long duration of 150200ms. Photomyoclonic, Photoconvulsive, Asymmetric, and Focal Responses. Google Scholar, Kanouchi T, Yokota T, Kamata T, Ishii K, Senda M (1997) Central pathway of photic reflex myoclonus. He increasingly presented action tremors, gait disturbances, falls, myoclonic jerks in the limbs and the body, and an increased startle response. Spontaneous changes in the EEG background and EEG reactivity are lost in deep coma. Even the worst patterns such as burst suppression or an isoelectric EEG can be associated with a good prognosis if due to a reversible cause, such as general anesthesia. Search over 14 million words and phrases in more than 490 language pairs. Epilepsy 2015;56(11):1845-54. A thorough analysis of the EEG morphology of the myclonic responses and the clinical manifestations showed evidence of two separate entitles of seizures namely: visually evoked pattern-myoclonic responses (PTMR) and visually evoked photomyoclonic responses (PMR). When discussing some of the EEG terms, I will also include the description in terms of how it would look like in the EEG terminology, when applicable. Lancet 1970;1:650-2. van der Zande JJ, Gouw AA, van Steenoven I, et al. Hypothyroidism. The alpha rhythm, or alpha, is attenuated in amplitude and frequency and often completely ablated by eye opening. 1.1. A broad set of conditions may present with an exaggerated startle reflex in clinics. Hypocalcemia produces progressive slowing of the EEG and at very low levels may produce generalized bursts of spike activity (43). Until puberty a normal intelligence and psychomotor development were reported. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. Epilepsy Behavior 2021;115:107682. CNS infections. These would be described as bilateral periodic discharges (BIPDs) using the critical care terminology. It is usually anteriorly predominant but can spread to more posterior regions if other muscles are involved in the eye contractions. Brain MRI studies showed diffuse cerebral atrophy, most severely of the frontal and temporal lobes. View Test Prep - Final Exam study guide EEG.docx from NDT A110 at Orange Coast College. Encephalopathy refers to global cerebral dysfunction, which manifests itself as slowing of activity in the cortex. Neurology 2020;95(6):e662-70. The electrographic and clinical features have been described and useful methodology has been outlined. Hypoxic (anoxic)-ischemic injury manifests across a spectrum from mild slowing to an isoelectric EEG, depending on the severity of the brain injury. All rights reserved. American Electroencephalographic Society. Periodic electroencephalogram complexes in a patient with variant Creutzfeld-Jakob disease. Patients also display extremely enlarged cortical components of somatosensory-evoked potentials and an enhanced C-reflex. Careers. Periodic lateralized epileptiform discharges (PLEDs). Vascular dementia. Periodic lateralized epileptiform discharges (PLEDs) are semi-rhythmic epileptiform (spikes or sharp waves or complexes) that usually occur at a frequency between 1 and 3 Hz. When the triphasic waves are separated by relative or diffuse attenuation, as they most commonly occur, it would be described as generalized periodic discharges (GPDs) with triphasic morphology. Triphasic waves and periodic complexes have been reported. . We report the case of 62-year-old woman referred to our department because of a clinical suspicion of tonic-clonic seizures. Thirtyyears after the initial presentation of symptoms, the patient was referred for the evaluation of an early onset dementia, progressive behavioural disturbances, tremors, and gait disturbances. Arch Neuro Psychiatr 1935;34:1133-48. Binelli S, Agazzi P, Giaccone G, et al. Most importantly, EEG can differentiate between a true acute encephalopathy and epileptic states or psychiatric conditions. Eriksson B, Wictor L. EEG with triphasic waves in Borrelia Burgdorferi meningoencephalitis. Lennox-Gastaut syndrome (LGS) is a type of epilepsy. VELMURUGENDRAN, v.UDAYAKUMAR SUMMARY Reflex epilepsy induced by sensory stimuli occured in 133 cases constituting 1.5% of all cases of epilepsies seen at Government Stanley Hospital and Medical College, Madras. Pancreatitis can also cause EEG changes, such as bilateral theta activity and intermittent delta activity (06). This site needs JavaScript to work properly. Liver enzymes, ammonia, sodium, calcium, and magnesium were normal. Baltimore: Williams & Wilkins, 1999:352. official website and that any information you provide is encrypted No follow-up EEG was performed. The normal reaction(response) consists in a diffuse deceleration of the basic /baseline rhythmicity of the EEG: the revealed slow- wave activity (capable of inducing EEG synchronization) is referred to as hyperventilation synchronization which is considered as a norm in all age groups [20] It should be noted that a . Theta, unreactive alpha, or spindle comas are, likewise, typically indicators of a poor prognosis for recovery of meaningful consciousness. Clinical and imaging correlates of EEG patterns in hopistalized patients with encephalopathy. American Journal of EEG Technology: Vol. https://doi.org/10.1007/s00415-010-5781-3, DOI: https://doi.org/10.1007/s00415-010-5781-3. The patient recovered. Hyperglycemia. Hypercalcemia. Hypocalcemia produces progressive slowing of the EEG and at very low levels may produce generalized bursts of spike activity (43). There were 3 metaanalyses of EEG abnormalities of generalized patients with COVID-19 infection (03; 50; 35). The EEG hallmark of acute encephalopathy is slowing of the background frequencies. A person loses consciousness, muscles stiffen, and jerking movements are seen. Hyperthyroidism produces an increase of the frequency of the posterior dominant rhythm, but thyroid storm may cause diffuse slowing, which has been rarely reported to be bitemporal (56). The first reference to the diffuse slowing seen in encephalopathic states appears to have been in a paper by Gibbs and colleagues published in 1935 (24). Motor exam showed a severe photomyogenic (photomyoclonic) response at photic ash ataxia of the extremities and muscle tendon reexes were stimulation during EEG recordings. MeSH terms Adolescent . The patient was a 64-year-old man who had undergone chemotherapy with melphalan and then total-body radiation prior to autologous stem cell transfusion for multiple myeloma. Naquet R, Menini C, Riche D, Silva-Barrat C, Valin A. Ital J Neurol Sci. At the age of 53 he succumbed from an aspiration pneumonia. Detection of hypoglycemia associated EEG changes during sleep in type I diabetes. This response consists of rhythmic activity that is time-locked to the stimulus and has a frequency identical or harmonically related to that of the flickering light. Murray K, Amin U, Stephanie Maciver, Benbadis SR. EEG findings in posterior reversible encephalopathy syndrome. Federal government websites often end in .gov or .mil. Immediate cessation of the response at the end of stimulation and prominent . Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips, Not logged in When Sleep Issues Prevent You from Achieving Greatness, Taking Tests in a Heat Wave is Not So Hot. Neurocrit Care 2016;24(2):233-9. Creutzfeldt-Jakob disease. The EEG hallmark of acute encephalopathy is slowing of the background frequencies. Endisch C, Westhall E, Kenda M, et al. Clin EEG Neurosci 2016;47(1):61-8. Of these nine, seven had multifocal discharges corresponding with contralateral jerky movement and photosensitivity (photoparoxysmal response, photomyoclonic response). "Ictal" lateralized periodic discharges. A seizure that lasts longer than 5 minutes, or having more than 1 seizure within a 5 minutes period, without returning to a normal level of consciousness between episodes is called status epilepticus. Binswanger-type dementia is characterized by diffuse slowing. Encephalopathy: slowing of background frequencies on EEG (1). Baltimore: Williams & Wilkins, 1999:420-22. In 1936, an article by Davis was published and included mention of this issue (13). Photomyoclonic response: Forehead and muscle twitching in response to light flash, disappearing with eye opening. Photomyoclonic seizures in the baboon, Papio papio. Arch Neurol 1980;8:341. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Unfortunately, EEG patterns rarely are truly pathognomonic for any specific cause of encephalopathy, but some may be suggestive of an etiology. HHS Vulnerability Disclosure, Help Frontal intermittent rhythmic delta activity (FIRDA) is shown as high amplitude, intermittent, 2 to 3 Hz semirhythmic activity that has anterior prominence. Cassani R. Estarellas M, San-Martin R, Fraga FJ, Falk TH. One exception is the chronic encephalopathy of subacute sclerosing panencephalitis (see below). Most waves of 8 Hz and higher frequencies are normal findings in the EEG of an awake adult. Clin Neurophysiol 2013;124(1):44-51. Acute encephalopathies range from delirium to coma. In: Niedermeyer E, Lopes da Silva, editors. Breathing problems or stopping breathing. The abnormalities may consist of diffuse or focal slowing, or focal or generalized epileptiform discharges, or both. Falling suddenly for no apparent reason, especially when associated with loss of consciousness. Hypocalcemia. Photosensitive seizures are triggered by flashing or flickering lights. The recognition of vertical gaze palsy by electro-oculography has been described [14]. Song TJ, Kim, SJ, Kim GS, Choi YC, Kim WJ. The evaluation of altered mental status and of seizures is the main indication for an EEG. J Clin Neurophysiol 1986;3:144-9. Listen to MedLink on the go with Audio versions of each article. Electrocerebral inactivity (silence) is defined as the lack of any cerebral electrical potentials that are greater than 2 mcV in amplitude. Hoagland published another article on this topic in 1937 (27). The posterior regions showed a normal photic driving response. Thats what happens in the brain during a seizure. If asymmetric between the 2 hemispheres, this would be . PMID: 5389063 No abstract available. only duringthe first 55 to 60msofthe response. The EEG records the electrical potential differences between different sites on the scalp, not the absolute voltage. Consecutive EEG recordings showed a background pattern of 89Hz which slowed towards 78Hz. 49-66. Hypercalcemia also causes slowing and can cause spikes as well as triphasic waves (32). Hepatic encephalopathy. forehead and muscle twitching in response to light flash, disappearing with eye opening, are most common in subjects with early alcohol withdrawal and in anxious patients . The severity of the slowing correlates with the degree of impairment of attention. Systematic review of EEG findings in 617 patients diagnosed with COVID-19. EEG in Pick disease may appear normal to visual inspection, but computerized analysis may show subtle slowing (07). Normal photic driving has long been known to be potentially reduced on the side of a lesion. Two cases of cortical myoclonus and one case on a progressive cortical action myoclonus on motor activity have been described [4, 5]. Dr. CAS Given the many conflicting papers and the moderately high risk of bias of the paper, this result should be considered as only a possible correlation until replication. MRI of the brain was also normal. The lack of reactivity, conversely, is a poor prognostic sign with a relative risk of 3.7 (95% confidence interval 2.0 to 6.9) of death for both nonhypoxic (59) and hypoxic patients. In our patient, EMG activity was mostly dominant in the posterior regions. The severity of the slowing correlates with the degree of impairment of attention (51). The electroretinogram is a mass electrical response of the retina to photic stimulation. Peak metabolic rate. Dictionary, Encyclopedia and Thesaurus - The Free Dictionary, the webmaster's page for free fun content, Photon Amplification By Stimulated Emission of Radiation :-), Photon Assisted Scanning Tunnel Microscopy, Photon Emission Scanning Tunnel Microscopy. Greater than anticipated amounts of theta or beta activity, or any delta activity (3 to 4 Hz), in a fully alert patient indicates an encephalopathy. Electroencephalogr Clin Neurophysiol. Electoencephalogr Clin Neurophysiol 1965;19:314-6. Open Button. The photomyoclonic response occurs because of muscle activity from brief contractions of the eyes in response to the light flicker. [Published with video sequences] Key words: startle, photomyoclonic response, hypocalcemia, serum electrolyte 84 8600 Rockville Pike NP-C was diagnosed when the accumulation of unesterified cholesterol by positive fibroblast Filipin staining and reduced LDL cholesterol esterification in fibroblasts was demonstrated. Chronic encephalopathies, such as dementias, often are associated with normal EEGs until relatively late in the course of the disease. These seizures can also be triggered by certain patterns such as stripes. Electroencephalogr Clin Neurophysiol 1986;1986:540-6. J Neurol 258, 521523 (2011). American Clinical Neurophysiology Societys Standardized Critical Care EEG Terminology: 2012 version. Diabetes Res Clin Pract 2012;98(1):91-7. 2, pp. 1). In the literature the neurophysiological findings of NP-C are described in only a number of reports [2, 4, 5]. An article was published in 1937 that looked at encephalopathy caused by medication (23). He was noted to have an altered mental status about 2 weeks later. The electro-encephalogram in epilepsy and in conditions of impaired consciousness. Clinical utility of EEG in diagnosing and monitoring epilepsy in adults. Abstract. Frontal intermittent rhythmic delta activity (FIRDA). J Clin Neurophysiol 2013;30(1):1-27. Motor exam showed a severe ataxia of the extremities and muscle tendon reflexes were increased, but not pathologic. ACR appropriatenesscriteria: headache in children, Guidelines: Prediction of outcome in comatose survivors after cardiopulmonary resuscitation. Dis Markers 2018;2018:5174815. Romano J, Engel G. Delirium: electroencephalographic data. Gibbs FA. The EEG hallmark of acute encephalopathy is slowing of the background frequencies. This can be accomplished by using alerting stimuli such as asking the patient to count or, if necessary, using noxious stimuli. Seizure 2020;81:198-200. Alpha coma and spindle coma. The EEG hallmark of acute encephalopathy is slowing of the background frequencies. The present report discusses the difficulties in distinguishing between epileptic and non-epileptic . No specific EEG finding is sufficient to independently determine the prognosis. 1967 Aug;23(2):142-51. The purpose of this study was to determine the clinical correlates of the photomyoclonic response to intermittent light stimulation alone in psychiatric patients. Trans Am Neurol Assoc 1950;75:161-4. EquipmentA) A min. EEG in Parkinson disease is normal in 48% to 64% of the patients (16; 68). PDF; Imprimer; Ajouter mes favoris; Citer cet article; Envoyer un lien vers article; Partager sur Facebook . Electroencephalogr Clin Neurophysiol 1988;70:1-8. Alpha coma and spindle coma are characterized by nonreactive diffuse alpha or sleep spindle-like (approximately 14 Hz) activity. In response to photic stimulation (p. 40), it is usual to observe the so-called driving response over the posterior regions of the head. This so-called "photomyoclonic response" occurs in 0.1% of normal population and 1% of patients with epilepsy. The most common cause is stroke, which in one series occurred in 53% of patients with PLEDs (46). However, the sodium concentration does not cause slowing as much as the rate of its decrease. The .gov means its official. Subacute sclerosing panencephalitis is classically associated with periodic complexes that are very stereotyped and occur once every 5 to 7 seconds. The most typical physiological response is a symmetric driving response, in which an occipital rhythm is seen that matches the frequency of the photic stimulation (for example, a 10 Hz flash frequency of photic stimulation elicits a driving response of 10 Hz in the occipital head regions). DOI: 10.1080/00029238.1969.11080737; Myoclonic responses generated by the reticular formation typically induce a motor reflex of the orbucularis oculi muscle 40ms after the stimulus. SHAGASS C. Electroencephalography and Clinical Neurophysiology, 01 Aug 1954, 6(3): 445-453 DOI: 10.1016/0013-4694(54)90059- PMID: 13200416 . This EEG from an unresponsive (comatose) patient shows predomina Encephalopathy: slowing of background frequencies on EEG (2). OIRDA is most frequently seen in children with absence epilepsy. All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. EEG findings of encephalopathies are typically of nonspecific etiology. When diagnosing brain death, the EEG needs to be recorded according to specific guidelines (02) The ACNS criteria include double-distance electrode placement, checking each electrode during the recording, sensitivity set to 2mcV, and at least 30 minutes recording duration. Hypothyroidism is associated with progressive slowing of the background and a low-amplitude record. Semantic Scholar's Logo. Photic driving. Seizure 2020;83:234-41. Photoconvulsive Response and Disposition Photoconvulsive Response and Disposition Takahashi, Takeo 1976-09-01 00:00:00 Department of Neuropsychiatry, Tohoku University School of Medicine, Sendai INTRODUCTION The photoconvulsive response (PCR) is a paroxysmal discharge provoked by intermittent photic stimulation (IPS)of stroboscopic light, and the PCR is most highly seen in . photomyogenic (photomyoclonic) response at photic ash stimulation during EEG recordings. 85% of reflex seizures are generalized tonic-clonic seizures. ACNS guidelines for minimal requirements for a routine EEG 1. These types of seizures usually last 1 to 3 minutes and take longer for a person to recover. Rzenicka-Glinka, Z., 1965: Studies of electroencephalographic arousal in the first stage of sleep induced by fenactyl in healthy and epileptic persons It can also assess changes in brain function over time and in response to stimuli. activity are seen more anteriorly. Foreman B, Mahalikar A, Tadi P, et al. The series of 11 cases from Peru had 7 patients with the 1 to 2 Hz periodic complexes (62), suggesting possibly that not all patients with Creutzfeldt-Jakob disease have periodic complexes. This pattern can sometimes be confusing, because it can respond to benzodiazepines or antiepileptic drugs in about one third of cases (45). Myoclonus can have a cortical origin or it can be generated by the brain stem showing mechanisms similar to the blink reflex or in the reticular formation. Hypernatremia is associated with generalized high voltage slow activity (22). Electroencephalographic sleep elements and outcome in acute encephalopathy patients: a 4-year- cohort study. Luecking C. Sleep-like patterns and abnormal arousal reactions in brain stem lesions. This pattern was once felt to be diagnostic of mid-line cerebral patholog Occiptial intermittent rhythmic delta activity (EEG), Occiptial intermittent rhythmic delta activity (OIDRA) is most frequently seen in children with absence epilepsy. A photomyoclonic response is considered to be a myogenic component of eye flutter and not an epileptiform pattern. and transmitted securely. The complexes contain stereotyped sharp and slow waves. Renal encephalopathy. BiPLEDs are simply PLEDs that occur independently in each cerebral hemisphere. Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. Herein, we report a case of a Triphasic waves were first described in 1950 as blunted spike and wave (19). Triphasic waves. Our J Neurol 2014;21(10):1268-75. GRDA is not allowed to include a triphasic morphology as a descriptor, so would include anterior-posterior lag descriptor (if it were present). Sutter R, Barnes B, Leyva A, Kaplan PW, Geocadin RG. try to eliminate by reducing cause of sweating (example: cool head, wipe area with alcohol, air conditioning) monitor by placing two leads on the hand; one on the palm and one on the dorsum. Clin EEG Neurosci 2019;50(5):366-9. Correspondence to [A contribution to the study of the photomyoclonic response] [A contribution to the study of the photomyoclonic response] Seishin Shinkeigaku Zasshi. Current Practice of Clinical Electroencephalography. The frequencies continue to slow as the coma deepens. The most common form of reflex epilepsy is photosensitive epilepsy, in which flashing lights trigger seizures. In one series, lack of reactivity yields 98% positive predictive value of unfavorable outcome in hypoxic encephalopathy. Photomyoclonic, Photoconvulsive, Asymmetric, and Focal Responses. Ann Neurol 2006;59(2):423-7. @article{MeierEwert1967PhotomyoclonicRO, title={Photomyoclonic response of epileptic and non-epileptic subjects during wakefulness, sleep and arousal. Yeager C, Alberts W, Delattre L. Effect of stereotaxic surgery upon the electroencephalographic status of parkinsonian patients. This artefact, the photomyoclonic reflex (PMR), was . Britt C. Nontraumatic spindle coma: clinical, EEG, and prognostic features. Full spectrum of neurology in 1,200 comprehensive articles. Thirty years after the initial presentation of symptoms, the patient was referred for the evaluation of an . Can diffusion-weighted imaging be used as a tool to predict seizures in patients with PLEDS? However, in our patient, evoked potential studies were not performed. In: Daly D, Pedley T, editors. Electroencephalographic findings in COVID-19 patients: a systemic review. Acta Neurol Scand 2007;116(2):133-6. There are only rare adverse effects, although the adhesive used for longer-term recordings is a frequent cause of hair loss. These would be described as generalized periodic discharges (GPDs) using the critical care terminology. Is it healthier to drink herbal tea hot or cold? J Clin Neurophysiol 2011;28:233-51. The photomyoclonic response (PMR) consists of bilateral muscle con- tractions that are synchronous with the flash rate. [Creutzfeldt-Jakob disease in Peru: report of eleven cases]. Epilepsy Behav 2014;36:165-70. EEG features reported consist of unspecific diffuse slowing of background activity. Here are some of the seizure triggers that have been reported by people with epilepsy: Too much texting and exposure to computer screens electronic stress can set off an epileptic attack. J Neurol Neurosurg Psychiatry 62(4):414417, Shibasaki H (2006) Neurophysiological classification of myoclonus. Factors like emotional stress, skipping meals, sleep deprivation, fatigue, smoking, alcohol consumption, etc. As the electrical potentials change over time, the EEG records these changes as waves. Hyperthyroidism. The frequencies continue to slow as the coma de Encephalopathy: slowing of background frequencies on EEG (3). As the disease progresses, more and more diffuse theta and then delta slowing is seen (12). Google Scholar, Floyd AG, Yu QP, Piboolnurak P, Wraith E, Patterson MC, Pullman SL (2007) Kinematic analysis of motor dysfunction in NiemannPick type C. Clin Neurophysiol 118(5):10101018, Canafoglia L, Bugiani M, Dalla Bernardina B et al (2006) Rhythmic cortical myoclonus in NiemannPick disease type C. Mov Disord 21(9):14531456, Article A control group of 30 non-patient subjects was . photomyoclonic; denoting an electroencephalographic response to photic stimulation (brief flashes of light) marked by myoclonus of the facial muscles. The patient was febrile, but no source of infection was found despite pan-culturing that included cerebrospinal fluid. Bilateral PLEDs (BiPLED). The purpose of obtaining an EEG is to assess cerebral function. Torres-Ramirez L, Ramirez-Quinones J, Cosentino-Esquerre C, et al.