Electromagnetic Hypersensitivity Evidence For A Novel Neurological Syndrome McCarty Marino July 2011
Electromagnetic Hypersensitivity Evidence For A Novel Neurological Syndrome McCarty Marino July 2011
Electromagnetic Hypersensitivity Evidence For A Novel Neurological Syndrome McCarty Marino July 2011
Objective: We sought direct evidence that acute exposure to environmental-strength electromagnetic elds could induce somatic reactions (EMF hypersensitivity). Methods: The subject, a female physician self-diagnosed with EMF hypersensitivity, was exposed to an average (over the head) 60-Hz electric eld of 300 V/m (comparable to typical environmental-strength EMFs) during controlled provocation and behavioral studies. Results: In a double-blinded EMF provocation procedure specically designed to minimize unintentional sensory cues, the subject developed temporal pain, headache, muscle-twitching, and skipped heartbeats within 100 s after initiation of EMF exposure (P < 0.05). The symptoms were caused primarily by eld transitions (off-on, on-off) rather than the presence of the eld, as assessed by comparing the frequency and severity of the effects of pulsed and continuous elds in relation to sham exposure. The subject had no conscious perception of the eld as judged by her inability to report its presence more often than in the sham control. Discussion: The subject demonstrated statistically reliable somatic reactions in response to exposure to subliminal EMFs under conditions that reasonably excluded a causative role for psychological processes. Conclusion: EMF hypersensitivity can occur as a bona de environmentally-inducible neurological syndrome.
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Clifton Frilot II, Ph.D.b, Eduardo Gonzalez-Toledo, M.D.c, Andrew A. Marino, Ph.D.a,*
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Center, P.O. Box 33932, Shreveport, LA 71130-3932, USA. Tel.: 1-318-675-6177. E-mail address: amarino@lsuhsc.edu
Running head: Electromagnetic Sensitivity Keywords: Electromagnetic fields, Evoked potentials, Hypersensitivity, Provocation
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School of Allied Health Sciences, LSU Health Sciences Center, Shreveport, LA, USA
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David E. McCarty, M.D.a, Simona Carrubba, Ph.D.a, Andrew L. Chesson, Jr., M.D.a,
ABSTRACT Objective: We sought direct evidence that acute exposure to environmental-strength electromagnetic fields could induce somatic reactions (EMF hypersensitivity).
was exposed to an average (over the head) 60-Hz electric field of 300 V/m (comparable to typical environmental-strength EMFs) during controlled provocation and behavioral
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studies.
minimize unintentional sensory cues, the subject developed temporal pain, headache, muscle-twitching, and skipped heartbeats within 100 s after initiation of EMF exposure
rather than the presence of the field, as assessed by comparing the frequency and severity of the effects of pulsed and continuous fields in relation to sham exposure. The subject had no conscious perception of the field as judged by her inability to report its presence more often than in the sham control. Discussion: The subject demonstrated statistically reliable somatic reactions in response to exposure to subliminal EMFs under conditions that reasonably excluded a causative role for psychological processes.
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Conclusion: EMF hypersensitivity can occur as a bona fide environmentally-inducible neurological syndrome.
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(P < 0.05). The symptoms were caused primarily by field transitions (off-on, on-off)
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INTRODUCTION Man-made electromagnetic fields (EMFs) such as those produced by cell phones, powerlines, or computers are ubiquitous in the general and workplace
hypersensitivity) [1, 2]. The prevalence of self-reported EMF hypersensitivity has usually
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discovery of the ability of human beings to detect weak EMFs, as evidenced by the occurrence of field-onset and field-offset brain potentials [5], and the induction of
field [6]. The underlying mechanism of field sensory transduction appears to be an electric-force-sensitive ion channel [7]. Animal studies suggest that the electroreceptor cells and/or afferent processing cells are located in the brain stem [8, 9]. Despite the physiological and biophysical evidence that could explain at least some cases of human somatic responses to EMFs without invoking psychological processes [5-9], direct evidence of nonpsychological EMF hypersensitivity is lacking. Our purpose was to determine whether EMFs could produce symptomatic responses in
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a putatively hypersensitive subject, while appropriately controlling for chance, confounders, and somatization.
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steady-state changes in brain electrical activity that persisted during the presence of the
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METHODS Subject In the context of ongoing human, animal, and biophysical studies involving EMF
physician with multiple neurologic and somatic symptoms including headaches, hearing and visual disturbances, subjective sleep disturbances and nonrestorative sleep, and
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environmental triggering sources she identified were cell phones, computers, powerlines, and various common electrical devices. During extensive interviews she
After she agreed to medical tests appropriate for evaluating her medical condition, she was admitted as a patient on the neurology service and underwent a physical exam including a comprehensive neurologic exam, a clinical electroencephalogram (EEG) exam, a noncontrast magnetic-resonance (MR) imaging of the brain, an overnight sleep study (with video and expanded EEG montage) in which the resulting polysomnogram was scored in accordance with standardized rules [10], a
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standard laboratory evaluation of serum electrolytes and blood chemistries, liver function tests, serum fasting cortisol, and complete blood count, and direct evaluations of her EMF sensitivity in a series of EMF provocation and behavioral studies (see below). The institutional review board at the LSU Health Sciences Center approved all experimental procedures, and the subject gave her written informed consent.
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credibly explained the reasons for her belief that EMFs from common environmental
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to environmental EMFs and abated by withdrawal from the fields. Among the
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EMF Exposure The subject sat in a comfortable wooden chair with her eyes closed, and uniaxial
voltage to parallel 49-cm square metal plates spaced 36 cm apart (Figure 1). The
equipment that controlled the field was located outside the subjects view and emitted
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no visual or auditory stimuli. The background electric field (the field present irrespective
throughout the region occupied by the subject (HI-3603, Holaday, Eden Prairie, MN, USA). The plate arrangement did not produce magnetic fields. The continuously-present
599.8 mG, 68.4 below the horizontal component (component along the direction of the applied field, 360.5 mG) (MAG-03, Bartington, GMW, Redwood City, CA, USA). Highfrequency signals from cell-phone towers and other distant antennae (110 GHz) were less than 0.1 W/cm2 (the background fields in the sleep-study room were similar) (Spectran, Aaronia, Euscheid, Germany). In the provocation studies the electric field was applied for 100-s intervals with a duty cycle of 50% and a repetition rate of 10 Hz, which resulted in alternating field-on
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and field-off pulses of 100 ms (pulsed field); a continuous field (100% duty cycle) was used in one of the provocation studies. Duty cycle, pulse structure, and interval length were regulated by a microcontroller programmed to produce the desired signals. When the duty cycle was 50% the actual EMF stimuli consisted of: 1) 10 onset stimuli per second x 100 s = 1000 field-onset stimuli per interval; 2) an equal number of field-offset
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background 60-Hz magnetic field was 0.1 mG, and the geomagnetic field was
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of whether or not a voltage was applied to the parallel plates) was about 1 V/m
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60-Hz (unless noted otherwise) sinusoidal electric fields were generated by applying a
stimuli; 3) the presence of the EMF for a total of 50 s. When the duty cycle was 100% there was only 1 field-onset stimulus and 1 field-offset stimulus, and the EMF was present for 100 s. In the behavioral studies the electric field was applied in trials
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Field Strength
resulting in strong inhomogeneities in the field surrounding the subject. To overcome the problem of measuring the external field, we used Maxwells laws to calculate it at
composite of rectangular solids representing the trunk and lower extremities, and an ellipsoid representing the head. The assumed conductivity was 1 S/m. The total electric field at every point was determined for VAC = 100 V using finite-element analysis consisting of approximately 106 elements; a more detailed mesh was automatically generated in the head region (Multiphysics, Comsol, Los Angeles, CA, USA). The peak external electric field was about 1000 V/m (Figure 1); the average field was about 300 V/m around the head, and less than 50 V/m around the body. The peak and average
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field strength and duration of exposure were far below the levels generally recognized as capable of producing physiological effects in human subjects [11]. The external electric field resulted in an induced internal electric field in the brain in accordance with physical law. The strength of the induced brain electric field was comparable to that induced by environmental-strength power-frequency electric and
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every point in the subjects vicinity. The subject was modeled as an electrically isolated
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The applied electric field was significantly distorted by the subjects body,
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consisting of a 2-s epoch when a pulsed field was applied (50% duty cycle, 10-Hz
Somatic Responses
exposure intervals. The controls were ten 100-s sham-exposure intervals during which a field was not applied. The order of the field and sham intervals was determined
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disconnected during the sham-exposure intervals. At the end of each interval the subject was questioned by an interviewer blinded to whether or not the field had been
whether or not the symptoms had persisted into the interview period. She was queried using descriptive terms she had employed. Whenever she reported symptoms, commencement of the next interval was delayed until she reported that they had abated.
We used a pulsed field because we expected it would result in a stronger symptomatic response compared with a continuous field [9, 14]. To test this reasoning we performed a second study to assess whether the subject developed a differential
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symptomatic response to the pulsed and continuous fields. The subject was exposed or sham exposed for 100-s intervals, and immediately after each interval was interviewed as described above. A sham field (S), continuous field (C) (100% duty cycle), and pulsed field (P) (50% duty cycle, 10 Hz) were applied, and the SCP pattern was repeated five times. The subject was blinded regarding the use of different EMFs; from
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applied and asked to describe any symptoms she developed during the interval,
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intervals were identical except that the wires carrying the plate voltage were
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A pulsed field (50% duty cycle) was applied for 100 s in ten independent field-
her perspective the laboratory procedures were identical to those followed in the first study. The interviewer was aware that the effects of C and P fields were being compared, but was blinded regarding the actual sequence of the fields.
Behavioral Responses
determining whether the subject could consciously perceive a field when it was presented in multiple independent trials. A field having the same strength and spatial
consisted of a 2-s epoch during which a pulsed field (50% duty cycle, 10-Hz repetition rate) was applied and a 10-s field-free control epoch. Eight independent sequences were employed, each with 3050 trials. In three sequences the frequency was 60 Hz, in two it was 1 kHz, and in three others the respective frequencies were 10 kHz, 100 kHz, and 500 kHz.
The subject held a small plastic box that housed a buzzer, a button labeled YES and another button labeled NO. In the middle of each on and off epoch the buzzer
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emitted a 4-kHz tone at 60 dB which lasted 100 ms, and she was instructed to press the YES or NO button whenever she heard the tone, depending on whether or not she had any conscious sensation of a field at that moment. Employing a custom-designed virtual instrument (LabView, National Instruments, Austin, TX, USA), we determined the number of YES and NO responses in the presence and absence of the field in each
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reaction based on a fear that EMFs were harmful. We approached the issue by
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sequence. In addition, 4 sham sequences (minimum of 30 trials in each) were conducted in which a field was not applied. The subject had no knowledge that an off-on pattern was being used in the field sequences or that some sequences consisted of
Statistics
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The frequencies of the somatic and behavioral responses in the presence and
Clinical Studies
The patients physical examination was unremarkable. The presence of frequent subjective awakenings from sleep, sometimes with unintended gross motor activity such as muscle twitching and leg jerking, prompted clinical concern for a sleep-related movement disorder, parasomnia, or nocturnal epilepsy. The polysomnogram revealed significant sleep fragmentation and discontinuity (Table 1), but no evidence of significant sleep-disordered breathing, nocturnal epilepsy, or abnormal REM-related atonia.
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Periodic limb movements were noted, but did not appear to be a major sleep-disrupting
force.
Standard and 24-hour video-accompanied EEG recordings revealed normalappearing background rhythms and no epileptiform activity. EEG performed in the presence of active cellular telephone use provoked a right-sided headache, but
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RESULTS
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absence of the field were evaluated using the chi-square test (2 x 2 tables) or the
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sham exposure.
produced no unusual EEG waveforms. The MR image revealed evidence of cortical dysplasia in the right temporal lobe, and right parietal polygyria, both without interval change when compared with a study performed 19 months earlier. Laboratory
was unremarkable.
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Somatic Responses
The question of a relation between the presence of the field and the occurrence
100-s field-exposure or sham-exposure intervals; both the interviewer and the subject were blinded regarding the exposure condition. During the interviews the subject reported a range of symptoms including localized pain in her jaw, ear, or the side of her head, a more diffuse head pain, and muscle pain or twitching in the hip, neck, and back. Sometimes she qualified the symptom as strong or mild, and sometimes she denied all symptoms. We grouped the symptoms related to localized head pain as temporal pain, those related to diffuse head pain as headache, and those related to muscle
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effects as muscle pain/twitching. Symptoms reported more rarely were indicated explicitly (Table 3a). The subject consistently reported pronounced symptoms that occurred during the field intervals, particularly in intervals 7, 13, 14, 15, and 18. In the sham intervals she reported no symptoms in intervals 4, 6, 8, 16, 20, weak temporal
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pain in intervals 2, 3, 19, and a weak headache in intervals 10 and 12. The field and sham distributions of symptoms differed significantly (P < 0.05) (Table 3b). In a second study, the relative role of EMF changes (number of onsets and
the subject immediately following 100-s exposure intervals in which either a pulsed field or a continuous field was presented. She was queried regarding her symptoms as
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previously and reported symptoms in both field intervals (Table 4a). The symptoms
(P < 0.05) (Table 4b); the symptoms triggered by the continuous field did not differ from the sham control (P = 0.16). The subject reported no symptoms in 4 of 5 sham intervals
Behavioral Responses
The possible influence of conscious awareness of the EMF on the development of symptoms was investigated by assessing whether the subject could consciously perceive the field. A total of 300 independent trials involving carrier frequencies of 60 Hz to 500 kHz were used; the controls consisted of 150 sham trials. The results did not depend on the carrier frequency, and consequently the data was combined for analysis
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(Table 5).
The subject failed to respond to the tone 7 times while the field was on and 7
times while it was off, resulting in a total of 293 responses for each of the two conditions. There were no missed responses in the sham trials. The overall yes response rate in the field trials was (51/586) x 100 = 8.7%. The occurrence of a yes
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triggered by the pulsed field were more intense compared with the sham control
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offsets) and steady-state presence of the EMF was directly addressed by interviewing
response was significantly associated with the presence of the field (P < 0.05) (Table 5a), but the sensitivity of the yes responses was low ([32/(32 + 261)] x 100 = 11%). The yes response rate in the sham trials was slightly higher than that seen in the field trials
DISCUSSION
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psychological and nonpsychological processes in mediating any observed symptoms. A working laboratory definition of EMF hypersensitivity formulated in symptomological
occur. In previous provocation studies the assumption was made that true hypersensitive subjects would exhibit more or less the same symptoms in response to repeated provocations. The assumption led to experimental designs that involved averaging across exposed and control groups, which is an inherently insensitive statistical procedure for detecting real but variable responses [3, 4]. The assumption is particularly inapplicable to EMF hypersensitivity because intra- and inter-subject variability are its salient features [1, 2]. We defined EMF hypersensitivity as the
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occurrence of any medically recognized symptom in response to provocation using an environmentally relevant EMF; there was no requirement that the same symptom must
reoccur when the EMF provocation was repeated. This definition avoided the problem of masking real effects and more appropriately matched the laboratory procedure to the known characteristics of EMF hypersensitivity [1, 2]. We focused on a single self-
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reported subject and employed a procedure in which she served as her own control. While controlling for artifacts, chance, and somatization, the question whether she reliably exhibited any symptomatic responses to an EMF was addressed; the alternative
conditions were controlled in such a way that a putative role of psychological processes could reasonably be identified.
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the basis of chance (Table 3). Several considerations suggested that the statistical link was a true causal association with a subliminal EMF. First, the subjects environment
an acoustically quiet environment and the presence of uncontrolled environmental EMFs was nil. The environmental conditions during the field-exposure and shamexposure intervals were identical except that during the sham-exposure intervals, at a point far removed form the subjects field of view, the wires carrying the plate voltage were disconnected. A key aspect of our laboratory procedure was the elimination of sensory cues that could serve as conscious markers of the electric field leading to a somatization reaction. All appropriate precautions were taken to eliminate potential
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confounders. Second, the occurrence of symptoms was significantly associated with the type of EMF (Table 4). The symptomatic response was associated with the pulsed EMF, which maximized occurrence of the number of transient changes in the EMF (off-on and on-off), not with the presence of the field, as expected on the basis of prior animal studies where the issue of somatization was irrelevant [9]. Finally, in a behavioral study
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was carefully controlled to avoid putative confounding factors. The testing took place in
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electric field significantly (P < 0.05) more often than could reasonably be explained on
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hypothesis was that she did not exhibit EMF-triggered symptoms. The laboratory
specifically designed to assess awareness of the field, yes response rates were 8.7% and 9.9% in the field and sham conditions, respectively, which provided no evidence for a psychological role in the development of the subjects symptoms. We therefore
between the presence of the EMF and the subjects symptoms was mediated by a
subconscious neural process. Although chance was an unlikely explanation for the
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association, that possibility could not be excluded. The existence of the neurological
The mechanism for the subjects symptoms of headache, visual disturbances, and somatic musculoskeletal discomfort following exposure to EMFs is unknown. Based
a deeper epileptic focus with partial seizure activity may have escaped the detection of surface EEG electrodes. The abnormal findings in the subjects medical workup included the abnormal MR image (cortical dysplasia and polygyric changes) and extensive sleep discontinuity and fragmentation manifested in the overnight polysomnogram; the possible association of these findings with the subjects syndrome of EMF hypersensitivity is unknown. Our aim here was to concentrate on the previously unaddressed question
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whether acute exposure to weak EMF could produce real but not precisely predictable somatic effects mediated by nonpsychological processes. Within the limitations of the study we concluded that we demonstrated the neurological syndrome in the subject we studied. The question of whether EMF hypersensitivity is a significant public-health problem was not addressed here. The EMF we employed was equivalent in strength
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conclude with a reasonable level of certainty that the causal association we found
and pulse structure to EMFs pervasively present in the environment [1, 2], and our results were consistent with the possibility that environmental EMFs can directly trigger clinical symptoms. Nevertheless resolution of the public-health issue depends on a
to physiological process, and of the role of psychological factors and co-morbidities in the exposed population in exacerbating the processes resulting in disease.
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alone are responsible for the content and writing of the paper.
1.
electromagnetic field exposure: a cross-sectional representative survey in Switzerland. Soz Praventivmed. 2006;51:183-4. 3. Rubin GJ, Das Munshi J, Wessely S. Electromagnetic hypersensitivity: a
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systematic review of provocation studies. Psychosom Med. 2005;67:224-32. 4. Rubin J, Nieto-Hernandez R, Wessely S. Idiopathic environmental intolerance
attributed to electromagnetic fields. Bioelectromagnetics. 2010;31:1-11. 5. Carrubba S, Frilot C, Chesson Jr. AL, Marino AA. Evidence of a nonlinear human
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syndrome patients. Clin Neurophysiol. 1999;110:1168-74. 22. American Academy of Sleep Medicine. The International Classification of Sleep
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Freeman GH, Halton JH. Note on exact treatment of contingency, goodness of fit
Table 1 Polysomnography Results. Comparison with usual night, per patient: Same as usual. No epileptiform activity noted during arousals associated with unintended gross motor activity. Normal REM-related atonia. REM, rapid eye movement; WASO, wake
SUBJECT
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Sleep latency Stage N1 sleep Stage N2 sleep Stage N3 sleep Stage R sleep REM latency WASO index WASO total Total sleep time Sleep efficiency Arousal index PLM index AH index
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150.5 min 6/hr
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40.5 min
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4455% [17] 1015% [17] 2025% [17] 5766 min [18] 1.3 0.8 [16] 10.7 11 min [19] 340.0 70 [16] 86.4% 11.6 [16] 16.8 6.2 [20] < 5/hr [21] < 5/hr [22]
38% [17]
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Table 2 Sequence and characteristics of experiments. ELECTRIC FIELD CONDITION Pulsed Sham TRIAL DURATION (sec) 100 100
EXPERIMENT 1
NO. OF TRIALS 10 10
RESPONSE Symptoms
2
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5 5 5
Pulsed Sham
300 150
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1 1
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Symptoms Behavior
Table 3 Evaluation of the relation between presentation of a pulsed electric field and the development of symptoms. (a) Results from the individual 100-s exposure intervals. (b) Summary table.
(a)
INTERVAL NO. 1
CONDITION Pulsed Field Sham Sham Sham Pulsed Field Sham Pulsed Field Sham
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2 3 4 5 6 7 8 9 10 11 12
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13 14 15
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Pulsed Field Pulsed Field Sham Pulsed Field Pulsed Field Sham Sham
16 17 18 19 20
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No symptoms
Temporal pain Mild headache Muscle twitch; Feeling of unease Strong headache Strong headache No symptoms Stiff neck Muscle twitch; temporal pain Mild temporal pain No symptoms
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(b)
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Sham FIELD CONDITION
*Pulsed Field
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NONE 0 5
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*P < 0.05
0
21
SYMPTOMS MILD 0
10
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> MILD
Table 4 Evaluation of the comparative effect of continuous and pulsed fields relative to a sham field on the development of symptoms. (a) Results from individual 100-s exposure intervals. (b) Summary table.
(a)
RESULT
No symptoms
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2 3 4 5 6 7 8 9 10 11 12
Continuous Field Pulsed Field Sham Continuous Field Pulsed Field Sham
No symptoms
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13 14 15
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Continuous Field
Pulsed Field
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No symptoms No symptoms Mild headache Mild headache Muscle twitch Severe pain No symptoms Temporal pain Headache; Muscle twitch No symptoms Mild temporal pain Mild temporal pain
Temporal pain
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(b)
Sham
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CONDITION
*Pulsed field
Continuous Field
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NONE 0 2 4 2 0 1 MILD
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*P <0.05
3
SYMPTOMS
23
0 3
> MILD
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Table 5 Evaluation of conscious perception of a pulsed electric field. Subjects responses during the presence (On) and absence (Off) of the field, respectively.
ON Yes*
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32 261
No
(b)
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(a)
RESPONSE
PULSED FIELD
Figure Legend
Figure 1. Spatial distribution of the external electric field (E) in the mid-sagittal plane. E
electrically isolated (insert), and calculated at all points in the subjects environment. Average E surrounding the head was about 300 V/m.
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was generated by applying VAC = 100 volts to parallel metal plates while the subject was