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Editorial Facial Muscles: A Window to Unconsciousness The muscles of the upper face are unique. They are not classed as skeletal muscles because they move skin, not bone. Their function is not movement, per se, but com- munication. This signalling is done on two levels - con- scious voluntary and sub- or unconscious involuntary. Until the advent of technologically orientedmedicine, physicians since antiquity relied heavily on this form of communication during bedside diagnosis. It was important to carefully observe how a patient spoke as well as to listen to what was said. Modern medicine, particularly in the surgical and critical care environments, may seem to be incompatiblewith this approach. However, nothingcould be further from the truth. For the past decade, my colleaguesand I have used simple electrophysiologic monitoring to maintain low level com- munication with sleeping, anesthetized and comatose pa- tients (1-2). Communication with unconscious or seemingly unre- sponsive patients is often possible because of the special characteristics engendered in the upper facial muscles. These muscles emerge embryologically from the gill slits and are thus often classed as viscera. Their autonomic origin emphasizes that their primary role is the communica- tion of strong emotion. Increasedsympathetic tone signify- ing the classic fight or flight reaction is manifested by increased activity of the vigilance/surprise muscle, the frontalis. Strong negativeemotionssuch as anger preferen- tially contract its antagonist, the procerus. The painful grimace is largelydue to orbicularisocculi and zygomaticus contractions (2). Surface electromyographic (EMG) record- ingscan quantifythese subtle displays even in patientswho are chemically paralyzed, since the upper facial muscles are quite resistantto neuromuscular blocking drugs (3-4). Sleep Polysomnography seeks to measure sleep-wakefulness patterns through polygraphic recordings of a variety of physiologic functions. Rechtshaffen and Kales (5) recom- mend that a minimally satisfactory recordingshould include 3 channels of facial EMG/EOG and one channel of EEG: It is often not appreciatedthat the EEG alone cannot be used to reliably document the absence of consciousness. The mainstay of polysomnography is facial muscle movement not cerebrocorticalelectrical activity. In fact, we have found 8-hour histograms of a single channel of frontalis EMG to be nearly superimposable with hypnograms prepared by a polysomnographer (1). Sleep disruptionand deprivation are often unrecognized factors contributingto the disorientation that may complicate or prolong a hospital stay. Continuous single channel facial EMG recording helps an alert staff to promote healthy patient sleep patterns by adjustment of nursing routine. Awareness One of the goals of chemical sleep, or anesthesia, is to renderthepatientunconscious. That is, the level of vigilance has been reduced so that the patient is unaware of, and unresponsive to, environmental change. The polypharmacy inherent in modern anesthetic techniques creates the oppor- tunity for inadequately diminished vigilance in the face of chemical paralysis. Such intraoperative awarenesscan have catastrophic psychological consequences (6). Several inter- national conferences dedicated to this topic testify to its widespread recognition (7). If one views vigilanceas acontinuum, its nadir is complete unawareness. By definition, this state can be measured by a total lack of responsiveness. Sudden increases in facial EMG following either surgical stimulation or conversation with the patient document responsiveness, the necessary hallmark of intraoperative awareness (8-1 0). To illustrate this point, we usedthe Stagnara wake-up test during scoliosis surgery to characterize the physiologic changes accompa- nying brief periods of increasedvigilance (I 1 ). After correc- tion of the spinal deformity, anesthetic and relaxant were temporarily discontinuedand the patientwas asked to move both legs. Patient responsiveness demonstrated at least partialawareness, but pain was generallynot perceived and postoperative conscious recall for the experience did not occur, Heartrate, blood pressure, EEG mean frequency and upper facial EMG were continuously recorded during the entire surgery. Of these measures, only the EMG reliably predicted patient movement. lnterpatientvariability in each of the other measures was so large that the vigilance increase for a single patient could not be confidently deter- mined. Pain Another goal of effective anesthesia is analgesia, the block- ade of pain sensation. Obstetrical labor provides an oppor- tunity to examine both the physiologic correlates of intense acute pain without the confounding influence of general anesthesia. We compared the relationship of three meas- uresof sympathetictone(heart rate,pulse plethysmographic amplitude and upper facial EMG amplitude) and the patient subjective pain score in response to powerful uterine con- tractions (1 2). After removing recording segments in which the facial muscles had been used for voluntary communica- tion, a near-perfect correlation between the magnitude of uterine and facial muscle contractionwas observed initially. The relationship was disrupted only after the administration of effectivelevels of epidural anesthesia. There was far less agreement with either the heart rate or pulse amplitude. Thus, the EMG can provide an objective index of epidural anesthetic adequacy and maximize safety by establishing the lowest possible efficacious dose. 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Editorial

Facial Muscles: A Window to Unconsciousness

The muscles of the upper face are unique. They are not classed as skeletal muscles because they move skin, not bone. Their function is not movement, per se, but com- munication. This signalling is done on two levels - con- scious voluntary and sub- or unconscious involuntary. Until the advent of technologically oriented medicine, physicians since antiquity relied heavily on this form of communication during bedside diagnosis. It was important to carefully observe how a patient spoke as well as to listen to what was said.

Modern medicine, particularly in the surgical and critical care environments, may seem to be incompatible with this approach. However, nothing could be further from the truth. For the past decade, my colleagues and I have used simple electrophysiologic monitoring to maintain low level com- munication with sleeping, anesthetized and comatose pa- tients (1-2).

Communication with unconscious or seemingly unre- sponsive patients is often possible because of the special characteristics engendered in the upper facial muscles. These muscles emerge embryologically from the gill slits and are thus often classed as viscera. Their autonomic origin emphasizes that their primary role is the communica- tion of strong emotion. Increased sympathetic tone signify- ing the classic fight or flight reaction is manifested by increased activity of the vigilance/surprise muscle, the frontalis. Strong negative emotions such as anger preferen- tially contract its antagonist, the procerus. The painful grimace is largely due to orbicularis occuli and zygomaticus contractions (2). Surface electromyographic (EMG) record- ings can quantify these subtle displays even in patients who are chemically paralyzed, since the upper facial muscles are quite resistant to neuromuscular blocking drugs (3-4) .

Sleep

Polysomnography seeks to measure sleep-wakefulness patterns through polygraphic recordings of a variety of physiologic functions. Rechtshaffen and Kales (5) recom- mend that a minimally satisfactory recording should include 3 channels of facial EMG/EOG and one channel of EEG: It is often not appreciated that the EEG alone cannot be used to reliably document the absence of consciousness. The mainstay of polysomnography is facial muscle movement not cerebrocortical electrical activity. In fact, we have found 8-hour histograms of a single channel of frontalis EMG to be nearly superimposable with hypnograms prepared by a polysomnographer (1). Sleep disruption and deprivation are often unrecognized factors contributing to the disorientation that may complicate or prolong a hospital stay. Continuous single channel facial EMG recording helps an alert staff to promote healthy patient sleep patterns by adjustment of nursing routine.

Awareness

One of the goals of chemical sleep, or anesthesia, is to renderthe patient unconscious. That is, the level of vigilance has been reduced so that the patient is unaware of, and unresponsive to, environmental change. The polypharmacy inherent in modern anesthetic techniques creates the oppor- tunity for inadequately diminished vigilance in the face of chemical paralysis. Such intraoperative awareness can have catastrophic psychological consequences (6). Several inter- national conferences dedicated to this topic testify to its widespread recognition (7).

If one views vigilance as acontinuum, its nadir is complete unawareness. By definition, this state can be measured by a total lack of responsiveness. Sudden increases in facial EMG following either surgical stimulation or conversation with the patient document responsiveness, the necessary hallmark of intraoperative awareness (8-1 0). To illustrate this point, we used the Stagnara wake-up test during scoliosis surgery to characterize the physiologic changes accompa- nying brief periods of increased vigilance (I 1 ). After correc- tion of the spinal deformity, anesthetic and relaxant were temporarily discontinued and the patient was asked to move both legs. Patient responsiveness demonstrated at least partial awareness, but pain was generally not perceived and postoperative conscious recall for the experience did not occur, Heart rate, blood pressure, EEG mean frequency and upper facial EMG were continuously recorded during the entire surgery. Of these measures, only the EMG reliably predicted patient movement. lnterpatient variability in each of the other measures was so large that the vigilance increase for a single patient could not be confidently deter- mined.

Pain Another goal of effective anesthesia is analgesia, the block- ade of pain sensation. Obstetrical labor provides an oppor- tunity to examine both the physiologic correlates of intense acute pain without the confounding influence of general anesthesia. We compared the relationship of three meas- uresof sympathetictone (heart rate, pulse plethysmographic amplitude and upper facial EMG amplitude) and the patient subjective pain score in response to powerful uterine con- tractions (1 2). After removing recording segments in which the facial muscles had been used for voluntary communica- tion, a near-perfect correlation between the magnitude of uterine and facial muscle contraction was observed initially. The relationship was disrupted only after the administration of effective levels of epidural anesthesia. There was far less agreement with either the heart rate or pulse amplitude. Thus, the EMG can provide an objective index of epidural anesthetic adequacy and maximize safety by establishing the lowest possible efficacious dose.

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Page 2: Facial Muscles: A Window to Unconsciousness

78 Edmonds

Coma

As we approach the twenty first century, it seems inconceiv- able that assessment of patient responsiveness during coma may rely solely on hourly determination of the Glas- gow Coma Score. Continuous facial EMG monitoring often shows marked change in a patient’s reactivity to nursing procedures and family visitation even though a non-varying score of three is taken by the physician to mean a complete loss of responsiveness (13). In assessing either the depth of anesthesia or coma it is often not appreciated that the strongest activating stimuli are not somatosensory but auditory. Meaningful verbal messages with an emotional content can initiate facial movement in patients who are totally unresponsive to presentation of intensely painful stimuli. Analysis of 24 hour facial EMG recordings are important in patient management because they provide a continuous objective measurement of responsiveness. This information can be used to guide administration of sedatives and anesthetics. In addition, improvements in nursing care can be made minimizing stress and creating an atmosphere designed to promote re-establishment of normal sleep - wakefulness patterns.

It is concluded that facial muscle monitoring improves patient care because it emphasizes a wholistic approach. This technology, in contrast to most others, enhances appreciation of the patient’s underlying emotional state. Such knowledge is vital in achieving optimal therapeutic success.

Harvey L Edmonds Jr, Ph.D. Department of Anesthesiology University of Louisville Louisville, Kentucky 40292 USA

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References Edmonds HL Jr, Paloheimo M, Wauquier A. Compuferized EMG rnoniforinu. Weert. the Netherlands: Malherbe Publish- ing Group, 1986. Paloheimo M. Quantitative surface electromvoaraohv laEMG1:

I , . . . applications in anesthesiology and critical care. Acia Anaesthesiol Scand 1990; 34 (Suppl93). Paloheimo M, Wilson RC, Edmonds HL Jr, Lucas LF, Triantafillou AN. Comparison of neuromuscular blockade in upper facial and hypothenar muscles. J Clin Monif 1988; 4: 256-60. Paloheimo M, Edmonds HL Jr, Wirtavuori K, Tammisto T. Assessment of anaesthetic adequacy with upper facial and abdominal wall EMG. Eur J Anaesthesioll989; 6: 11 1-19. Rechtschaffen A, Kales A. A manual of standardized fermi- nology, techniques and scoring system for sleep stages of human subjects. Washington, DC: The US Government Print- ing Office, 1968. Guerra F. Awareness and recall. lnt Anesthesiol Clin 1986; 24: 75-99. Rosen M, Lunn JN, eds. Consciousness, Awareness and Pain in General Anaesthesia. London: Butterworths, 1987. Couture LJ, Edmonds HL Jr. Monitoring responsiveness during anaesthesia. Bailliere’s Clin Anaesthesiol 1989; 3:

Edmonds HL Jr, Smith NT. Monitoring the adequacy of opioid anesthesia. In: Estafanous FG, ed. Opioids in Anesthesia /I. Stoneham, MA: Butterworths, 1990: 151-63. Edmonds HL Jr, Paloheimo M. Intra-operative monitoring of awareness. In: Kay B, ed. Total lntravenous Anaesthesia. Amsterdam: Elsevier, 1991 : 187-203. Couture W, Greenwald 6, Edmonds, HL Jr. Detection of responsiveness during intravenous anesthesia. In: Bonke K, ed. memoryandawarenessinanaesthesia. Amsterdam: Swetz & Zeitlinger, 1991 (in press). Cases-Cristobal VC, Ackerman WE, Edmonds HL Jr, Juneja MM, Bellinger K, Rigor BM. Objective assessment of partu- rient pain using upper facial electromyography (FEMG). froc Am SOC Reg Anesfh 1992: (in press). Edmonds HL Jr, Stolzy SL, Couture LJ: Surface electromyography during low vigilance states. In: Rosen M, Lunn JN, eds. Consciousness, awareness andpain in general anaesfhesia. London: Butterworths, 1987: 89-98.

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