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Confirmation of Babinski-like response in periodic movements in sleep (nocturnal myoclonus)
BIOL PSYCHIATRY 1987;22:1271-1273
1271
BRIEF REPORTS
Confirmation of Babinski-Like Response in Periodic Movements in Sleep (Nocturnal Myoclonus) Robert C. Smith
Introduction Periodic movements in sleep (PMS), also called nocturnal myoclonus, is a disorder of unknown etiology (Coleman 1982). It has been reported in association with many sleep disorders and has also been observed in asymptomatic persons (Bixler et al. 1978; Coleman et al. 1980). It is of importance clinically because it is responsible for 12% of all cases of insomnia (Coleman et al. 1982). The foot and leg movements in PMS are characterized by dorsiflexion of the ankle, extension of the great toe, extension and fanning of the small toes, and partial flexion of the knee and hip (Guilleminauh et al. 1975; Coleman et al. 1980; Smith 198.5); clonic movements about the ankle and toes have also been described (Lugaresi et al. 1968; Smith 1985). As these movements closely resemble the clinical Babinski response (Smith 198.5) and as PMS (Coleman 1982) and the normally occurring nocturnal Babinski response (Fujiki et al. 1971) are phenomena of NREM sleep, the author recently proposed that the foot and leg movements of PMS are Babinski-like responses due to changes in the pyramidal tracts during NREM sleep (Smith 1985). The conclusion that these foot and leg move-
From the Sleep Dwxders Center, St. Louis University. St. Lows. MO. and the Sleep Disorders Center, @ham Medical Center, Michigan State University, East Lansing, MI. Address reprint requests to Dr. R. C. Smith, B220 Life Sciences Bldg., Departments of Medicine and Psychiatry. Michigan State University, East Lansing, MI 48824. Received and revised February 26, 1987.
0 19X7 Society 01 Biologxal
Psychiatry
ments resembled Babinski responses was based on the author’s detailed, frame-by-frame videographic analysis of nine patients with documented PMS. This article reports the results of independent rating of the same foot and leg movements by 23 physicians from the primary care. pulmonary, physiatry, and neurology dimensions of medicine. Following only a single, brief observation of the movements on videotape, they identified them as resembling a Babinski response in 43% of the movements rated.
Methods As detailed in the initial report (Smith 1985), all patients were studied under standard conditions by polysomnography and had documented PMS. Videographic study was performed with a video camera in the patient’s room that was controlled by a technician in an adjacent room. The videotape recorder and the polysomnographic equipment were also in the technician’s room. The first 11 foot and leg movements of each of 9 patients were evaluated by the author from original videotapes in the initial study. For the present study, these same 99 foot and leg movements were randomized, with equal representation of each patient, for evaluation by independent raters. Because of time constraints on the raters, only the first 45 movements were selected; these were transposed to a second videotape for rating purposes. Due to considerable loss of clarity in the process of transfer, the
1272
Brief Reports
BIOL PSYCHIATRY 1981;22:1271-3273
author dropped nine of the foot/leg movements as not ratable; this involved two movements from two patients and one each from five others. The author judged the remaining 36 movements as potentially ratable. Seven general internists in academic primary care, eight internists with subs~cialty training in pulmonary medicine, two physiatrists, and six neurologists were recruited to rate the videotapes. None were aware of the author’s paper or hypothesis. They were informed that they were serving as a “gold standard” to rate movements of the feet and legs in sleeping patients. The author reviewed the definition of the Babinski response with them beforehand: dorsiflexion of the great toe with fanning of the other toes, at times associated with dorsiflexion of the ankle and flexion of the knee and hip (Grinker et al. 1960). Raters were instructed to rate whether or not each of the 36 movements, without stimulation of the sole, resembled those seen with the Babinski response. Although they were not given any diagnostic information, it was apparent to them that the subjects were in a sleep laboratory setting because of the split screen display of a polysomnographic tracing on some of the videotapes. Raters were also instructed to rate the videotape as “not ratable” if it lacked sufficient clarity for them. After a brief warmup period to familiarize the raters with the videotape, all 45 movements were shown continuously in numbered sequence. The raters were instructed to ignore the 9 nonratable movements. Each vignette of foot and leg movements lasted from 10 to 1.5 set and was shown only once. The entire procedure took 20-25 min. Rating groups varied in size from one to eight persons; with the larger groups, some raters, of
Table 1. Raters’ Judgments
necessity, were required to view the videotape from greater than optimal distance.
Results The raters were all board-qualified in their respective areas and most were board-ce~ified, some in more than one discipline. Al1 are prominent in the community and most are faculty at Michigan State University. Table 1 shows raters’ judgments about the number of foot/leg movements that were ratable; this indicates some heisting problems with lack of clarity of the videotape. The percentage of movements rated as Babinski-like responses by the raters was determined by dividing the number of Babinski-like ratings by the total number of movements judged as ratable. Overall, the 23 raters rated 43% (range 19%-82%) of all ratable movements as Babinski-like responses. The 7 primary care internists rated 38% (19%-4X%) of the movements as Babinski-like; the 8 internists with pulmonary subs~~ialty interests rated 52% (3 I%-82%) as Babinski”like; the two physiatrists rated 35% (21%-50%) as Babinski-like; and the 6 neurologists rated 41% (21%-61%) as Babinski-like.
Discussion This study showed that experienced physicians from several different disciplines consistently agreed with the author’s initial interpretation that the foot/leg movements in PMS resemble the Babinski response (Smith 1985). The 43% rate of agreement is considerably higher than the author had anticipated. Initially, some of the movements were apparent to the author only with detailed, frame-by-frame videographic
of Ratable Foot/Leg Movements No. of
No. of movements judged ratable
raters (II =
23)
6-10
11-15
16-20
2
4
12
21-23
(n = 36) 18
Brief Reports
BiOt PSYCHIATRY 1987:22:1271-1273
1273
of its analysis should be, in the author’s opinion, analysis and were believed to be appreciable neurophysiological investigation. only by that technique. The results reported here indicate that nearly half of the movements are discernable as Bab~nski-like responses du~ng a The author thanks Janice Weiss, Jeff Sevier. Janice Hersingle, brief observation. This is all the more mann, Sherry Smalley, and Frank Muriel for their tireless remarkable in view of the reduced quality of the assistance. advice, md support. videotape seen by the raters and by the fact that some raters viewed the videotape under less than optimal conditions. References The loss of cases due to lack of darity of the Bixier E, Soldatos R. Scarone S. Martin E. Kales A. videotape is troublesome and represents the maChamey D (1978): Similarities of nocturnal myjor shortcoming of this study. In the future, more oclonic activity in insomniac patients and normal subjects. Sleep Res 71213. attention will be required with respect to equipColeman RM (1982): Periodic movements in sleep ment and technique; it appears that what is sat(nocturnal myocionus) and restless legs synisfactory for routine clinical purposes may not drome. In GuilIeminau~t C (ed), Sleeping und be appropriate for the more refined needs of Waking Disorders: Indications and Techniques. rating, particularly when transfer of material to Menlo Park, CA: Addison-Wesley. 265-295. a second videotape is required. Coleman RM, Pollack C, Weitzman ED (1980): PeThe significance of this study was that it proriodic movements in sleep (nocturnal myoclonus): vided independent confirmation of the author’s Relation to sleep--wake disorders. Am Neurol 8416-421. initial observation that the foot and leg moveColeman RM , Roffwarg HP, Kennedy SJ. et al ( 1982): ments of PMS resemble the clinical Babinski Sleep-wake disorders based on a polysomnoresponse (Smith 1985). Based on this obsergraphic diagnosis. JAMA 247:997-1003. vation, the author proposed that the foot/leg Fujiki A, Shimizu A, Yamada Y. Yamamoto J, Kamovements of PMS, which occur almost enneko Z (1971): The Babinski reflex during sleep tirely in NREM (Coleman 1982), are due to loss and wakefulness. Electroencepj~ Clin ~eur~~ph~of supraspinal inhibition of the pyramidal tracts siol31:610-613. during NREM (Smith 1985). In support of this Grinker RR, Bucy PC, Sahs AL (1960): Neurology. Springfield. IL: Charles C Thomas. p. 42. was the earlier observation of Fujiki et al. ( 197 1) that stroking the foot of normals elicited a Ba- Guilleminault C, Raynal D, Weitzman ED, Dement WC (1975): Sleep-related periodic myoclonus in binski response in one-half during NREM, but patients compl~ning of insomnia. 7’rnn.sAm Nrurarely during REM. Further support for the hyrof Assoc 100:19-22. pothesis comes from the recent demonstration Lugaresi E. Coccagna G, Bert-Ceroni G. Ambroby Mosko and Nudleman (1986) that somatosetto C (1968): Restless legs syndrome and nocsensory and brain stem auditory evoked returnal myoclonus. In Gastaut H, Lugaresi E. Bertisponses are normal in patients with PMS. This Ceroni G, Coccagna G (eds), The Abnormalities indicated to them that the abnormality in PMS of Sleep in Mm: Proceedings of the 15th European Meetirtg on Electtoeneephulo~raI?hv, Bowas not due to an afferent sensory disturbance lugs. 1967. Bologna: Au10 Gaggi Editore, pp and that it was more likely due to dysfunction 285-294. in the descending motor system (Mosko and Mosko SS, Nudleman KL ( 1986): Somatosensory and Nuddleman 1986). brainstem auditory evoked responses in sleep-rcThe independent corroboration of the aulated periodic leg movements. Sleep 9:399-404. thor’s initial observation represents the second Smith RC (1985): ReIationship of periodic movestage of development of the hypothesis. With ments in sleep (noctumai myocIonus) and the Bathis support for the hypothesis, the next phase binski sign. Sleep 8239-243.
1271
BRIEF REPORTS
Confirmation of Babinski-Like Response in Periodic Movements in Sleep (Nocturnal Myoclonus) Robert C. Smith
Introduction Periodic movements in sleep (PMS), also called nocturnal myoclonus, is a disorder of unknown etiology (Coleman 1982). It has been reported in association with many sleep disorders and has also been observed in asymptomatic persons (Bixler et al. 1978; Coleman et al. 1980). It is of importance clinically because it is responsible for 12% of all cases of insomnia (Coleman et al. 1982). The foot and leg movements in PMS are characterized by dorsiflexion of the ankle, extension of the great toe, extension and fanning of the small toes, and partial flexion of the knee and hip (Guilleminauh et al. 1975; Coleman et al. 1980; Smith 198.5); clonic movements about the ankle and toes have also been described (Lugaresi et al. 1968; Smith 1985). As these movements closely resemble the clinical Babinski response (Smith 198.5) and as PMS (Coleman 1982) and the normally occurring nocturnal Babinski response (Fujiki et al. 1971) are phenomena of NREM sleep, the author recently proposed that the foot and leg movements of PMS are Babinski-like responses due to changes in the pyramidal tracts during NREM sleep (Smith 1985). The conclusion that these foot and leg move-
From the Sleep Dwxders Center, St. Louis University. St. Lows. MO. and the Sleep Disorders Center, @ham Medical Center, Michigan State University, East Lansing, MI. Address reprint requests to Dr. R. C. Smith, B220 Life Sciences Bldg., Departments of Medicine and Psychiatry. Michigan State University, East Lansing, MI 48824. Received and revised February 26, 1987.
0 19X7 Society 01 Biologxal
Psychiatry
ments resembled Babinski responses was based on the author’s detailed, frame-by-frame videographic analysis of nine patients with documented PMS. This article reports the results of independent rating of the same foot and leg movements by 23 physicians from the primary care. pulmonary, physiatry, and neurology dimensions of medicine. Following only a single, brief observation of the movements on videotape, they identified them as resembling a Babinski response in 43% of the movements rated.
Methods As detailed in the initial report (Smith 1985), all patients were studied under standard conditions by polysomnography and had documented PMS. Videographic study was performed with a video camera in the patient’s room that was controlled by a technician in an adjacent room. The videotape recorder and the polysomnographic equipment were also in the technician’s room. The first 11 foot and leg movements of each of 9 patients were evaluated by the author from original videotapes in the initial study. For the present study, these same 99 foot and leg movements were randomized, with equal representation of each patient, for evaluation by independent raters. Because of time constraints on the raters, only the first 45 movements were selected; these were transposed to a second videotape for rating purposes. Due to considerable loss of clarity in the process of transfer, the
1272
Brief Reports
BIOL PSYCHIATRY 1981;22:1271-3273
author dropped nine of the foot/leg movements as not ratable; this involved two movements from two patients and one each from five others. The author judged the remaining 36 movements as potentially ratable. Seven general internists in academic primary care, eight internists with subs~cialty training in pulmonary medicine, two physiatrists, and six neurologists were recruited to rate the videotapes. None were aware of the author’s paper or hypothesis. They were informed that they were serving as a “gold standard” to rate movements of the feet and legs in sleeping patients. The author reviewed the definition of the Babinski response with them beforehand: dorsiflexion of the great toe with fanning of the other toes, at times associated with dorsiflexion of the ankle and flexion of the knee and hip (Grinker et al. 1960). Raters were instructed to rate whether or not each of the 36 movements, without stimulation of the sole, resembled those seen with the Babinski response. Although they were not given any diagnostic information, it was apparent to them that the subjects were in a sleep laboratory setting because of the split screen display of a polysomnographic tracing on some of the videotapes. Raters were also instructed to rate the videotape as “not ratable” if it lacked sufficient clarity for them. After a brief warmup period to familiarize the raters with the videotape, all 45 movements were shown continuously in numbered sequence. The raters were instructed to ignore the 9 nonratable movements. Each vignette of foot and leg movements lasted from 10 to 1.5 set and was shown only once. The entire procedure took 20-25 min. Rating groups varied in size from one to eight persons; with the larger groups, some raters, of
Table 1. Raters’ Judgments
necessity, were required to view the videotape from greater than optimal distance.
Results The raters were all board-qualified in their respective areas and most were board-ce~ified, some in more than one discipline. Al1 are prominent in the community and most are faculty at Michigan State University. Table 1 shows raters’ judgments about the number of foot/leg movements that were ratable; this indicates some heisting problems with lack of clarity of the videotape. The percentage of movements rated as Babinski-like responses by the raters was determined by dividing the number of Babinski-like ratings by the total number of movements judged as ratable. Overall, the 23 raters rated 43% (range 19%-82%) of all ratable movements as Babinski-like responses. The 7 primary care internists rated 38% (19%-4X%) of the movements as Babinski-like; the 8 internists with pulmonary subs~~ialty interests rated 52% (3 I%-82%) as Babinski”like; the two physiatrists rated 35% (21%-50%) as Babinski-like; and the 6 neurologists rated 41% (21%-61%) as Babinski-like.
Discussion This study showed that experienced physicians from several different disciplines consistently agreed with the author’s initial interpretation that the foot/leg movements in PMS resemble the Babinski response (Smith 1985). The 43% rate of agreement is considerably higher than the author had anticipated. Initially, some of the movements were apparent to the author only with detailed, frame-by-frame videographic
of Ratable Foot/Leg Movements No. of
No. of movements judged ratable
raters (II =
23)
6-10
11-15
16-20
2
4
12
21-23
(n = 36) 18
Brief Reports
BiOt PSYCHIATRY 1987:22:1271-1273
1273
of its analysis should be, in the author’s opinion, analysis and were believed to be appreciable neurophysiological investigation. only by that technique. The results reported here indicate that nearly half of the movements are discernable as Bab~nski-like responses du~ng a The author thanks Janice Weiss, Jeff Sevier. Janice Hersingle, brief observation. This is all the more mann, Sherry Smalley, and Frank Muriel for their tireless remarkable in view of the reduced quality of the assistance. advice, md support. videotape seen by the raters and by the fact that some raters viewed the videotape under less than optimal conditions. References The loss of cases due to lack of darity of the Bixier E, Soldatos R. Scarone S. Martin E. Kales A. videotape is troublesome and represents the maChamey D (1978): Similarities of nocturnal myjor shortcoming of this study. In the future, more oclonic activity in insomniac patients and normal subjects. Sleep Res 71213. attention will be required with respect to equipColeman RM (1982): Periodic movements in sleep ment and technique; it appears that what is sat(nocturnal myocionus) and restless legs synisfactory for routine clinical purposes may not drome. In GuilIeminau~t C (ed), Sleeping und be appropriate for the more refined needs of Waking Disorders: Indications and Techniques. rating, particularly when transfer of material to Menlo Park, CA: Addison-Wesley. 265-295. a second videotape is required. Coleman RM, Pollack C, Weitzman ED (1980): PeThe significance of this study was that it proriodic movements in sleep (nocturnal myoclonus): vided independent confirmation of the author’s Relation to sleep--wake disorders. Am Neurol 8416-421. initial observation that the foot and leg moveColeman RM , Roffwarg HP, Kennedy SJ. et al ( 1982): ments of PMS resemble the clinical Babinski Sleep-wake disorders based on a polysomnoresponse (Smith 1985). Based on this obsergraphic diagnosis. JAMA 247:997-1003. vation, the author proposed that the foot/leg Fujiki A, Shimizu A, Yamada Y. Yamamoto J, Kamovements of PMS, which occur almost enneko Z (1971): The Babinski reflex during sleep tirely in NREM (Coleman 1982), are due to loss and wakefulness. Electroencepj~ Clin ~eur~~ph~of supraspinal inhibition of the pyramidal tracts siol31:610-613. during NREM (Smith 1985). In support of this Grinker RR, Bucy PC, Sahs AL (1960): Neurology. Springfield. IL: Charles C Thomas. p. 42. was the earlier observation of Fujiki et al. ( 197 1) that stroking the foot of normals elicited a Ba- Guilleminault C, Raynal D, Weitzman ED, Dement WC (1975): Sleep-related periodic myoclonus in binski response in one-half during NREM, but patients compl~ning of insomnia. 7’rnn.sAm Nrurarely during REM. Further support for the hyrof Assoc 100:19-22. pothesis comes from the recent demonstration Lugaresi E. Coccagna G, Bert-Ceroni G. Ambroby Mosko and Nudleman (1986) that somatosetto C (1968): Restless legs syndrome and nocsensory and brain stem auditory evoked returnal myoclonus. In Gastaut H, Lugaresi E. Bertisponses are normal in patients with PMS. This Ceroni G, Coccagna G (eds), The Abnormalities indicated to them that the abnormality in PMS of Sleep in Mm: Proceedings of the 15th European Meetirtg on Electtoeneephulo~raI?hv, Bowas not due to an afferent sensory disturbance lugs. 1967. Bologna: Au10 Gaggi Editore, pp and that it was more likely due to dysfunction 285-294. in the descending motor system (Mosko and Mosko SS, Nudleman KL ( 1986): Somatosensory and Nuddleman 1986). brainstem auditory evoked responses in sleep-rcThe independent corroboration of the aulated periodic leg movements. Sleep 9:399-404. thor’s initial observation represents the second Smith RC (1985): ReIationship of periodic movestage of development of the hypothesis. With ments in sleep (noctumai myocIonus) and the Bathis support for the hypothesis, the next phase binski sign. Sleep 8239-243.