American Journal of Perinatology VOLUME 9

NUMBER 1

JANUARY 1992

ABSENT FETAL MOVEMENT RESPONSE WITH A BLUNTED CARDIOACCELERATORY FETAL RESPONSE TO EXTERNAL VIBRATORY ACOUSTIC STIMULATION IN A FETUS WITH THE PENA-SHOKEIR SYNDROME (FETAL AKINESIA AND HYPOKINESIA SEQUENCE)

ABSTRACT We present a case that describes a partial fetal response to external vibratory acoustic stimulation in that, although no fetal movements were elicited, a blunted, brief positive cardioacceleratory response was noted. This fetus exhibited features of the PenaShokeir syndrome, characterized by skeletal neurogenic atrophy, yet with a normal auditory system at autopsy. This observation may suggest that the prolonged increase in the basal fetal heart noted after fetal vibratory acoustic stimulation is sustained by active fetal movements, absent in this fetus due to joint contractures.

External vibratory acoustic stimulation offers a fetal stimulatory technique and is used in cases of nonreactive nonstress tests to provoke fetal movements and fetal heart rate accelerations in the third trimester. The main advantages of external vibratory acoustic stimulation are a lowered incidence of false-positive nonreactive nonstress tests by 50% and a reduction in the required testing time.1-4 At this time, it is not completely understood whether the auditory or the tactile vibratory response accounts for the evoked fetal stimulation. The Pena-Shokeir syndrome (fetal akinesia and hypokinesia sequence) is a lethal disorder involving multiple joint contractures, facial anomalies, and pulmonary hypoplasia with an autosomal recessive mode of inheritance.5~9 Fetal movements in utero are usually absent or markedly diminished. Application of the fetal vibratory acoustic stimulation to such fetuses may add to further understanding of the

underlying physiology of the normal reactive stimulation test. We present a case in which a fetus with Pena-Shokeir syndrome, as expected, did not move after external vibratory acoustic stimulation, yet demonstrated a brief blunted cardioacceleratory response. CASE REPORT

A 26-year-old gravida 2, para 1 woman was referred to the Perinatal Center at Strong Memorial Hospital for consultation in the 31st week of gestation due to sonographic findings of polyhydramnios in conjunction with an unidentified skeletal dysplasia with multiple ankyloses (elbows, hands, knees, and feet). In her previous pregnancy she had delivered, through a classic uterine incision (due to a breech presentation), an infant who died imme-

Department of Obstetrics and Gynecology, The Division of Maternal-Fetal Medicine, and The Department of Pathology, Strong Memorial Hospital, The University of Rochester, School of Medicine and Dentistry, Rochester, New York Reprint requests: Dr. Sherer, Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Strong Memorial Hospital, Box 668, The University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642 Copyright © 1992 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.

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David M. Sherer, M.D., Stephan R. Sanko, M.D., Leon A. Metlay, M.D., and James R. Woods, Jr., M.D.

AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 9, NUMBER 1 January 1992

Figure 1. Fetal heart rate tracing during external vibratory acoustic stimulation testing disclosing blunted fetal heart acceleration response (paper speed, 3 cm/min).

sample obtained at delivery showed a pH of 7.32. The infant died within minutes after delivery with no apparent respiratory effort despite initial resuscitative measures. The patient's postoperative course was uneventful. Pathologic examination of the infant (Fig. 2) revealed asymmetrical growth retardation with multiple contractures, arthrogryposis of elbows, knees, and hips. Also noted were micrognathia, bilateral absent clavicles (present in the previous sibling), and pulmonary hypoplasia. The brain weighed 250 gm. Detailed examination of the brain,

Figure 2. A photograph of the infant with Pena-Shokeir syndrome (fetal akinesia and hypokinesia sequence). Note asymmetrical growth retardation (HC/AC ratio) and limb arthrogryposis.

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diately after delivery without respiratory effort. Postmortem examination revealed the infant to have a Pena-Shokeir phenotype with hypoplastic lungs. Although during her current pregnancy, sonographic examinations at 21 and 24 weeks were reported to be normal, she had not felt fetal movements at all throughout the gestation. Review of these sonographic examinations revealed that "decreased" fetal movement had been noted during each examination. On physical examination, her uterus, measuring 34 cm, was large for dates. Sonographic examination revealed a breech-presenting fetus with marked polyhydramnios and absent fetal movements. The biparietal diameter measured 85 mm, appropriate for 34 weeks of gestation, and the abdominal circumference measured 245 mm, appropriate for 28 weeks' gestation. The head to abdominal circumference ratio (HC/AC) was 1.27 (the mean HC/AC at 34 weeks is 1.0210). The chest circumference was 180 mm, less than the 5th percentile for 31 weeks' gestation. No fetal movements were noted throughout the sonographic examination. These findings were highly suggestive of recurrent Pena-Shokeir syndrome. At 34 weeks, the polyhydramnios became markedly increased and the patient was mildly symptomatic. At that point, concern was expressed that the previous classic scar might be prone to rupture due to increasing polyhydramnios. A fetal biophysical profile was performed, the score being 2 of 10 (points given for amniotic fluid volume only). No fetal movements, breathing, rolling, or limb extension or flexion movements were noted. At this stage, under continuous sonographic visualization, fetal vibratory acoustic stimulation was performed by applying an electronic artificial larynx (model 58, Western Electric, New York, NY: audible sounds 750-1000 mHz, vibrations between 110 and 200 Hz output) for 5 seconds to the maternal abdomen directly overlying the fetal head. No fetal movements were noted by the patient and none was seen during the simultaneous sonographic scanning. The external vibratory acoustic stimulation was then performed while recording the fetal heart rate (Cardiotocograph model 8040A, Hewlett Packard Co., Waltham, MA). A very brief fetal heart acceleration of 10 beats/min above the baseline, lasting 20 seconds, was noted. No fetal movements were noted and the baseline fetal heart rate remained at 150 beats/min (Fig. 1). The stimulation was repeated with a similar fetal response three times within 1 hour. Due to these findings, that is, a most probable recurrent lethal fetal condition with polyhydramnios at 34 weeks' gestation with a previous classic uterine scar, an Institutional Fetal Therapy Committee (consisting of perinatologists, neonatologists, a pediatric surgeon, and a representative from the Pediatric Genetics Division) recommended preterm elective cesarean delivery for maternal indications. Under spinal anesthesia through a transverse lower uterine segment incision, a female fetus weighing 1750 gm was delivered. The arterial umbilical cord

PENA-SHOKEIR SYNDROME/Sherer, et al.

DISCUSSION

The normal fetal response to the vibratory acoustic stimulation has two components: acceleration of the fetal heart and a startle response, that is, fetal movement. Acceleration of the fetal heart rate is defined as a rise in the baseline fetal heart rate in the range of 10 beats/min lasting 10 seconds3 or 14 to 25 beats/ min lasting at least 10 to 30 seconds,11 or 15 beats/ min for at least 15 seconds by other authors.12 The strictest criteria defining a fetal heart rate acceleration are an increase of at least 20 beats/min sustained for at least 2 minutes.13 It is interesting to note that although the fetus described responded with a blunted fetal heart rate acceleration, the cord arterial pH was normal, as predicted by Polzin et al.3 Following stimulation by the electronic artificial larynx, fetal heart rate accelerations have been noted to occur in association with fetal movements.1-4 This phenomenon has been attributed to activation of the sympathetic innervation of the fetal heart.14 An increase in the basal heart rate beginning immediately after vibratory acoustic stimulation and remaining elevated above control for up to 1 hour after the stimulus as well as an increase in fetal heart rate accelerations coincident with fetal movement are well documented in normal fetuses.24 A report by Ohel et al.15 of absent responses to acoustic stimulation in two anencephalic fetuses suggests the requirement of an intact fetal auditory system for this response. These authors imply that an intact reflex arc below the level of the fetal brainstem is not sufficient to produce this response and therefore suggested that the fetal reaction to vibratory acoustic stimulation is not the result of a tactile response.15 The case we present would suggest that an intact auditory system (in our case, proven by autopsy) may be sufficient on its own to obtain a positive though perhaps blunted response. Fetal movements and possible also intact tactile reflex arcs (especially the efferent arc absent here) may be prerequisites together with fetal well-being for an un-

equivocally positive fetal response to the external vibratory acoustic stimulation.16 Recently, ultrasound has been employed to monitor fetal movement during the external vibratory acoustic stimulation test.17-18 Kuhlman et al.17 noted that 100% of fetuses displayed startle responses by 28 weeks and Crade and Lovett18 noted that 96% of fetuses reacted at more than 31 weeks. ADDENDUM

Recently, a second similar case has been documented at Strong Memorial Hospital. A 28-year-old gravida 2, para 1 woman was referred to our care due to polyhydramnios and nonvisualization of the fetal stomach at 34 weeks' gestation. Sonographic examination revealed a singleton, vertex-presenting fetus with multiple ankyloses (elbows, hands, knees, and feet) with absent fetal movements (breathing, rolling, limb extension or flexion, or swallowing) noted. Under continuous sonographic visualization, fetal vibratory acoustic stimulation was performed. No fetal movements were seen. Subsequently, vibratory acoustic stimulation was performed while recording the fetal heart rate. As in the previous case, a very brief fetal heart acceleration was noted (Fig. 3). No fetal movements were noted. Despite the dismal fetal prognosis, at 37 weeks an elective cesarean section was performed at the patient's request due to the markedly increasing polyhydramnios with associated abdominal pain and mild respiratory problems. A 1620 gm female infant with Apgar scores of 1,1, and 2 at 1, 5, and 10 minutes, respectively, was delivered. The infant died at 2 hours of age due to respiratory failure despite resuscitative measures, including intubation and efforts at ventilating. Pathologic examination of the infant (Fig. 4) was consistent with the Pena-Shokeir phenotype. This second case was similar to the first in that a partial fetal response to external vibratory acoustic stimulation was noted in a fetus with the PenaShokeir phenotype, which strengthens our hypoth-

Figure 3. Fetal heart rate tracing during external vibratory acoustic stimulation of the second fetus, disclosing blunted fetal heart rate acceleration response (paper speed, 3 cm/min).

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including the auditory system and spinal cord, revealed no pathologic findings. Multiple sections at different levels of the spinal cord contained no appreciable loss of anterior horn cells and gliosis, that is, no evidence of anterior horn cell disease. Electron microscopy of skeletal muscle tissue revealed subtly increased fiber diameter variability, small myofibers with somewhat disorganized striations. These findings were all consistent with the Pena-Shokeir phenotype. The etiology of the congenital hypotonia in this case and the previous sibling also autopsied was unclear. Intrinsically abnormal myofibers or abnormal neuromuscular transmission were thought to be the most likely etiologies because other more common pathologic processes underlying the arthrogryposis were excluded.

3

Figure 4. Photograph of second infant with the PenaShokeir syndrome (fetal akinesia and hypokinesia sequence).

esis that the prolonged increase of the fetal heart rate following this stimulation is due to continuous fetal movements, absent in both these rare cases. REFERENCES

Smith CV, Phelan JP, Platt LD, et al: Fetal acoustic stimulation testing II: A randomized clinical comparison with the nonstress test. Am J Obstet Gynecol 155:131-134, 1986

January 1992

2. Gagon R, Patrick J, Foreman J, et al: Stimulation of human fetuses with sound and vibration. Am J Obstet Gynecol 155:848-851, 1986 3. Polzin GB, Blakemore KJ, Petrie RH, et al: Fetal vibroacoustic stimulation: Magnitude and duration of fetal heart accelerations as a marker of fetal health. Obstet Gynecol 72:621-626, 1988 4. Gagon R, Hunse C, Carmichael L, et al: External vibratory acoustic stimulation near term: Fetal heart rate and heart rate variability responses. Am J Obstet Gynecol 156:323327,1987 5. Pena SDJ, Shokeir MHK: Syndrome of camptodactyly, multiple akyloses, facial anomalies and pulmonary hypoplasia: A lethal condition. J Pediatr 85:373-375, 1974 6. Jones KL: In Smith's Recognizable Patterns of Human Malformation, 4th ed. Philadelphia: WB Saunders, 1988, pp 145-146 7. McMillan RH, Harbert GM, Davis WD, et al: Prenatal diagnosis of Pena-Shokeir syndrome, type 1. J Med Genet 21: 279-284, 1985 8. Toriello HV, Bauerman SC, Higgins JV: Sibs with the fetal akinesia sequence. Fetal edema and malformations: A new syndrome? Am J Med Genet 21:271-277, 1985 9. Cardwell MS: Pena Shokeir syndrome prenatal diagnosis by ultrasonography. J Ultrasound Med 6:619-621, 1987 10. Hadlock FP, Deter RL, Harrist RB: Sonographic detection of fetal intrauterine growth retardation. Appl Radiol 12: 28-32, 1983 11. Weingold AB, Yonekura ML, O'Kieffe J: Nonstress testing. Am J Obstet Gynecol 128:195, 1980 12. Rabinowitz R, Persitz E, Sadovsky E: The relation between fetal heart accelerations and fetal movements. Obstet Gynecol 61:16-18, 1983 13. Ron M, Polishuk WZ: The response of fetal heart rate to amniocentesis. Br J Obstet Gynecol 83:768-770, 1976 14. Martin CB: Regulation of the fetal heart rate and genesis of FHR patterns. Semin Perinatol 2:131-146, 1978 15. Ohel G, Simon A, Linder N, et al: Anencephaly and the nature of fetal response to vibroacoustic stimulation. Am J Perinatol 3:345-346, 1986 16. Guyton AC: Basic human neurophysiology, ed. 3. Philadelphia: WB Saunders, 1981, pp 70-71 17. Kuhlman KA, Burns KA, Depp R, et al: Ultrasonic imaging of normal fetal response to external vibratory acoustic stimulation. Am J Obstet Gynecol 158:47-51, 1988 18. Crade M, Lovett S: Fetal response to sound stimulation: Preliminary report exploring use of sound stimulation in routine obstetrical ultrasound examinations. J Ultrasound Med 7:499-503, 1988

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AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 9, NUMBER 1

Absent fetal movement response with a blunted cardioacceleratory fetal response to external vibratory acoustic stimulation in a fetus with the Pena-Shokeir syndrome (fetal akinesia and hypokinesia sequence).

We present a case that describes a partial fetal response to external vibratory acoustic stimulation in that, although no fetal movements were elicite...
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