DIAGNOSIS
A Pulsed Transilluminator for the Infant Cranium Detection of Abnormal Transillumination Patterns Patricia W. Hayden, M.D.,* Curtis C. Johnson, Ph.D.,† Vishnu Gupta, M.D.**
THE
PATTERNS of transillumination of infant’s cranium obtained with a flashlight in a darkened room can help to demonstrate such serious lesions as hydrocephalus, cerebral atrophy, brain cysts, or subdural hydromas.l=~ This simple nontraumatic technique is often neglected, however, because time is required for dark adaptation and it yields only qualitative information. We here describe a new pulsed transilluminator which has been clinically tested on normal newborns, prematurely born infants, and some older infants with whom a question of an intracranial lesion obtained.
the
Description of
the Instrument
The instrument contains a gallium arsenide infrared-emitting diode and a silicon photodetector diode spaced three centimeters apart.’-5 The light emitter and detector are built into one hand-held unit which can be placed firmly on the infant’s head (Fig. 1). This work was underwritten in part by the National Foundation-March of Dimes and The National Institutes of Health Grants #16436 and #5 P01 HD 02774. * Associate Professor, Division of Congenital Defects, Department of Pediatrics, University of Washington School of Medicine, Seattle, Wash. 98195. &dag er; Professor of Bioengineering, University ofUtah, Salt Lake City, Utah 84112. ** Center for Bioengineering, Univerity of Utah. Correspondence to Patricia W. Hayden, M.D., Department of Pediatrics, University of Washington School of Medicine, Seattle, Wash. 98195.
An oscillator
triggers
a
15-ampere pulse
to
the emitter and activates a sample-hold circuit to read peak pulse height. The pulsed light diffuses in and is absorbed by the cranial structures in direct relation to their optical density. A meter is calibrated to read the transmitted infrared intensity in optical density units per centimeter (O.D./cm). Thus, areas filled with clear fluid will absorb less light to give lower optical density read-
ings. Results Data have been obtained from 222 normal infants. Among those were 160 normal-term infants who had transilluminator readings taken from the right and left occipital, parietal, and frontal areas. A consistent relationship existed between the occipital and frontal areas, the frontal invariably measuring at least 0.1 O.D./cm less than the occipital area. The transillumination was symmetrical, the corresponding readings from the two sides of the head not differing more than 0.1 O.D./cm. The optical density readings from the frontal areas showed a range of 1.2 to 1.9 O.D./cm (Fig. 2) with a mean of 1.58 and a standard deviation of 0.13. Little correlation to birth weight
existed (r
.03). Sixty-two premature infants showed fron-
tal to
=
optical density readings ranging from 1.2 1.8 with a mean of 1.46 (Fig. 3). Again, 627
Downloaded from cpj.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 14, 2015
FiG. 1. Pulsed transilluminator: prototype
developed
there was little correlation with birth weight or head circumference but some correlation (r .61) with gestational age in that those more prematurely born transilluminated to a =
greater degree. The factor of skin pigmentation interferwith the light reading was considered and measurements of reflected light were taken from the first 50 patients in the study. The differences proved to be insignificant in all except the few (n 7) black babies available for study. These babies invariably gave optical density readings 0.1 to 0.2 greater than the mean for nonblack babies but otherwise showed the same relationships in that the frontal areas transilluminated more than the occipital and the transillumination was symmetrical from side to side. In addition to the 222 normal newborns and prematures, 59 patients were referred for transillumination because of some question of an intracranial lesion. These varied in age from newborn to five years. Examination
ing
=
at
Center for
Bioengineering, University
of
Washington.
of these patients required scanning over all areas of the skull, searching for asymmetry or unexpected areas of decreased or increased density. After data from the pulsed transilluminator examination were recorded, each infant was subjected to standard flashlight transillumination (Table 1). Seven prematurely born babies with very low optical density readings were transilluminated at weekly intervals and showed O.D. readings increasing with age. A caput succedaneum will cause a well-circumscribed area of decreased density, whereas a cephalohematoma gives optical density readings greater than 2.0. Six infants older than one week of age with optical density readings less than 1.3 subsequently were proven to have hydrocephalus by ventriculography. Four patients with localized areas of decreased density were shown by other examinations and subsequent surgery to have cysts in the area of increased transill u mi nation. With one infant it was possible by serial
628
Downloaded from cpj.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 14, 2015
FIG. 2. Frequency distribution of optical density readings obtained from 160 normal-term infants examined during the first three days of life (see text).
transilluminator examinations to follow the resolution of -a subdural hematoma complicating hydrocephalus associated with spina bifida. Discussion Even
the
most
modern, well-equipped
nursery seldom has an adequate area which can be sufficiently darkened to do a reliable clinical transillumination. The three to five minutes required for good dark adaptation
several times longer when a squirming is baby being held in a crowded closet. Nevertheless, the significance of the lesions which transillumination may reveal makes it imperative that this procedure not be omitted from the complete examination of the newborn. The instrument described in this paper can be used in ambient room light and provides quantitative data not dependent on (Continued on page 632)
seems
FIG. 3. Frequency distribution of optical density readings obtained from 62 prematurely bom infants. These babies were considered normal with respect to head growth,
neurologic development,
and flashlight transillumination (see text).
629
Downloaded from cpj.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 14, 2015
A Pulsed Transilluminator for the Infant Cranium Detection of Abnormal Transillumination Patterns Patricia W. Hayden, M.D.,* Curtis C. Johnson, Ph.D.,† Vishnu Gupta, M.D.**
THE
PATTERNS of transillumination of infant’s cranium obtained with a flashlight in a darkened room can help to demonstrate such serious lesions as hydrocephalus, cerebral atrophy, brain cysts, or subdural hydromas.l=~ This simple nontraumatic technique is often neglected, however, because time is required for dark adaptation and it yields only qualitative information. We here describe a new pulsed transilluminator which has been clinically tested on normal newborns, prematurely born infants, and some older infants with whom a question of an intracranial lesion obtained.
the
Description of
the Instrument
The instrument contains a gallium arsenide infrared-emitting diode and a silicon photodetector diode spaced three centimeters apart.’-5 The light emitter and detector are built into one hand-held unit which can be placed firmly on the infant’s head (Fig. 1). This work was underwritten in part by the National Foundation-March of Dimes and The National Institutes of Health Grants #16436 and #5 P01 HD 02774. * Associate Professor, Division of Congenital Defects, Department of Pediatrics, University of Washington School of Medicine, Seattle, Wash. 98195. &dag er; Professor of Bioengineering, University ofUtah, Salt Lake City, Utah 84112. ** Center for Bioengineering, Univerity of Utah. Correspondence to Patricia W. Hayden, M.D., Department of Pediatrics, University of Washington School of Medicine, Seattle, Wash. 98195.
An oscillator
triggers
a
15-ampere pulse
to
the emitter and activates a sample-hold circuit to read peak pulse height. The pulsed light diffuses in and is absorbed by the cranial structures in direct relation to their optical density. A meter is calibrated to read the transmitted infrared intensity in optical density units per centimeter (O.D./cm). Thus, areas filled with clear fluid will absorb less light to give lower optical density read-
ings. Results Data have been obtained from 222 normal infants. Among those were 160 normal-term infants who had transilluminator readings taken from the right and left occipital, parietal, and frontal areas. A consistent relationship existed between the occipital and frontal areas, the frontal invariably measuring at least 0.1 O.D./cm less than the occipital area. The transillumination was symmetrical, the corresponding readings from the two sides of the head not differing more than 0.1 O.D./cm. The optical density readings from the frontal areas showed a range of 1.2 to 1.9 O.D./cm (Fig. 2) with a mean of 1.58 and a standard deviation of 0.13. Little correlation to birth weight
existed (r
.03). Sixty-two premature infants showed fron-
tal to
=
optical density readings ranging from 1.2 1.8 with a mean of 1.46 (Fig. 3). Again, 627
Downloaded from cpj.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 14, 2015
FiG. 1. Pulsed transilluminator: prototype
developed
there was little correlation with birth weight or head circumference but some correlation (r .61) with gestational age in that those more prematurely born transilluminated to a =
greater degree. The factor of skin pigmentation interferwith the light reading was considered and measurements of reflected light were taken from the first 50 patients in the study. The differences proved to be insignificant in all except the few (n 7) black babies available for study. These babies invariably gave optical density readings 0.1 to 0.2 greater than the mean for nonblack babies but otherwise showed the same relationships in that the frontal areas transilluminated more than the occipital and the transillumination was symmetrical from side to side. In addition to the 222 normal newborns and prematures, 59 patients were referred for transillumination because of some question of an intracranial lesion. These varied in age from newborn to five years. Examination
ing
=
at
Center for
Bioengineering, University
of
Washington.
of these patients required scanning over all areas of the skull, searching for asymmetry or unexpected areas of decreased or increased density. After data from the pulsed transilluminator examination were recorded, each infant was subjected to standard flashlight transillumination (Table 1). Seven prematurely born babies with very low optical density readings were transilluminated at weekly intervals and showed O.D. readings increasing with age. A caput succedaneum will cause a well-circumscribed area of decreased density, whereas a cephalohematoma gives optical density readings greater than 2.0. Six infants older than one week of age with optical density readings less than 1.3 subsequently were proven to have hydrocephalus by ventriculography. Four patients with localized areas of decreased density were shown by other examinations and subsequent surgery to have cysts in the area of increased transill u mi nation. With one infant it was possible by serial
628
Downloaded from cpj.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 14, 2015
FIG. 2. Frequency distribution of optical density readings obtained from 160 normal-term infants examined during the first three days of life (see text).
transilluminator examinations to follow the resolution of -a subdural hematoma complicating hydrocephalus associated with spina bifida. Discussion Even
the
most
modern, well-equipped
nursery seldom has an adequate area which can be sufficiently darkened to do a reliable clinical transillumination. The three to five minutes required for good dark adaptation
several times longer when a squirming is baby being held in a crowded closet. Nevertheless, the significance of the lesions which transillumination may reveal makes it imperative that this procedure not be omitted from the complete examination of the newborn. The instrument described in this paper can be used in ambient room light and provides quantitative data not dependent on (Continued on page 632)
seems
FIG. 3. Frequency distribution of optical density readings obtained from 62 prematurely bom infants. These babies were considered normal with respect to head growth,
neurologic development,
and flashlight transillumination (see text).
629
Downloaded from cpj.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 14, 2015
