Develop. Med. Child Neurol. 1916, 18, 160-166
Agenesis of the Corpus Callosum Revealed by Computerized Tomography A. David Rothner Paul M. Duchesneau Meredith Weinstein
lb). The EMI scanner, the first computerized tomograph, has been used to visualize primary and metastatic brain-tumors, hydrocephalus, cerebral abscesses, subdural and epidural hematomata, infarcts, hemorrhages and diffuse and focal atrophy (Baker et a/. 1974, Zelch et ul. 1974, Houser et d.1975). We report here two children in whom
Introduction Computerized tomography is a new, non-invasive, roentgenographic technique which was introduced by Ambrose and Hounsfield (Ambrose 1973, Ambrose and Hounsfield 1973, Hounsfield 1973). With this procedure the brain is shown electronically in sections (Fig. la). These resemble neuro-anatomical specimens (Fig.
Fig. la and b. Gross specimen (left) of calvarium and corresponding computerized tomography scan (right) showing cerebrospinal fluid density in lateral ventricles. Choroid plexuses are calcified. ~
~~
~
~
~
~~
~~
Correspondence to A. David Rothner, M.D., Department of Child Neurology, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44106.
160
A. DAVID ROTHNER
PAUL M. DUCHESNEAU
the condition of agenesis of the corpus callosum was found at computerized tomography. The findings were consistent with those of pneumoencephalography or angiography. The r6le of computerized tomography in the diagnosis of other intracranial congenital anomalies is also discussed.
MEREDITH WEINSTEIN
extremely small variations in tissue densities in different areas of the head. Frequently, contrast material is injected intravenously before the examination, which results in increased absorption values for highly-vascular lesions. Major difficulties encountered to date are artifacts introduced by intracranial foreign bodies and by movement. Sedation is almost always necessary for pediatric patients.
Technique The patient is placed supine o n an adjustable table, with his head inserted into a latex cap which projects into a box at the center of the machine (Fig. 2). Water fills the box and presses the latex cap firmly about the head. A carriage containing an x-ray tube is placed opposite a matching carriage on which detectors are mounted. The scanner then traverses the head, recording 240 transmission readings. The carriage then rotates one degree and the scanning is repeated in the same plane: this is repeated for each degree to 180’. The entire sequence is completed in 45 to 5 minutes. Usually four scan-sequences are accomplished. A computer calculates an absorption value for each point on the scanning plane and provides a ‘hard copy’ read-out as a visual display on an oscilloscope screen, and a print of the oscilloscope image (Fig. 3). The displayed image makes visible
Case Reports CASE
1
A five-month-old white boy was examined for right focal seizures. He had been born after a normal piegnancy, but a caesarean section had been performed after prolonged labor. Birthweight was 3.2kg and Apgar was 9 at two minutes. The neonatal course was uneventful. At four months of age, jerking of the right foot was noted and a generalized seizure lasting five minutes followed shortly afterwards. At that time, blood sugar, electrolytes. calcium, phosphorus, urine and serum amino-acid values were all normal. Skull roentgenogram, cranial transillumination, echoencephalogram, radio-isotope brain-scan, electroencephalogram and cerebrospinal fluid protein and sugar were normal. Phenobarbital (8mg/kg/24hrs) was started and he was referred to the Cleveland Clinic.
Fig. 3 Schematic diagram showing basic principles of CT brain-scanner. (Courtesy of Cleveland C h i c Quurterly.)
Fig. 2 Patient undergoing scanning.
161
DEVELOPMENTAL MEDICINE AND CHILD
On admission, physical examination revealed an alert child in no distress. There were no physical abnormalities, nor cutaneous or skeletal anomalies. Head circumferencewas 44cm, without intracranial bruit. The fontanelle was enlarged and the left frontal area was prominent. A slightly increased amount of pigment was noted in the right optic disc, and questionably decreased right-facial movement was noted. Generalized hypotonia was present, with increased deep-tendon reflexes on the left. Babinski signs were flexor. Sensory responses to pain were normal. Head control was poor and the youngster appeared to titubate excessively. No tonic neck-reflex was present and the Moro response could no longer be elicited. Laboratory data included normal values for hemoglobin, white blood-cell count, urinalysis, electrolytes, blood-urea nitrogen, creatinine, and SMA 12/60. The VDRL was negative. Titers for cytomegalovirus, toxoplasmosis and rubella were negative. An electroencephalogram revealed consistently reduced sleep activity on the left, as well as reduced waking fast activity on the left. Occasional negative sharp discharges were present at F3. The skull roentgenogram was normal. The EM1 brain-scan revealed a large cystic cavity in the posterior fossa, and a high third ventricle between widely-separated lateral ventricles (Fig. 4). An arteriogram was performed which showed changes consistent with agenesis of the corpus callosum and a posterior fossa cyst (Figs. 5 and 6). At follow-up examination four months later the
NEUROLOGY. 1976, 18
child had minimally delayed development and rare right focal seizures. CASE
2
This boy was the product of a pregnancy complicated by hypertension, but delivery was uneventful. Birthweight was 3 * 18kg. Frontal bossing was noted in the newborn peiiod and feeding was described as poor. Surgery for trigonocephaly was performed at age three months and the cosmetic result was good. At 18 months he was evaluated because of an enlarged head and developmental delay. Pneumoencephalography revealed a posterior fossa meningeal cyst and agenesis of the corpus callosum (Figs. 7 and 8). Generalized seizures had begun at 16 months. Intelligence testing at 4 t years gave an IQ of 53. On neurological re-evaluation at 11 years there had been no seizures for more than four years. He was taking phenobarbital (15mg three times daily) and was attending a school for handicapped children. Results of the general physical examination were normal and there were no skeletal or cutaneous anomalies. Head circumference was 55cm, without intracranial bruit. An increased antero-posterior diameter was noted, with bifrontal bossing. The youngster was quite awkward in his movements and there was evidence of right upper motor-neuron facial weakness. Muscle tone was generally diminished and there was right hemiatrophy. Reflexes were increased on the right, and the Babinski responses were flexor bilaterally. Cerebella1 testing revealed awkwardness but no dysmetria. Sensory examination gave largely normal results. EM1 brain-scan confirmed the earlier diagnosis of agenesis of the corpus callosum, with an associated extra-axial posterior fossa cyst (Fig. 9).
Embryology The embryology of the corpus callosum and its associated structures has been reviewed by Loeser and Alvord (1968), Carpenter and Druckemiller (1953). and Rakic and Yakovlev (1968) The corpus callosum first appears in the third month of intrauterine development in an area dorsal to the laminate terminalis. It gradually increases in size, first in a cephalad direction, then curving and extending in a caudad direction, forming first the rostrum and then the genu and body. It is inter-
Fig. 4. CT-scan showing enlarged third ventricle
between the lateral ventricles and large cystic cavity in posterior fossa.
162
A. DAVID ROTHNER
PAUL M. DUCHESNEAU
MEREDITH WEINSTEIN
Fig. 5 (left).Right common carotid arteriogram (Case l), showing anterior cerebral artery crossing region normally occupied by rostrum and genu of corpus callosum. Middle cerebral artery branches do not make their normal turns in the Sylvian fissure. Fig. 6 (right). Left vertebral injection shows avascular area in posterior fossa.
Fig. 7 ( l e f ) . Pneumoencephalogram (Case 2) shows wide separation, angular dorsal margins (bat-wing appearance) and concave medial borders of lateral ventricles, with dorsal extension and dilation of third ventricle. Fig. 8 (right). Lateral projection shows extra-axial posterior fossa cyst.
occurs. The development of the sulci and gyri on the medial aspects of the hemispheres depends on callosal formation, hence agenesis of the corpus callosum is frequently associated with midline malformations (e.g. absent septum pellucidurn). The agenesis may also be associated with more generalized malformations such as extra-axial cysts, polygyria, agyria,
posed between the medial aspects of both cerebral hemispheres. Development is complete by the fifth month of gestation. The corpus callosum is critical in guiding migrating neurons and glial cells to their ultimate cortical destination (Menkes 1974). Whether agenesis of the corpus callosum is complete or partial depends on the time at which a teratogenic insult 163
DEVELOPMENTAL MEDICINE A N D CHILD NEUROLOGY.
1976, 18
A number of cases have been reported in which agenesis of the corpus callosum was noted incidentally at autopsy, no neurological deficits having been noted prior to death (Grogono 1968). Experimental data from both animals and humans in whom the corpus callosum was transected to control seizures suggest that a result may be a subtle difficulty in transferring information from one hemisphere to another. Several reviews of these behavioral investigations have been published (Gazzaniga and Sperry 1967, Loeser and Alvord 1968, Ettlinger et a/. 1972). Fig. 9. CT-scan (Case 2) shows dilated third ventricle, large extra-axial posterior fossa cyst, and superiorly displaced third ventricle which separates lateral ventricles
pachygyria and grey-matter heterotopias. Other anomalies may be present, especially those of the midline such as cranium bifidum and cleft palate (Carpenter and Druckemiller 1953, Loeser and Alvord 1968, Menkes 1974, Rakic and Yakovlev 1968). Clinical Aspects Although the occurrence of agenesis of the corpus callosum is usually sporadic, an x-linked variety has been described (Menkes 1964). The clinical correlates of this condition are widely disparate and in most instances depend on the degree and type of associated malformations (Carpenter and Druckemiller 1953, Menkes 1974). No significant sexual distribution has been noted and there are no apparent predisposing causes. Symptoms become apparent shortly after birth or before two years in more than half the cases, and in most cases before the age of 20 years. Seizures, an enlarging head, mental retardation, and focal neurological deficits such as hemiparesis are among the most frequently-associated clinical symptoms (Carpenter and Druckemiller 1953).
Roentgenographic Findings Eighteen years after the introduction of pneumoencephalography by Dandy in 1918, Davidoff and Dyke (1934) made the first in vivo diagnosis of agenesis of the corpus callosum. They established the following pneumoencephalographic criteria for the diagnosis: (1) wide separation of the lateral ventricles; (2) angular dorsal margins of the lateral ventricles (bat-wing appearance); (3) concave medial borders of lateral \Jentricles; (4) dilatation of the occipital horns of the late ra 1 ventricles ; (5) enlargement of the intraventricular foramina ; (6) dorsal extension and dilatation of the third ventricle; (7) radial arrangement of sulci on medial surface of hemisphere (this finding is difficult to appreciate with pneumoencephalography). The following angiographic features have been found in agenesis of the corpus callosum (Sheldon and Peyman 1953): ( I ) The anterior cerebral arteries run directly superiorly. The arteries cross the region normally occupied by the rostrum and genu of the corpus callosum. (2) The pericallosal arteries either rapidly divide into several branches arranged in a 164
A. DAVID ROTHNER
PAUL M. DUCHESNEAU
radial fashion, or make a sharp turn posteriorly and meander posteriorly. The meandering branches frequently lie immediately above the roof of the third ventricle. The pericallosal arteries are about 2cm superior to the roof of the third ventricle. (3) Rarely, the middle cerebral branches have an increased slope. The internal cerebral vein and the great vein of Galen are frequently displaced superiorly and posteriorly. The distance is reduced between the internal cerebral vein and both the inferior sagittal sinus and the pericatlosal arterj. (4) The internal cerebral veins are displaced laterally. Computerized tomography findings in agenesis of the corpus callosum are identical to those on pneumoencephalography, with the exception that the batwing appearance is difficult to appreciate (see Figs. 4 and 9). Discussion Computerized tomography is a safe,
MEREDITH WEINSTEIN
precise and non-invasive neuroradiological technique for diagnosis of agenesis of the corpus callosum and is without the attendant risks of pneumoencephalography and arteriography. The incidental findings of a posterior fossa meningeal cyst in both patients reported here, as well as the presence of hydrocephalus, focal atrophy and porencephalic cysts in other patients, confirm the belief that this method is helpful in clarifying numerous other anomalies of the central nervous system. The technique is of considerable help in the non-invasive evaluation of children with mental retardation, seizures, and suspected congenital anomalies of the central nervous system.
AUTHORS’ APPOINTMENTS
A. David Rothner, M.D., Head, Section of Pediatric Neurology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio 44106. Paul M. Duchesneau, M.D.; Meridith Weinstein, M.D.; Cleveland Clinic Foundation.
SUM MARY
Computerized tomography is a new, safe, non-invasive method of diagnosing intracranial disorders. It has been used in the detection of intracranial tumors, hydrocephalus, hemorrhages, atrophy, abscesses and subdural hematomata. Two cases of agenesis of the corpus callosum are presented, in which the diagnosis was made or confirmed by computerized tomography. The embryology, clinical course and radiological aspects of the disorder are reviewed. RESUMG
Agknhsie du corps ca1leu.u diagtiostiquh par tomographie programmhe La toniographie programmke est une mkthode nouvelle, silre, anodine, de diagnostic des troubles intra-criniens. Elle a etk utilisee dans la detection des tumeurs intra-criniennes, de I’hydroctphalie, des hkmorragies, de l’atrophie, des abcts et des himatomes sous-duraux. Deux cas d’agkndsie du corps calleux diagnostiquks par tomographie programmke sont prisentis. L’embryologie, l’tvolution clinique et les aspects radiologiques du trouble sont k t udiks. ZUSAM MENFASSUNG
Agetiesie des Corpus callosum, diagriostiziert mit koniputerisierter Tomographie Die komputerisierte Tomographie ist eine neue, sichere und nicht invasive Methode zur Diagnostik intrakranieller Sttirungen. Sie wurde angewandt zur Feststellung intrakranieller Tumoren, des Hydrozephalus, von Hiimorrhsgien, Atrophie, Abszessen und subduralen Hamatomen. 165
DEVELOPMENTAL MEDICINE AND CHILD
NEUROLOGY. 1976, 18
Es werden zwei Falle von Agenesie des Corpus callosum, diagnostiziert mit komputerisierter Tomographie, vorgestellt. Die Ernbryologie, der klinische Verlauf und die radiologischen Aspekte dieser Storung werden ausfiihrlich behandelt. RES U MEN
Agenesia del cuerpo calloso diagnosticado por medio de la tomografia computadorizada La tomografia computadorizada es un mCtodo nuevo, inocuo y no invasivo para el diagnostic0 de alteraciones endocraneanas. Se ha usado en la deteccion de tumores intracraneales, hidrocefalia, hemorragias, atrofia, abcesos y hematomas subdurales. Se presentan dos casos de agenesia del cuerpo calloso diagnosticados por medio de la tomografia computadorizada. Se revisan la embriologia, el curso clinico y 10s aspectos radiologicos de la enfermedad. REFERENCES Ambrose, J. (1973) ‘Computerized transverse axial scanning (tomography): Part 2, Clinical application.’ British Journal of Radiology, 46, 1023. - Hounsfield, G. N. (1973) ‘Computerized transverse axial tomography.’ British Journal of Radiology, 46, 148.
Baker, H. L., Campbell, J. K., Houser, 0. W., Reese, D. F., Sheedy, P. F., Holman, C. B. (1974) ‘Computer assisted tomography of the head: an early evaluation.’ Mayo Clinic Proceedings, 49, 17. Carpenter, M. B., Druckemiller, W. H. (1953) ‘Agenesis of the corpus callosum diagnosed during life.’ Archives of Neurology and Psychiatry, 69, 305. Davidoff, L. M., Dyke, C. G. (1934) ‘Agenesis of the corpus callosum; its diagnosis by encephalography.’ American Journal of Roentgenology, 32, I . Ettlinger, G., Blakemore, C. B., Milner, A. D., Wilson, J. (1972) ‘Agenesis of the corpus callosum: a behavioral investigation.’ Brain, 95, 327. Gazzaniga, M. S., Sperry, R. W. (1967) ‘Language after section of the cerebral commisures.’ Brain, 90,131. Gronogo, J. L. (1968) ‘Children with agenesis of the corpus callosum.’ Developmental Medicine and Child Neurology, 10,6 13. Hounsfield, G. N. (1973) ‘Computerized transverse axial scanning (tomography): Part 1, Description of system.’ British Journal of Radiology, 46, 1016. Houser, 0. W., Smith, J. B., Gomez, M. R., Baker, H. L. (1975) ‘Evaluation of intracranial disorders in children by computerized transaxial tomography: a preliminary report.’ Neurology, 25, 607. Loeser, J. D., Alvord, E. C., Jr. (1968) ‘Agenesis of the corpus callosum.’ Brain, 91, 553. Menkes, J. H., Phillipart, M., Clark, D. B. (1964) ‘Hereditary partial agenesis of the corpus callosum.’ Archives of Neurology, 11, 198. - (1974) Textbook of Child Neurology. Philadelphia: Lea & Febiger. Rakic. P.. Yakovlev. P. (19681 ‘Develooment of the corDus callosum and cavum seoti in man.’ Journal of Comparative Neurology, 132, 45. Sheldon, P., Peyman, A. (1953) ‘The radiological appearances of agenesis of the corpus callosum.’ Journal of Neurology, Neurosurgery and Psychiatry, 16, 117. Zelch, J. V., Duchesneau, P. M., Meaney, T. F., Lalli, A. F., Alfidi, R. J., Zelch, M. G. (1974) ‘The EM1 scanner and its application to clinical diagnosis.’ Cleveland Clinic Quarterly, 41, 79.
166
Agenesis of the Corpus Callosum Revealed by Computerized Tomography A. David Rothner Paul M. Duchesneau Meredith Weinstein
lb). The EMI scanner, the first computerized tomograph, has been used to visualize primary and metastatic brain-tumors, hydrocephalus, cerebral abscesses, subdural and epidural hematomata, infarcts, hemorrhages and diffuse and focal atrophy (Baker et a/. 1974, Zelch et ul. 1974, Houser et d.1975). We report here two children in whom
Introduction Computerized tomography is a new, non-invasive, roentgenographic technique which was introduced by Ambrose and Hounsfield (Ambrose 1973, Ambrose and Hounsfield 1973, Hounsfield 1973). With this procedure the brain is shown electronically in sections (Fig. la). These resemble neuro-anatomical specimens (Fig.
Fig. la and b. Gross specimen (left) of calvarium and corresponding computerized tomography scan (right) showing cerebrospinal fluid density in lateral ventricles. Choroid plexuses are calcified. ~
~~
~
~
~
~~
~~
Correspondence to A. David Rothner, M.D., Department of Child Neurology, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44106.
160
A. DAVID ROTHNER
PAUL M. DUCHESNEAU
the condition of agenesis of the corpus callosum was found at computerized tomography. The findings were consistent with those of pneumoencephalography or angiography. The r6le of computerized tomography in the diagnosis of other intracranial congenital anomalies is also discussed.
MEREDITH WEINSTEIN
extremely small variations in tissue densities in different areas of the head. Frequently, contrast material is injected intravenously before the examination, which results in increased absorption values for highly-vascular lesions. Major difficulties encountered to date are artifacts introduced by intracranial foreign bodies and by movement. Sedation is almost always necessary for pediatric patients.
Technique The patient is placed supine o n an adjustable table, with his head inserted into a latex cap which projects into a box at the center of the machine (Fig. 2). Water fills the box and presses the latex cap firmly about the head. A carriage containing an x-ray tube is placed opposite a matching carriage on which detectors are mounted. The scanner then traverses the head, recording 240 transmission readings. The carriage then rotates one degree and the scanning is repeated in the same plane: this is repeated for each degree to 180’. The entire sequence is completed in 45 to 5 minutes. Usually four scan-sequences are accomplished. A computer calculates an absorption value for each point on the scanning plane and provides a ‘hard copy’ read-out as a visual display on an oscilloscope screen, and a print of the oscilloscope image (Fig. 3). The displayed image makes visible
Case Reports CASE
1
A five-month-old white boy was examined for right focal seizures. He had been born after a normal piegnancy, but a caesarean section had been performed after prolonged labor. Birthweight was 3.2kg and Apgar was 9 at two minutes. The neonatal course was uneventful. At four months of age, jerking of the right foot was noted and a generalized seizure lasting five minutes followed shortly afterwards. At that time, blood sugar, electrolytes. calcium, phosphorus, urine and serum amino-acid values were all normal. Skull roentgenogram, cranial transillumination, echoencephalogram, radio-isotope brain-scan, electroencephalogram and cerebrospinal fluid protein and sugar were normal. Phenobarbital (8mg/kg/24hrs) was started and he was referred to the Cleveland Clinic.
Fig. 3 Schematic diagram showing basic principles of CT brain-scanner. (Courtesy of Cleveland C h i c Quurterly.)
Fig. 2 Patient undergoing scanning.
161
DEVELOPMENTAL MEDICINE AND CHILD
On admission, physical examination revealed an alert child in no distress. There were no physical abnormalities, nor cutaneous or skeletal anomalies. Head circumferencewas 44cm, without intracranial bruit. The fontanelle was enlarged and the left frontal area was prominent. A slightly increased amount of pigment was noted in the right optic disc, and questionably decreased right-facial movement was noted. Generalized hypotonia was present, with increased deep-tendon reflexes on the left. Babinski signs were flexor. Sensory responses to pain were normal. Head control was poor and the youngster appeared to titubate excessively. No tonic neck-reflex was present and the Moro response could no longer be elicited. Laboratory data included normal values for hemoglobin, white blood-cell count, urinalysis, electrolytes, blood-urea nitrogen, creatinine, and SMA 12/60. The VDRL was negative. Titers for cytomegalovirus, toxoplasmosis and rubella were negative. An electroencephalogram revealed consistently reduced sleep activity on the left, as well as reduced waking fast activity on the left. Occasional negative sharp discharges were present at F3. The skull roentgenogram was normal. The EM1 brain-scan revealed a large cystic cavity in the posterior fossa, and a high third ventricle between widely-separated lateral ventricles (Fig. 4). An arteriogram was performed which showed changes consistent with agenesis of the corpus callosum and a posterior fossa cyst (Figs. 5 and 6). At follow-up examination four months later the
NEUROLOGY. 1976, 18
child had minimally delayed development and rare right focal seizures. CASE
2
This boy was the product of a pregnancy complicated by hypertension, but delivery was uneventful. Birthweight was 3 * 18kg. Frontal bossing was noted in the newborn peiiod and feeding was described as poor. Surgery for trigonocephaly was performed at age three months and the cosmetic result was good. At 18 months he was evaluated because of an enlarged head and developmental delay. Pneumoencephalography revealed a posterior fossa meningeal cyst and agenesis of the corpus callosum (Figs. 7 and 8). Generalized seizures had begun at 16 months. Intelligence testing at 4 t years gave an IQ of 53. On neurological re-evaluation at 11 years there had been no seizures for more than four years. He was taking phenobarbital (15mg three times daily) and was attending a school for handicapped children. Results of the general physical examination were normal and there were no skeletal or cutaneous anomalies. Head circumference was 55cm, without intracranial bruit. An increased antero-posterior diameter was noted, with bifrontal bossing. The youngster was quite awkward in his movements and there was evidence of right upper motor-neuron facial weakness. Muscle tone was generally diminished and there was right hemiatrophy. Reflexes were increased on the right, and the Babinski responses were flexor bilaterally. Cerebella1 testing revealed awkwardness but no dysmetria. Sensory examination gave largely normal results. EM1 brain-scan confirmed the earlier diagnosis of agenesis of the corpus callosum, with an associated extra-axial posterior fossa cyst (Fig. 9).
Embryology The embryology of the corpus callosum and its associated structures has been reviewed by Loeser and Alvord (1968), Carpenter and Druckemiller (1953). and Rakic and Yakovlev (1968) The corpus callosum first appears in the third month of intrauterine development in an area dorsal to the laminate terminalis. It gradually increases in size, first in a cephalad direction, then curving and extending in a caudad direction, forming first the rostrum and then the genu and body. It is inter-
Fig. 4. CT-scan showing enlarged third ventricle
between the lateral ventricles and large cystic cavity in posterior fossa.
162
A. DAVID ROTHNER
PAUL M. DUCHESNEAU
MEREDITH WEINSTEIN
Fig. 5 (left).Right common carotid arteriogram (Case l), showing anterior cerebral artery crossing region normally occupied by rostrum and genu of corpus callosum. Middle cerebral artery branches do not make their normal turns in the Sylvian fissure. Fig. 6 (right). Left vertebral injection shows avascular area in posterior fossa.
Fig. 7 ( l e f ) . Pneumoencephalogram (Case 2) shows wide separation, angular dorsal margins (bat-wing appearance) and concave medial borders of lateral ventricles, with dorsal extension and dilation of third ventricle. Fig. 8 (right). Lateral projection shows extra-axial posterior fossa cyst.
occurs. The development of the sulci and gyri on the medial aspects of the hemispheres depends on callosal formation, hence agenesis of the corpus callosum is frequently associated with midline malformations (e.g. absent septum pellucidurn). The agenesis may also be associated with more generalized malformations such as extra-axial cysts, polygyria, agyria,
posed between the medial aspects of both cerebral hemispheres. Development is complete by the fifth month of gestation. The corpus callosum is critical in guiding migrating neurons and glial cells to their ultimate cortical destination (Menkes 1974). Whether agenesis of the corpus callosum is complete or partial depends on the time at which a teratogenic insult 163
DEVELOPMENTAL MEDICINE A N D CHILD NEUROLOGY.
1976, 18
A number of cases have been reported in which agenesis of the corpus callosum was noted incidentally at autopsy, no neurological deficits having been noted prior to death (Grogono 1968). Experimental data from both animals and humans in whom the corpus callosum was transected to control seizures suggest that a result may be a subtle difficulty in transferring information from one hemisphere to another. Several reviews of these behavioral investigations have been published (Gazzaniga and Sperry 1967, Loeser and Alvord 1968, Ettlinger et a/. 1972). Fig. 9. CT-scan (Case 2) shows dilated third ventricle, large extra-axial posterior fossa cyst, and superiorly displaced third ventricle which separates lateral ventricles
pachygyria and grey-matter heterotopias. Other anomalies may be present, especially those of the midline such as cranium bifidum and cleft palate (Carpenter and Druckemiller 1953, Loeser and Alvord 1968, Menkes 1974, Rakic and Yakovlev 1968). Clinical Aspects Although the occurrence of agenesis of the corpus callosum is usually sporadic, an x-linked variety has been described (Menkes 1964). The clinical correlates of this condition are widely disparate and in most instances depend on the degree and type of associated malformations (Carpenter and Druckemiller 1953, Menkes 1974). No significant sexual distribution has been noted and there are no apparent predisposing causes. Symptoms become apparent shortly after birth or before two years in more than half the cases, and in most cases before the age of 20 years. Seizures, an enlarging head, mental retardation, and focal neurological deficits such as hemiparesis are among the most frequently-associated clinical symptoms (Carpenter and Druckemiller 1953).
Roentgenographic Findings Eighteen years after the introduction of pneumoencephalography by Dandy in 1918, Davidoff and Dyke (1934) made the first in vivo diagnosis of agenesis of the corpus callosum. They established the following pneumoencephalographic criteria for the diagnosis: (1) wide separation of the lateral ventricles; (2) angular dorsal margins of the lateral ventricles (bat-wing appearance); (3) concave medial borders of lateral \Jentricles; (4) dilatation of the occipital horns of the late ra 1 ventricles ; (5) enlargement of the intraventricular foramina ; (6) dorsal extension and dilatation of the third ventricle; (7) radial arrangement of sulci on medial surface of hemisphere (this finding is difficult to appreciate with pneumoencephalography). The following angiographic features have been found in agenesis of the corpus callosum (Sheldon and Peyman 1953): ( I ) The anterior cerebral arteries run directly superiorly. The arteries cross the region normally occupied by the rostrum and genu of the corpus callosum. (2) The pericallosal arteries either rapidly divide into several branches arranged in a 164
A. DAVID ROTHNER
PAUL M. DUCHESNEAU
radial fashion, or make a sharp turn posteriorly and meander posteriorly. The meandering branches frequently lie immediately above the roof of the third ventricle. The pericallosal arteries are about 2cm superior to the roof of the third ventricle. (3) Rarely, the middle cerebral branches have an increased slope. The internal cerebral vein and the great vein of Galen are frequently displaced superiorly and posteriorly. The distance is reduced between the internal cerebral vein and both the inferior sagittal sinus and the pericatlosal arterj. (4) The internal cerebral veins are displaced laterally. Computerized tomography findings in agenesis of the corpus callosum are identical to those on pneumoencephalography, with the exception that the batwing appearance is difficult to appreciate (see Figs. 4 and 9). Discussion Computerized tomography is a safe,
MEREDITH WEINSTEIN
precise and non-invasive neuroradiological technique for diagnosis of agenesis of the corpus callosum and is without the attendant risks of pneumoencephalography and arteriography. The incidental findings of a posterior fossa meningeal cyst in both patients reported here, as well as the presence of hydrocephalus, focal atrophy and porencephalic cysts in other patients, confirm the belief that this method is helpful in clarifying numerous other anomalies of the central nervous system. The technique is of considerable help in the non-invasive evaluation of children with mental retardation, seizures, and suspected congenital anomalies of the central nervous system.
AUTHORS’ APPOINTMENTS
A. David Rothner, M.D., Head, Section of Pediatric Neurology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio 44106. Paul M. Duchesneau, M.D.; Meridith Weinstein, M.D.; Cleveland Clinic Foundation.
SUM MARY
Computerized tomography is a new, safe, non-invasive method of diagnosing intracranial disorders. It has been used in the detection of intracranial tumors, hydrocephalus, hemorrhages, atrophy, abscesses and subdural hematomata. Two cases of agenesis of the corpus callosum are presented, in which the diagnosis was made or confirmed by computerized tomography. The embryology, clinical course and radiological aspects of the disorder are reviewed. RESUMG
Agknhsie du corps ca1leu.u diagtiostiquh par tomographie programmhe La toniographie programmke est une mkthode nouvelle, silre, anodine, de diagnostic des troubles intra-criniens. Elle a etk utilisee dans la detection des tumeurs intra-criniennes, de I’hydroctphalie, des hkmorragies, de l’atrophie, des abcts et des himatomes sous-duraux. Deux cas d’agkndsie du corps calleux diagnostiquks par tomographie programmke sont prisentis. L’embryologie, l’tvolution clinique et les aspects radiologiques du trouble sont k t udiks. ZUSAM MENFASSUNG
Agetiesie des Corpus callosum, diagriostiziert mit koniputerisierter Tomographie Die komputerisierte Tomographie ist eine neue, sichere und nicht invasive Methode zur Diagnostik intrakranieller Sttirungen. Sie wurde angewandt zur Feststellung intrakranieller Tumoren, des Hydrozephalus, von Hiimorrhsgien, Atrophie, Abszessen und subduralen Hamatomen. 165
DEVELOPMENTAL MEDICINE AND CHILD
NEUROLOGY. 1976, 18
Es werden zwei Falle von Agenesie des Corpus callosum, diagnostiziert mit komputerisierter Tomographie, vorgestellt. Die Ernbryologie, der klinische Verlauf und die radiologischen Aspekte dieser Storung werden ausfiihrlich behandelt. RES U MEN
Agenesia del cuerpo calloso diagnosticado por medio de la tomografia computadorizada La tomografia computadorizada es un mCtodo nuevo, inocuo y no invasivo para el diagnostic0 de alteraciones endocraneanas. Se ha usado en la deteccion de tumores intracraneales, hidrocefalia, hemorragias, atrofia, abcesos y hematomas subdurales. Se presentan dos casos de agenesia del cuerpo calloso diagnosticados por medio de la tomografia computadorizada. Se revisan la embriologia, el curso clinico y 10s aspectos radiologicos de la enfermedad. REFERENCES Ambrose, J. (1973) ‘Computerized transverse axial scanning (tomography): Part 2, Clinical application.’ British Journal of Radiology, 46, 1023. - Hounsfield, G. N. (1973) ‘Computerized transverse axial tomography.’ British Journal of Radiology, 46, 148.
Baker, H. L., Campbell, J. K., Houser, 0. W., Reese, D. F., Sheedy, P. F., Holman, C. B. (1974) ‘Computer assisted tomography of the head: an early evaluation.’ Mayo Clinic Proceedings, 49, 17. Carpenter, M. B., Druckemiller, W. H. (1953) ‘Agenesis of the corpus callosum diagnosed during life.’ Archives of Neurology and Psychiatry, 69, 305. Davidoff, L. M., Dyke, C. G. (1934) ‘Agenesis of the corpus callosum; its diagnosis by encephalography.’ American Journal of Roentgenology, 32, I . Ettlinger, G., Blakemore, C. B., Milner, A. D., Wilson, J. (1972) ‘Agenesis of the corpus callosum: a behavioral investigation.’ Brain, 95, 327. Gazzaniga, M. S., Sperry, R. W. (1967) ‘Language after section of the cerebral commisures.’ Brain, 90,131. Gronogo, J. L. (1968) ‘Children with agenesis of the corpus callosum.’ Developmental Medicine and Child Neurology, 10,6 13. Hounsfield, G. N. (1973) ‘Computerized transverse axial scanning (tomography): Part 1, Description of system.’ British Journal of Radiology, 46, 1016. Houser, 0. W., Smith, J. B., Gomez, M. R., Baker, H. L. (1975) ‘Evaluation of intracranial disorders in children by computerized transaxial tomography: a preliminary report.’ Neurology, 25, 607. Loeser, J. D., Alvord, E. C., Jr. (1968) ‘Agenesis of the corpus callosum.’ Brain, 91, 553. Menkes, J. H., Phillipart, M., Clark, D. B. (1964) ‘Hereditary partial agenesis of the corpus callosum.’ Archives of Neurology, 11, 198. - (1974) Textbook of Child Neurology. Philadelphia: Lea & Febiger. Rakic. P.. Yakovlev. P. (19681 ‘Develooment of the corDus callosum and cavum seoti in man.’ Journal of Comparative Neurology, 132, 45. Sheldon, P., Peyman, A. (1953) ‘The radiological appearances of agenesis of the corpus callosum.’ Journal of Neurology, Neurosurgery and Psychiatry, 16, 117. Zelch, J. V., Duchesneau, P. M., Meaney, T. F., Lalli, A. F., Alfidi, R. J., Zelch, M. G. (1974) ‘The EM1 scanner and its application to clinical diagnosis.’ Cleveland Clinic Quarterly, 41, 79.
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