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Intracranial changes with unilateral coronal synostosis
Surg Neurol 1984;22:249-52
249
Intracranial Changes with Unilateral Coronal Synostosis Nobuhiko Aoki, M.D. Department of Neurosurgery, Fuchu Metropolitan Hospital, Tokyo, Japan
Aoki N. Intracranial changes with unilateral coronal synostosis. Surg Neurol 1984;22:249-52.
Case Report
Intracranial changes in two patients with unilateral coronal synostosis were evaluated by computed tomography (CT). Preoperative CT scans showed local compression of the brain by the flattened frontal bone with definite shift of the midline structures, suggesting that unilateral coronal synostosis may be harmful to the growing brain in infants. Postoperative restoration of the intracranial changes led me to draw the conclusion that unilateral coronal synostosis should be treated as early as possible not only for cosmetic reasoJas but also for the prevention of parenchymal damage.
A 18-month-old boy was presented with complaints of craniofacial deformities since birth. The pregnancy and delivery had been normal. On admission, neurological examination showed normal psychomotor development, but flattening o f the right frontal region, right exophthalmos, right temporal bulging, and asymmetry of the maxilla and mandible (Figure 1A). X-ray films of the skull revealed absence o f the right coronal suture, elevation of the right sphenoidal ridge, and bulging of the right temporal bone. Computed tomography scans (Figure 2) showed deviation of the right lateral and third ventricles, bowing of the interhemispheric fissure to the left side, and flattening of the frontal bone, suggesting compression of the frontal lobe. In addition, moderate enlargement of the lateral and third ventricles as well as the subarachnoid spaces could be seen, although that immediately beneath the flattened frontal bone was spared. Lateral canthal advancement was carried out to the unilateral coronal synostosis on the left side on N o v e m ber 24, 1981. The photograph (Figure 1B) taken 11 months after the operation shows a disappearance of the craniofacial asymmetry, achieving excellent cosmetic results. His developmental milestones remained normal thereafter. Computed tomography scans (Figure 3) performed 13 months after the operation demonstrated a remarkable reduction of the displacement of the right lateral and third ventricles as well as the interhemispheric fissure, and revealed an elevation of the free bone flap in the frontal region, together with a widening of subarachnoid spaces just beneath it.
KEY WORDS: Craniosynostosis; Unilateral coronal synostosis; Computed tomography; Brain damage, compression
T h e r e are two reasons for carrying out operative treatment of craniosynostosis: first, a cosmetic deformity can be alleviated and, second, impairment of the growing brain can be minimized. It has been questioned whether synostosis of one suture alone can distort the brain sufficiently to produce an abnormality of the central nervous system [4,5]. The above-mentioned concept was, however, the opinion before the advent of the CT scan. T h e r e have been only a few reports assessing the intracranial changes in unilateral coronal synostosis using a CT scan [1]. The author has operated on two patients with unilateral coronal synostosis by means of lateral canthal advancement [2] since the introduction of CT scan. This paper presents the preoperative and postoperative intracranial changes in tihese two cases. In addition, the theoretical basis for th,e treatment of unilateral coronal synostosis is discussed.
Address reprint requests to: Dr. Nobuhiko Aoki, Department of Neurosurgery, Fuchu Metropolitan Hospital, 2-9-2- Musashidai, Fuchu-Shi, Tokyo 183, Japan.
© 1984 by Elsevier Science Publishing Co., Inc.
Case 1
Case 2 A 6-year-old boy was referred for evaluation of craniofacial asymmetry, which had been detected at birth. His mother's pregnancy had been unremarkable as was the delivery. T h e r e was no significant family history. Neurologically, he was assessed to be normal. His craniofacial appearance (Figure 4) was typical of unilateral coronal synostosis, including flattening o f the right fron0090-3019/84/$3.00
250
Surg Neurol 1984;22:249-52
Aoki
A
Figure 1. (A) Preoperative (November 1981) and (B) postoperative (September 1982) photographs in case 1. Prominent asymmetry~ including a flattening on the frontal region, and an exophthalmos on the right side (A), was restored to almost normal (B).
Figure 2 (A-D). Preoperative C T scans in case I showed deviation of the right lateral and third ventricles, bowing of the interhemispheric fissure to the left side, and flattening of the frontal bone. Note enlargement of the ventricles and subarachnoid spaces, sparing that immediately beneath the flattened frontal bone.
tal region, right exophthalmos, and bulging of the temporal region. Plain x-ray films of the skull showed absence of the right coronal suture. Computed tomography scans (Figure 5) revealed displacement of the right lateral and third ventricles to the left side, bowing of the interhemispheric fissure, and flattening of the right frontal bone. They also disclosed moderate enlargement of the ventricles and subarachnoid spaces, without involving the subarachnoid space just beneath the depressed
Figure 3. Postoperative C T scan in case 1 (after 13 months) demonstrated a reduction of the distortion. Note an elevation of the free boneflap, together with a widening of subarachnoid spaces just under it.
Unilateral Coronal Synostosis
A
frontal bone. H e underwent a lateral canthal advancement for the right unilateral coronal synostosis on September 8, 1981. Computed tomography scans performed 3 months after the operation (Figure 6) showed a reduction of the displacement of the right lateral and third ventricles as wel]i as the interhemispheric fissure, an elevation of the free bone flap in the right frontal region, with a widening o f the subarachnoid spaces immediately beneath it. The photograph taken 20 months after the operation (Figure 4B) revealed complete restoration o f the craniofacial symmetry. His psychomotor developmental milestones remained normal.
Surg Neurol 1984;22:249-52
251
B
Figure 4. Preoperative (A) and postoperative (B) photographs in case 2, showing a symmetrical restoration by lateral cathal advancement. Discussion According to Matson, it is highly questionable whether or not synostosis o f one suture alone can distort the brain sufficiently to produce any general or focal abnormality of the central nervous system; therefore, its treatment is performed exclusively for cosmetic reasons [4]. Similarly, Milhorat states that in patients with premature closure of one cranial suture, the considerations are mainly cosmetic, and operations for stenosis of a single coronal suture performed 9 months after birth
Figure 5. Preoperative C T Jcans in case 2 showed a displacement of the right lateral and third ventricles as well as the interhemispheric fissure to the left side. In addition, th 0 revealed a moderate enlargement of the ventricles and subarachnoid spaces, without involving the subarachnoid space immediately beneath the depressed frontal bone.
Figure 6. Postoperative C T scans in case 2 demonstrated a reduction of the parenchymal deformities, and a widening of the subarachnoid space just under the elevated bone flap.
252
Surg Neurol 1984;22:249-52
usually do not restore normal cranial configuration [5]. Thus, it has been regarded that synostosis of one suture alone may not produce brain damage, but this opinion preceded the advent o f CT scan. Recently, it became apparent that when a coronal suture fuses, the frontosphenoidal and frontoethomoidal sutures close as well [2,8]. Based on their combination, unilateral coronal synostosis is not a synostosis of a single suture, but of multiple sutures. From these reasons, Hoffman and Mohr proposed lateral canthal advancement o f the supraorbital margin [2] and Marsh and Schwartz evolved a further extended procedure [3]. M o r e recently, Carmel et al evaluated intracranial changes in nine cases with unilateral coronal synostosis by CT scan [1]. T h e y showed the probability of some degree of parenchymal damage by local compression due to the foreshortened frontal base and flattened frontal calvarium. C o m p u t e d tomographic appearances in both o f our patients presented here are almost the same as those o f Carmel et al: local pressure on the frontal lobe and a definite shift o f the midline structures. These gross deformities of the brain are considered to be produced by compression of the frontal bone because they can restore a normal configuration by treatment with lateral canthal advancement. In postoperative CT scans, there appears a prominent cerebrospinal fluid space at the site of a formerly fused coronal suture. Carmel et al speculated that this is caused either by expansion of the decompressed cerebrospinal fluid pathways into an open bony defect or by local brain atrophy [1]. Similar computed tomographic findings were obtained in both patients in this paper. It seems unlikely, however, that the dilatation of the spaces under the formerly fused suture is produced by local atrophy, because it was associated with a definite elevation of the free bone flap in both patients. It is reasonable to consider that the dilatation is caused by the
Aoki
restoration of cerebrospinal fluid circulation, which is the result of decompression at the fused site by lateral canthal advancement. T h e elevation o f the free bone flap and restoration of shift of midline structure imply that unilateral coronal synostosis may, at least morphologically, be significantly harmful to the developing brain in infants. In addition, these c o m p u t e d tomographic findings may support the concept insisted upon by M o h r et al [6] and Renier et al [7] that intracranial hypertension can develop in cases with unilateral coronal synostosis. It is not definite whether unilateral coronal synostosis can actually produce brain damage. Based on computed tomographic appearances seen in this report, however, it is concluded that patients with unilateral coronal synostosis should be treated as early as possible not only for cosmetic reasons but also to prevent any possible harm to the growing and developing brain. References 1. Carmel pw, Luken MG III, Ascherl GF, Jr. Craniosynostosis: Computed tomographic valuation of skull base and calvarial deformities and associated intracranial changes. Neurosurgery 1981;9:366-72. 2. Hoffman HJ, Mohr G. Lateral canthal advancement of the supraorbital margin: a new corrective technique in the treatment of coronal synostosis.J Neurosurg 1976;45:376-81. 3. Marsh JL, Schwartz HG. The surgical correction of coronal and metopic craniosynostosis.J Neurosurg 1983;59:245-51. 4. Matson DD. Neurosurgery of infancy and childhood. Ed 2. Springfield, Ill: CC Thomas, 1969:122-67. 5. Milhorat TH. Pediatric neurosurgery. Philadelphia: FA Davis, 1978:171-90. 6. Mohr G, Hoffman HJ, Munro IR, et al. Surgical management of unilateral and bilateral coronal synostosis: 21 years of experience. Neurosurgery 1978;2:83-92. 7. Renier D, Sante-Rose C, Marchac D, Hirsch J. Intracranial pressure in craniostenosis. J Neurosurg 1982;57:370-7. 8. Seeger JF, Gabrielsen TO. Premature closure of the frontosphenoidal suture in synostosis of the coronal suture. Radiology 1971;101:631-5.
249
Intracranial Changes with Unilateral Coronal Synostosis Nobuhiko Aoki, M.D. Department of Neurosurgery, Fuchu Metropolitan Hospital, Tokyo, Japan
Aoki N. Intracranial changes with unilateral coronal synostosis. Surg Neurol 1984;22:249-52.
Case Report
Intracranial changes in two patients with unilateral coronal synostosis were evaluated by computed tomography (CT). Preoperative CT scans showed local compression of the brain by the flattened frontal bone with definite shift of the midline structures, suggesting that unilateral coronal synostosis may be harmful to the growing brain in infants. Postoperative restoration of the intracranial changes led me to draw the conclusion that unilateral coronal synostosis should be treated as early as possible not only for cosmetic reasoJas but also for the prevention of parenchymal damage.
A 18-month-old boy was presented with complaints of craniofacial deformities since birth. The pregnancy and delivery had been normal. On admission, neurological examination showed normal psychomotor development, but flattening o f the right frontal region, right exophthalmos, right temporal bulging, and asymmetry of the maxilla and mandible (Figure 1A). X-ray films of the skull revealed absence o f the right coronal suture, elevation of the right sphenoidal ridge, and bulging of the right temporal bone. Computed tomography scans (Figure 2) showed deviation of the right lateral and third ventricles, bowing of the interhemispheric fissure to the left side, and flattening of the frontal bone, suggesting compression of the frontal lobe. In addition, moderate enlargement of the lateral and third ventricles as well as the subarachnoid spaces could be seen, although that immediately beneath the flattened frontal bone was spared. Lateral canthal advancement was carried out to the unilateral coronal synostosis on the left side on N o v e m ber 24, 1981. The photograph (Figure 1B) taken 11 months after the operation shows a disappearance of the craniofacial asymmetry, achieving excellent cosmetic results. His developmental milestones remained normal thereafter. Computed tomography scans (Figure 3) performed 13 months after the operation demonstrated a remarkable reduction of the displacement of the right lateral and third ventricles as well as the interhemispheric fissure, and revealed an elevation of the free bone flap in the frontal region, together with a widening of subarachnoid spaces just beneath it.
KEY WORDS: Craniosynostosis; Unilateral coronal synostosis; Computed tomography; Brain damage, compression
T h e r e are two reasons for carrying out operative treatment of craniosynostosis: first, a cosmetic deformity can be alleviated and, second, impairment of the growing brain can be minimized. It has been questioned whether synostosis of one suture alone can distort the brain sufficiently to produce an abnormality of the central nervous system [4,5]. The above-mentioned concept was, however, the opinion before the advent of the CT scan. T h e r e have been only a few reports assessing the intracranial changes in unilateral coronal synostosis using a CT scan [1]. The author has operated on two patients with unilateral coronal synostosis by means of lateral canthal advancement [2] since the introduction of CT scan. This paper presents the preoperative and postoperative intracranial changes in tihese two cases. In addition, the theoretical basis for th,e treatment of unilateral coronal synostosis is discussed.
Address reprint requests to: Dr. Nobuhiko Aoki, Department of Neurosurgery, Fuchu Metropolitan Hospital, 2-9-2- Musashidai, Fuchu-Shi, Tokyo 183, Japan.
© 1984 by Elsevier Science Publishing Co., Inc.
Case 1
Case 2 A 6-year-old boy was referred for evaluation of craniofacial asymmetry, which had been detected at birth. His mother's pregnancy had been unremarkable as was the delivery. T h e r e was no significant family history. Neurologically, he was assessed to be normal. His craniofacial appearance (Figure 4) was typical of unilateral coronal synostosis, including flattening o f the right fron0090-3019/84/$3.00
250
Surg Neurol 1984;22:249-52
Aoki
A
Figure 1. (A) Preoperative (November 1981) and (B) postoperative (September 1982) photographs in case 1. Prominent asymmetry~ including a flattening on the frontal region, and an exophthalmos on the right side (A), was restored to almost normal (B).
Figure 2 (A-D). Preoperative C T scans in case I showed deviation of the right lateral and third ventricles, bowing of the interhemispheric fissure to the left side, and flattening of the frontal bone. Note enlargement of the ventricles and subarachnoid spaces, sparing that immediately beneath the flattened frontal bone.
tal region, right exophthalmos, and bulging of the temporal region. Plain x-ray films of the skull showed absence of the right coronal suture. Computed tomography scans (Figure 5) revealed displacement of the right lateral and third ventricles to the left side, bowing of the interhemispheric fissure, and flattening of the right frontal bone. They also disclosed moderate enlargement of the ventricles and subarachnoid spaces, without involving the subarachnoid space just beneath the depressed
Figure 3. Postoperative C T scan in case 1 (after 13 months) demonstrated a reduction of the distortion. Note an elevation of the free boneflap, together with a widening of subarachnoid spaces just under it.
Unilateral Coronal Synostosis
A
frontal bone. H e underwent a lateral canthal advancement for the right unilateral coronal synostosis on September 8, 1981. Computed tomography scans performed 3 months after the operation (Figure 6) showed a reduction of the displacement of the right lateral and third ventricles as wel]i as the interhemispheric fissure, an elevation of the free bone flap in the right frontal region, with a widening o f the subarachnoid spaces immediately beneath it. The photograph taken 20 months after the operation (Figure 4B) revealed complete restoration o f the craniofacial symmetry. His psychomotor developmental milestones remained normal.
Surg Neurol 1984;22:249-52
251
B
Figure 4. Preoperative (A) and postoperative (B) photographs in case 2, showing a symmetrical restoration by lateral cathal advancement. Discussion According to Matson, it is highly questionable whether or not synostosis o f one suture alone can distort the brain sufficiently to produce any general or focal abnormality of the central nervous system; therefore, its treatment is performed exclusively for cosmetic reasons [4]. Similarly, Milhorat states that in patients with premature closure of one cranial suture, the considerations are mainly cosmetic, and operations for stenosis of a single coronal suture performed 9 months after birth
Figure 5. Preoperative C T Jcans in case 2 showed a displacement of the right lateral and third ventricles as well as the interhemispheric fissure to the left side. In addition, th 0 revealed a moderate enlargement of the ventricles and subarachnoid spaces, without involving the subarachnoid space immediately beneath the depressed frontal bone.
Figure 6. Postoperative C T scans in case 2 demonstrated a reduction of the parenchymal deformities, and a widening of the subarachnoid space just under the elevated bone flap.
252
Surg Neurol 1984;22:249-52
usually do not restore normal cranial configuration [5]. Thus, it has been regarded that synostosis of one suture alone may not produce brain damage, but this opinion preceded the advent o f CT scan. Recently, it became apparent that when a coronal suture fuses, the frontosphenoidal and frontoethomoidal sutures close as well [2,8]. Based on their combination, unilateral coronal synostosis is not a synostosis of a single suture, but of multiple sutures. From these reasons, Hoffman and Mohr proposed lateral canthal advancement o f the supraorbital margin [2] and Marsh and Schwartz evolved a further extended procedure [3]. M o r e recently, Carmel et al evaluated intracranial changes in nine cases with unilateral coronal synostosis by CT scan [1]. T h e y showed the probability of some degree of parenchymal damage by local compression due to the foreshortened frontal base and flattened frontal calvarium. C o m p u t e d tomographic appearances in both o f our patients presented here are almost the same as those o f Carmel et al: local pressure on the frontal lobe and a definite shift o f the midline structures. These gross deformities of the brain are considered to be produced by compression of the frontal bone because they can restore a normal configuration by treatment with lateral canthal advancement. In postoperative CT scans, there appears a prominent cerebrospinal fluid space at the site of a formerly fused coronal suture. Carmel et al speculated that this is caused either by expansion of the decompressed cerebrospinal fluid pathways into an open bony defect or by local brain atrophy [1]. Similar computed tomographic findings were obtained in both patients in this paper. It seems unlikely, however, that the dilatation of the spaces under the formerly fused suture is produced by local atrophy, because it was associated with a definite elevation of the free bone flap in both patients. It is reasonable to consider that the dilatation is caused by the
Aoki
restoration of cerebrospinal fluid circulation, which is the result of decompression at the fused site by lateral canthal advancement. T h e elevation o f the free bone flap and restoration of shift of midline structure imply that unilateral coronal synostosis may, at least morphologically, be significantly harmful to the developing brain in infants. In addition, these c o m p u t e d tomographic findings may support the concept insisted upon by M o h r et al [6] and Renier et al [7] that intracranial hypertension can develop in cases with unilateral coronal synostosis. It is not definite whether unilateral coronal synostosis can actually produce brain damage. Based on computed tomographic appearances seen in this report, however, it is concluded that patients with unilateral coronal synostosis should be treated as early as possible not only for cosmetic reasons but also to prevent any possible harm to the growing and developing brain. References 1. Carmel pw, Luken MG III, Ascherl GF, Jr. Craniosynostosis: Computed tomographic valuation of skull base and calvarial deformities and associated intracranial changes. Neurosurgery 1981;9:366-72. 2. Hoffman HJ, Mohr G. Lateral canthal advancement of the supraorbital margin: a new corrective technique in the treatment of coronal synostosis.J Neurosurg 1976;45:376-81. 3. Marsh JL, Schwartz HG. The surgical correction of coronal and metopic craniosynostosis.J Neurosurg 1983;59:245-51. 4. Matson DD. Neurosurgery of infancy and childhood. Ed 2. Springfield, Ill: CC Thomas, 1969:122-67. 5. Milhorat TH. Pediatric neurosurgery. Philadelphia: FA Davis, 1978:171-90. 6. Mohr G, Hoffman HJ, Munro IR, et al. Surgical management of unilateral and bilateral coronal synostosis: 21 years of experience. Neurosurgery 1978;2:83-92. 7. Renier D, Sante-Rose C, Marchac D, Hirsch J. Intracranial pressure in craniostenosis. J Neurosurg 1982;57:370-7. 8. Seeger JF, Gabrielsen TO. Premature closure of the frontosphenoidal suture in synostosis of the coronal suture. Radiology 1971;101:631-5.