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Congenital cytomegalovirus infection and hydranencephaly
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Radiography (1996) 2, 229-232 CASE R E P O R T
CONGENITAL CYTOMEGALOVIRUS INFECTION AND HYDRANENCEPHALY R. Nuri Sener Department of Radiology, Ege University Hospital Bornova, Izmir, 35100, Turkey (Received 26 September 1995; accepted 26 March 1996)
The cause of hydranencephaly is not yet clear. Experimental occlusion of the supraclinoid carotid arteries may lead to this condition. Toxoplasmosis and cytomegalovirus (CMV) infections have also been considered to be causative factors. We describe computed tomography (CT) and magnetic resonance (MR) imaging findings in a patient with both CMV and hydranencephaly, as further evidence of a possible causal relationship between the two conditions. The clinico-radiologic findings favoured a CMV infection with concomitant occlusion of the supraclinoid carotid arteries during the late intrauterine period. Key words: computed tomography; magnetic resonance imaging; cytomegalovirus; hydranencephaly.
INTRODUCTION Congenital cytomegalovirus (CMV) infection has previously been suggested to be the possible cause of disorders such as neuronal migrational anomalies and encephaloclastic disorders including hydranencephaly [1-3]. We describe a patient with both C M V and hydranencephaly, possibly representing further evidence of a causal relationship between the two conditions.
CASE REPORT A 14-month-old boy presented with severely retarded m o t o r development. The head circumference was normal, but hepatosplenomegaly was noted. Serologic tests for C M V infection were positive. Anti-CMV l g G titres were studied using a microenzyme immune assay. An initial anti-CMV I g G titre value of 1:1600 showed a fivefold increase over 4 months. A cranial CT study revealed that most of the cerebral hemispheres were replaced by cerebrospinal fluid (CSF). Calcifications were noted in the remnants of the cerebral tissue, especially at the right lateral ventricular region (Fig. 1), which were possibly due to CMV infection. The parietal lobes and most of the temporal and frontal lobes were absent. The occipital lobes and thalami and basal ganglia were preserved, and the falx was intact. The posterior fossa was normal, as was the third ventricle. In addition to these findings, magnetic resonance imaging (MRI) revealed the absence of the cortical mantle in most of the supratentorial regions, intact meninges and a thinning of the body of the corpus callosum, indicating hydranencephaly [Fig. 2(a) (c)]. A shunt tube was placed into the cranium to exclude the possibility of a massive hydrocephalus. © 1996 The College of Radiographers
1078-8174/96/030229+04 $18.00 229
230
Nuri Sener
Figure 1. CT scan (without contrast medium) showing calcificationssuggestingCMV in the remnants of the cerebral tissue at the right periventricular region (arrows). The parietal lobes are absent as are most of the frontal lobes, this accounts for the dilatation of the lateral ventricles.
This procedure was ineffective (i.e. there was no re-expansion of a n y b r a i n mantle) further c o n f i r m i n g the diagnosis of h y d r a n e n c e p h a l y .
DISCUSSION C M V is the m o s t c o m m o n cause of congenital infection caused by a D N A virus belonging to the herpes virus group. T h e c o n d i t i o n occurs by t r a n s p l a c e n t a l virus transmission. The target cells of C M V are the i m m a t u r e cells of the germinal matrix, resulting in widespread periventricular i n f l a m m a t i o n , tissue necrosis a n d s u b s e q u e n t dystrophic calcification. I n early gestation there can be n e u r o n a l m i g r a t i o n a l anomalies a n d later infections can cause encephaloclastic disorders such as s u b e p e n d y m a l p a r a v e n t r i c u l a r cysts, h y d r a n e n c e p h a l y a n d micrencephaly [1 3]. I n our p a t i e n t the diagnosis of C M V was indicated by serological tests a n d by the typical periventricular calcification pattern.
Figure 2.
(~-c). MR images. (a) Tl-weighted inversion recovery (TR/TI/TE, 2800/800/30; one excitation) axial section at the level of the thalami. (b) Tl-weighted spin-echo (TR/TE, 600/20; two excitations) axial section at the level of the parietal bones. (c) Tl-weighted spin-echo (TR/TE, 500/20; two excitations) mid-sagittal section. The parietal lobes, and most of the frontal and temporal lobes are absent (a~c). The falx is intact, excluding alobar holoprosencephaly (b). The meninges are intact (arrows) (b). The posterior fossa, occipital lobes, and the thalami and basal ganglia are preserved (a-c). The body of the corpus callosum shows apparent thinning (arrow) compared to the genu and splenium, which indicates an ischaemic-encephaloclastic disorder affecting this structure, representing a secondary finding signifying the aetiology of hydranencephaly as occlusion of the supraclinoid carotid arteries in the late intrauterine period. Thus, the clinico-radiologicfindings in this patient indicate a CMV infection with concomitant occlusion of the supraclinoid carotid arteries.
CM V and Hydranencephaly
231
232
Nuri Sener
Hydranencephaly is a global encephaloclastic disorder in which most of the cerebral hemispheres have been destroyed and replaced by membraneous sacs (leptomeninges) filled with CSF. The condition is thought to develop in the third to sixth months of gestation. In imaging studies cerebral hemispheres appear to be almost completely replaced by CSF. The thalami are usually preserved, and there is no thalamic fusion, the falx is intact differentiating the condition from alobar holoprosencephaly. The basal ganglia, and inferior frontal and temporal lobes may be preserved partially. The vertebral arteries are intact, usually the cerebellum, pons and midbrain are preserved, although sometimes they may be atrophic. It is very important to differentiate hydranencephaly from severe hydrocephalus, which is best seen by MRI. If radiological interpretation is not straightforward, a CSF diversion procedure may be considered. If this is ineffective (i.e. no re-expansion of any brain mantle) hydranencephaly is indicated [4-6]. In our patient, MRI revealed the complete absence of the parietal and most of the temporal and frontal lobes. The falx and meninges were intact. The body of the corpus callosum showed apparent thinning compared to the genu and splenium, an appearance which was in favour of an ischaemic-encephaloclastic disorder affecting this structure similar to that commonly seen in patients with periventricular leukomalacia. These findings indicated a diagnosis of hydranencephaly. Although the cause of hydranencephaly is not yet clear, occlusion of the supraclinoid carotid arteries has been considered to lead to this condition in experimental studies [W6]. Toxoplasmosis and CMV have also been demonstrated to be causative factors in at least some cases [1]. The clinico-radiologic findings in our patient favour CMV with concomitant occlusion of the supraclinoid carotid arteries. REFERENCES
1. Friede RL, Mikolasek J. Postencephalitic porencephaly, hydranencephaly or polymicrogyria. A review. Acta Neuropathol 1978; 43: 161-8. 2. Becker LE. Infections of the developing brain. Am J Neuro Radiol 1992; 13:537 49. 3. Osborn AG. Diagnostic neuroradiology. St Louis, MO: Mosby, 1994; 674. 4. Barkovich AJ. Pediatric neuroimaging. New York: Raven, 1995; 109 10. 5. Wolpert SM, Barnes PD. M R I in pediatric neuroradiology. St Louis, MO: Mosby, 1992; 107-8. 6. Halsey J, Allen N, Chamberlain HR. The morphogenesis of hydranencephaly. J Neurol Sci 1971; 12: 187-217.
R A ;IRA
LLEG
E
OF
PH ERS
Radiography (1996) 2, 229-232 CASE R E P O R T
CONGENITAL CYTOMEGALOVIRUS INFECTION AND HYDRANENCEPHALY R. Nuri Sener Department of Radiology, Ege University Hospital Bornova, Izmir, 35100, Turkey (Received 26 September 1995; accepted 26 March 1996)
The cause of hydranencephaly is not yet clear. Experimental occlusion of the supraclinoid carotid arteries may lead to this condition. Toxoplasmosis and cytomegalovirus (CMV) infections have also been considered to be causative factors. We describe computed tomography (CT) and magnetic resonance (MR) imaging findings in a patient with both CMV and hydranencephaly, as further evidence of a possible causal relationship between the two conditions. The clinico-radiologic findings favoured a CMV infection with concomitant occlusion of the supraclinoid carotid arteries during the late intrauterine period. Key words: computed tomography; magnetic resonance imaging; cytomegalovirus; hydranencephaly.
INTRODUCTION Congenital cytomegalovirus (CMV) infection has previously been suggested to be the possible cause of disorders such as neuronal migrational anomalies and encephaloclastic disorders including hydranencephaly [1-3]. We describe a patient with both C M V and hydranencephaly, possibly representing further evidence of a causal relationship between the two conditions.
CASE REPORT A 14-month-old boy presented with severely retarded m o t o r development. The head circumference was normal, but hepatosplenomegaly was noted. Serologic tests for C M V infection were positive. Anti-CMV l g G titres were studied using a microenzyme immune assay. An initial anti-CMV I g G titre value of 1:1600 showed a fivefold increase over 4 months. A cranial CT study revealed that most of the cerebral hemispheres were replaced by cerebrospinal fluid (CSF). Calcifications were noted in the remnants of the cerebral tissue, especially at the right lateral ventricular region (Fig. 1), which were possibly due to CMV infection. The parietal lobes and most of the temporal and frontal lobes were absent. The occipital lobes and thalami and basal ganglia were preserved, and the falx was intact. The posterior fossa was normal, as was the third ventricle. In addition to these findings, magnetic resonance imaging (MRI) revealed the absence of the cortical mantle in most of the supratentorial regions, intact meninges and a thinning of the body of the corpus callosum, indicating hydranencephaly [Fig. 2(a) (c)]. A shunt tube was placed into the cranium to exclude the possibility of a massive hydrocephalus. © 1996 The College of Radiographers
1078-8174/96/030229+04 $18.00 229
230
Nuri Sener
Figure 1. CT scan (without contrast medium) showing calcificationssuggestingCMV in the remnants of the cerebral tissue at the right periventricular region (arrows). The parietal lobes are absent as are most of the frontal lobes, this accounts for the dilatation of the lateral ventricles.
This procedure was ineffective (i.e. there was no re-expansion of a n y b r a i n mantle) further c o n f i r m i n g the diagnosis of h y d r a n e n c e p h a l y .
DISCUSSION C M V is the m o s t c o m m o n cause of congenital infection caused by a D N A virus belonging to the herpes virus group. T h e c o n d i t i o n occurs by t r a n s p l a c e n t a l virus transmission. The target cells of C M V are the i m m a t u r e cells of the germinal matrix, resulting in widespread periventricular i n f l a m m a t i o n , tissue necrosis a n d s u b s e q u e n t dystrophic calcification. I n early gestation there can be n e u r o n a l m i g r a t i o n a l anomalies a n d later infections can cause encephaloclastic disorders such as s u b e p e n d y m a l p a r a v e n t r i c u l a r cysts, h y d r a n e n c e p h a l y a n d micrencephaly [1 3]. I n our p a t i e n t the diagnosis of C M V was indicated by serological tests a n d by the typical periventricular calcification pattern.
Figure 2.
(~-c). MR images. (a) Tl-weighted inversion recovery (TR/TI/TE, 2800/800/30; one excitation) axial section at the level of the thalami. (b) Tl-weighted spin-echo (TR/TE, 600/20; two excitations) axial section at the level of the parietal bones. (c) Tl-weighted spin-echo (TR/TE, 500/20; two excitations) mid-sagittal section. The parietal lobes, and most of the frontal and temporal lobes are absent (a~c). The falx is intact, excluding alobar holoprosencephaly (b). The meninges are intact (arrows) (b). The posterior fossa, occipital lobes, and the thalami and basal ganglia are preserved (a-c). The body of the corpus callosum shows apparent thinning (arrow) compared to the genu and splenium, which indicates an ischaemic-encephaloclastic disorder affecting this structure, representing a secondary finding signifying the aetiology of hydranencephaly as occlusion of the supraclinoid carotid arteries in the late intrauterine period. Thus, the clinico-radiologicfindings in this patient indicate a CMV infection with concomitant occlusion of the supraclinoid carotid arteries.
CM V and Hydranencephaly
231
232
Nuri Sener
Hydranencephaly is a global encephaloclastic disorder in which most of the cerebral hemispheres have been destroyed and replaced by membraneous sacs (leptomeninges) filled with CSF. The condition is thought to develop in the third to sixth months of gestation. In imaging studies cerebral hemispheres appear to be almost completely replaced by CSF. The thalami are usually preserved, and there is no thalamic fusion, the falx is intact differentiating the condition from alobar holoprosencephaly. The basal ganglia, and inferior frontal and temporal lobes may be preserved partially. The vertebral arteries are intact, usually the cerebellum, pons and midbrain are preserved, although sometimes they may be atrophic. It is very important to differentiate hydranencephaly from severe hydrocephalus, which is best seen by MRI. If radiological interpretation is not straightforward, a CSF diversion procedure may be considered. If this is ineffective (i.e. no re-expansion of any brain mantle) hydranencephaly is indicated [4-6]. In our patient, MRI revealed the complete absence of the parietal and most of the temporal and frontal lobes. The falx and meninges were intact. The body of the corpus callosum showed apparent thinning compared to the genu and splenium, an appearance which was in favour of an ischaemic-encephaloclastic disorder affecting this structure similar to that commonly seen in patients with periventricular leukomalacia. These findings indicated a diagnosis of hydranencephaly. Although the cause of hydranencephaly is not yet clear, occlusion of the supraclinoid carotid arteries has been considered to lead to this condition in experimental studies [W6]. Toxoplasmosis and CMV have also been demonstrated to be causative factors in at least some cases [1]. The clinico-radiologic findings in our patient favour CMV with concomitant occlusion of the supraclinoid carotid arteries. REFERENCES
1. Friede RL, Mikolasek J. Postencephalitic porencephaly, hydranencephaly or polymicrogyria. A review. Acta Neuropathol 1978; 43: 161-8. 2. Becker LE. Infections of the developing brain. Am J Neuro Radiol 1992; 13:537 49. 3. Osborn AG. Diagnostic neuroradiology. St Louis, MO: Mosby, 1994; 674. 4. Barkovich AJ. Pediatric neuroimaging. New York: Raven, 1995; 109 10. 5. Wolpert SM, Barnes PD. M R I in pediatric neuroradiology. St Louis, MO: Mosby, 1992; 107-8. 6. Halsey J, Allen N, Chamberlain HR. The morphogenesis of hydranencephaly. J Neurol Sci 1971; 12: 187-217.