Pediatr Radiol (1991) 21:189-192

Pediatric Radiology 9 Springer-Verlag 1991

Originals Transient gyriform brightness on non-contrast enhanced computed tomography (CT) brain scan of seven infants P. J. Close and H. M. Carty Royal Liverpool Childrens Hospital, Liverpool, UK Received: 7 April 1990; accepted: 25 June 1990

Abstract. S p o n t a n e o u s g y r i f o r m b r i g h t n e s s s e e n on C T scan is an u n u s u a l finding unless a s s o c i a t e d with arteriovenous malformations (AVM). There are sporadic case r e p o r t s in t h e l i t e r a t u r e o f its o c c u r r e n c e in associa t i o n with h e r p e x s i m p l e x virus e n c e p h a l i t i s ( H S V E ) , purulent meningitis, f o l l o w i n g c h e m o t h e r a p y for l e u k a e m i a , in a child with c h r o n i c r e n a l failure, a n d in a child with folic acid deficiency. W e p r e s e n t a series of s e v e n cases e x h i b i t i n g this p h e n o m e n o n , n o n e of w h o m h a v e A V M s , w h o h a v e b e e n s c a n n e d at this h o s p i t a l in t h e first 21/2 y e a r s following the i n s t a l l a t i o n of a C T scanner. F o u r of t h e cases h a d c o n g e n i t a l h e a r t d i s e a s e r e q u i r ing c o r r e c t i v e s u r g e r y o r c a r d i a c c a t h e t e r i s a t i o n . T h e o t h e r t h r e e h a d p r o b a b l e m e n i n g o - e n c e p h a l i t i s . I n all cases the g y r i f o r m b r i g h t n e s s f o l l o w e d a n i s c h a e m i c insult to the child's brain. W e h y p o t h e s i s e t h a t this p h e n o m e n o n is an i s c h a e m i c r e s p o n s e in t h e i m m a t u r e b r a i n

a n d t h a t its o c c u r r e n c e is n o t so r a r e as t h e l i t e r a t u r e m a y suggest.

Materials and methods The names of the seven infants were obtained from the CT register. These represent all known cases demonstrating this spontaneous gyral brightness on brain CT scan performed at this hospital in the first thirty months following installation of the CT scanner. The medical records and CT scans were reviewed. Details of the initial illness, management and the outcome of mental and physical development were obtained from the records. One child died but autopsy was refused. All children had serial scans at varying intervals. The evolution and progression of abnormalities has been documented and correlated with the clinical outcome.

Table 1. See text Case 1

Age at presentation 8 months

2 3

4

Indication for CT

Time of scans re. illness

Mental development/outcome

Post-operative (cardiac) convulsions and rigidity

i month 9 months

Severe global retardation Visual impairment

7 months

Post-operative (cardiac) spasticity

3 weeks

Epilepsy

7 months

Post cardiac-catheterization hemiplegia

2 days 2 weeks 5 weeks

Left hemiplegia

15 days

Abnormal head ultrasound ? cause

15 days

Moderate delay in attainment of developmental milestones

5

4 weeks

Ventriculitis. Poor response to therapy

4 weeks 4z/2 weeks 6 months

Severe global retardation

6

4 months

Collapse and convulsions ? cause

i day 3 days 7 days 3 months

Severe global retardation

7

17 months

Collapse and convulsions ? meningitis

4 days 2 weeks 4 months

Right hemianopia and mild right hemiplegia

E J. Close and H. M. Carty: Gyriform brightness on brain CT scan

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Fig.la-c. 17-month-old boy with meningococcal infection, aScan

Results The age of presentation, indication for CT scan, time of scan in relation to the onset of the illness and subsequent mental development of each case is presented in Table 1. The clinical illness and treatment is presented in Table 2. Figures 1-3 illustrate typical appearances. Early changes are non-specific with evidence of cerebral o e d e m a and loss of grey-white matter differentiation. T h e r e are multiple low-attenuation areas which tend to be extensive. F r o m approximately two weeks after the precipitating event, gyriform brightness is seen on non contrast enhanced scans related to areas of low attenuation. This appearance may be permanent, but in three of the seven cases the gyriform brightness has disappeared after approximately four to nine months. Other late appearances are focal or generalised cerebral atrophy, ventricular dilatation and large areas of low density. Islands of brightness without contrast enhancement may occur within the low attenuation areas. Prognosis is poor. The affected infants have b e e n left with a degree of mental retardation or physical disability, depending on which area of cerebral cortex has b e e n involved. Case 4 is possibly an exception, as to date he shows only moderate delay in attainment of his developmental milestones. However, the oldest child is only three at present and full assessment of mental ability and neurological well being of young children is difficult.

Discussion Gyriform brightness of this type is an unusual phenomenon unless associated with AVMs. A review of the literature for other causes has revealed only sporadic case reports, usually in association with intracranial infections.

without contrast 4 days after admission. Extensive area of low attenuation in left cerebral hemisphere. Compression of the lateral ventricle, b Scan after 2 weeks. No contrast. Widespread gyriform brightness in corresponding area. c Scala after 4 months. No contrast. No gyriform brightness. Low attenuation area with some ventricular dilatation

Fig.2a-e. 8-month-old girl, unwell after cardiac surgery, a With contrast. 1 month after surgery. Parieto-occipital gyriform brightness with a focus of calcification. Dilated ventricles, b No contrast. Parieto-occipital gyriform brightness with associated low density areas. Extensive brightness over the vertex, c Scan 9 months later. No contrast. The gyriform brightness has disappeared and there are cystic collections at corresponding sites. Evidence of generalized cerebral atrophy and ventricular dilatation

We have been unable to trace any reported cases following surgery or cardiac catheterisation. There are a n u m b e r of well d o c u m e n t e d case reports of infants with herpex simplex virus encephalitis (HSVE) developing gyriform calcification [1-5]. Eyster and Margolis [3] reported a case in neonate who had contracted intrauterine infection from herpes simplex. Brain biopsy revealed a severe diffuse necrotizing process with extensive calcification of the necrotic tissue. Sugimoto et al. [2] reported CT scan appearances of eight infants with H S V E , two of which developed gyriform calcification. Taccone et al. [1] reported a series of nine infants with H S V E with two cases showing bilateral gyriform calcifications. The evolution of changes were not discussed. Both groups of authors suggested that the findings, in association with the other CT abnormalities which they described, supported the idea that H S V E in young children is a primary diffuse haemorrhagic necrotizing encephalitis based on brain immaturity. Yamanouchi et al. [6] reported transient bilateral gyriform calcification in a two month old baby after purulent

TabLe2. See text Case 1

3

Clinical problem CHD - Common atrium PAVD Mitral regurgitation CHD - AV septal defect PDA Pulmonary hypertension CHD - Transposition VSD PS CHD - Coarctation and PDA Posterior urethral valves Sacral meningocoelc Ventriculitis Collapse and convulsions ? Reyes syndrome ? encephalitis Meningococcal meningitis and septicaemia

Treatment Corrective heart surgery

Indication for CT scan Rigidity and convulsions post-operatively

Corrective heart surgery

Cardiac arrest postoperatively. Subsequent spasticity

Cardiac catheterization

Hemiparesis apparent 48 h later

Subsequently underwent corrective surgery

Ventriculomegaly noted on head ultrasound

Supportive treatment on ICU

Coma

Supportive treatment on ICU

Supportive treatment on ICU

Convulsions Coma Convulsions Diagnostic purposes Coma Convulsions

E J. Close and H. M. Carty: Gyriform brightness on brain CT scan

Fig.3 a-c. 7-month-old girl after uneventful cardiac catheterization. a Scan 2 weeks after catheterization. No contrast. Gyriform brightness in left frontal and occipital lobes. Low density area in right frontal lobe with slight mid-line shift and faint brightness, b Scan

191

1 month later. Faint residual gyriform brightness in left occipital and frontal lobes. Large low density area in right frontal parietal lobe. e Scan same time as b with contrast. Large right fronto-parietal low attenuation area with focus of brightness

192 meningitis. The calcification reabsorbed over a four and a half month period. This child had a craniotomy for treatment of a subdural effusion which revealed a muddy grey exudate in the subarachnoid space. The underlying gyri were flat and discoloured. Histologically the cerebral substance had lost its characteristic structure and contained loci of calcification. They speculate that the greyish exudate was responsible for the gyriform calcification and that surgical washing at operation and subsequent giant cell and macrophage action made it a transient phenomenon. There are two other case reports of tram-line and convoluted calcification following purulent meningitis [7,11]. In addition to intracranial infection, there are reports of its occurrence in children with leukaemia receiving intrathecal methotrexate and irradiation [8, 9]. Garwicz and Mortensson [8] reported two cases, one receiving the above therapy for leukaemia. The other was a child with epilepsy and coeliac disease who developed gyriform calcification, after anticonvulsant therapy. They hypothesised that the calcification may be secondary to folic acid deficiency interfering with metabolism in the central nervous system. Swartz et al. [10] reported curvilinear cortical calcifications in a five year old child with chronic renal failure. Two of our cases were severely ill with proven intracranial infection (Cases 5 and 7), while Case 6 had probable encephalitis or possible Reyes syndrome (no definitive diagnosis could be made). All three required supportive treatment on ICU following lengthy periods of shock and collapse. Four cases (Cases 1-4) had complex congenital heart disorders, causing episodes of heart failure. Cases i and 2 underwent corrective heart surgery on bypass, and subsequently developed neurological signs in the post-operative period. In Case 2 this followed a brief episode of cardiac arrest on the first post-operative day with an anaesthetist present who provided rapid resuscitative treatment. Case 3 required diagnostic cardiac catheterization but developed a hemiparesis two days afterwards. Interestingly, Case 4 had a P D A with coarctation of the aorta and was in mild heart failure when head ultrasound was performed as part of general investigation. H e was neurologically asymptomatic, but ventriculomegaly was demonstrated which prompted the request for CT brain scan. Therefore a common link with our series is a probable transient ischaemic insult to the immature brain, which subsequently results in gyriform brightness. Case 4 demonstrates that this insult can pass unnoticed clinically, but was presumably a result of hypoxaemia secondary to heart failure. A recent case report [12] describes calcification of the basal ganglia in a six month old baby after the 'near miss syndrome'. If ischaemia is the cause then it is surprising that so few case reports have appeared in the lit-

R J. Close and H. M. Carty: Gyriform brightness on brain CT scan erature. Possibly it is the timing of the CT scan in relation to the illness which is important, as we have shown that gyriform brightness is transitory. A probable explanation for the appearance is that the high density appearance of the gyri is due to haemorrhage into the gyri with haemosiderin deposition. Density measurements of the lesions ranged between seventy to ninety-five, so the lesions are not solid calcific nodules. The subsequent disappearance of the increased density also suggests a haemorrhagic theory as solid calcification would not resolve in a similar manner. We were unable to get histological proof of this, but it should be possible to confirm the haemorrhagic nature by MRI. We do not have access to such facilities. The p h e n o m e n o n has not been observed above the age of two. This is also the experience of other workers (Kendall, personal communication) and appears to be an ischaemic response of the infant brain.

References 1. Taccone A, Gambaro G, Ghiorzi M, Gianbartolomei G, Rolando S, Fondelli P (1988) Computed tomography (CT) in children with herpes simplex encephalitis. Pediatr Radio119:9 2. Sugimoto T, Okazaki H, Nishida N, Hara T, Yasuhara A, Kasahara M, Kobayashi Y (1985) Computed tomography in young children with herpes simplex virus encephalitis. Pediatr Radiol 15:372 3. Eyster El=',Margolis M Th (1971) Progressive cortical calcification in a newborn. Report of a case. Neuroradiology 2:115 4. Ketonen L, Koskiniemi M-L (1983) Gyriform clacification after herpes simplex virus encephalitis. J Comput Assist Tomogr 7: 1070 5. Williams JR Fowler GW (1972) Gyriform calcification following encephalitis. Neuroradiology 4:57 6. Yamanouchi Y, Someda K, Tani S, Kawamura Y, Matsumura H (1980) Gyriform calcification after purulent meningitis. Neuroradiology 20:159 7. Watanabe N, Kimura A (1975) Intracranial calcifications with severe brain atrophy following purulent meningoencephalitis. Jpn J Pediatr 29:71 8. Garwicz S, Mortensson W (1976) Intracranial calcification mimicking the Sturge-Weber syndrome. Pediatr Radiol 5:5 9. Borns PF, Rancier LF (1974) Cerebral calcification in childhood leukaemia mimicking Sturge-Weber syndrome. Am J Roentgenol Radium Ther Nucl Med 122:52 10. Swartz JD, Faeber EN, Singh N, Polinsky MS (1983) CT demonstration of cerebral subcortical calcifications. J Comput Assist Tomogr 7:476 11. Adoyle A, Bohrer S (1971) Intracranial 'tram-like' calcification in purulent meningitis. West Afr Med J 20:195 12. Fasanelli S, Perrotta F, Fruhivirth R (1989) Computed tomography of the 'near miss syndrome' with basal ganglion calcification. Pediatr Radio119:435 g J. Close, M. D. Royal Liverpool Children's Hospital Alder Hey Liverpool, L12 2AP UK