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Rett syndrome: Cerebellar pathology
Rett Syndrome: Cerebefar Pathology A n d e r s O l d f o r s , M D , P h D * , P a t r i c k S o u r a n d e r , M D , P h D * . D a w n a L. A r m s t r o n g , M D ; , A l a n K. Percy, MD*, I n g e g e r d W i t t - E n g e r s t r 6 m , MD§, a n d B e n g t A. H a g b e r g , M D , PhD.~
The cerebellar pathology at autopsy of 5 patients with Rett syndrome is described. The patients ranged in age from 7-30 years. All had markedly reduced brain weights with proportionately small cerebella. Microscopic examination revealed loss of Purkinje cells, atrophy, astrocytic gliosis of the molecular and granular cell layers, and gliosis and loss of myelin in the white matter. Cortical atrophy occurred focally along the folia and was often more marked in the tips of the folia. The 2 oldest patients had been treated with phenytoin which may have contributed to the morphologic changes. Atrophy and gliosis increased with age or in patients without phenytoin treatment; the youngest patient demonstrated only minor microscopic changes. In addition to the generalized alterations, 1 patient had several adjacent folia with severe atrophy. The results indicate that cerebellar changes in Rett syndrome consist of general hypoplasia with the addition of atrophy beginning in childhood and progressing over many years.
patients and electroencephalograplL~. ~EEG) display,, a progressive pattern: however, smzures often subside with age [7]. Previous neumpathologic studies revealed micrencephaly [8,91. Microscopically, hypopigmentation of the substantia nigra has been described m most patients. In addition, the mconsistem occurrence of mild. diffuse cortical atrophy, mild gliosis, and mikl. Iocal ,',pongy aherations of the white matter has been reported [8,9]. In a recent study,, Oldfors et al. reported rnorphologic alterations in the spinal cord with astroc~ tic cellular and fibrillary gliosis and signs of degeneralion of both white and gray matter I lOf In spite of early incoordinatton in RS. pathologic findings of the cerebellum have not been described m detail. In our present study, we present the cerebellar pathology of 5 panents 17. t2. 17, 20, and 30 3ears of age) who fulfilled the diagnosnc crileria for RS I 1.12].
Case Reports
Rett syndrome (RS) is a globally distributed disorder with unknown etiology and pathogenesis which thus far is restricted to females [1-4]. The development during early infancy is normal. Even prior to a period of regression, which may last from 1 week to 1 year and features loss of interpersonal contact, acquired single words, and manipulative hand skills, several girls have displayed low muscle tone and poor equilibrium control [5]; however, regression ceases, leaving the child speechless, severely retarded, in an apraxic/dyspraxic state, and often with a characteristic jerky truncal tremor [2-5]. Interpersonal contact gradually improves while speech and hand skills never return. With increasing age, neurologic signs are characterized by the sequential appearance of spasticity, dystonia, rigidity, and weakness and wasting resulting in severe motor disability in most patients [3,4,6]. Epilepsy is present in 90% of the
('ascs S - i 2 . S 2 i . S-35. and (:$4~ h a , : been described previously [10.131. ('ase S-12 1'his patiem was born m 196(~ and died suddenly during a meal at the age of 20 years. Pre- and peri-natal histories were tmevent. ful. She was hypotonic and sat unsteadilx at S mnnths of a.,.z,e. C r a w l i n g never included reciprocal m o v e m e m s of the lower limbs Development phtteaued from 10-21 months of age (Stage I) 141. The regression period (Stage [ll occurred f r o m 13/a-21/'_ ,,x'ar', of age and included withd r a w n affecl and loss of standing, walking, and speech. At 30 m o n m s of age, her tone was decreased and equilibrmm funct nns mtpalred. Truncal ataxia d o m i n a t e d her ~mpalred m o l o r functions and handw r i n g i n g and dyspraxia or apraxia nterlered with her perl~rmance (Stage l i b From S years o f age. she was w h e e l c h a i r - b o u n d tStage lV). Seizures appeared al 22 months of age tot which p h e n y t o m was prescribed fi'om 5L/2-16 years. Plasnla concelrtlatRms on a lew occasions between 10-1 ~ years o f age exceeded the r e c o m m e n d e d Iherap~:utic level. From 13 years of a g e until her death at age 2~}. she was also treated with carbamazepine. {'a.xe S-21. "['his patient was born n 9~,7 and died suddenly o~ acute b r o n c h o p n e u m o n i a at 30 years of age Pre and peri-natal histories were uneventful. Early development v, as slovx and interpersonal contact never reached the intensity o f her siblings. Her best performance. at 7-20 months of a g e (Stage l was that or a 5 q 0 - m o n t h - o l d infant. At 30 m o n t h s of age, she progressed into Stage III and slowly regained s u p l x m e d walking in which limb and truncal ataxia ,aas ~hserved. Her p e r f o r m a n c e was apraxic. By t0 yea~s m age. she ,~as wheelchairhound, wasted, and dystonic (Stage IV~ AI 29 years ol a~ze. she was dystonic, rigid, and calm with a staring, unfathomable gaze. Seizures appeared at 101/2 years of age. Pheuvtoin (8-10 mg/kg) w a s prescribed l i n m 101/>lS years ol age; h o w e v e r fl-om I I years, she was raven 14
F r o m the Departments o f *Pathology a n d ~Pediatrics I1; University of G6teborg; G6teborg, Sweden; Departments of :~Pediatrics and *Pathology; B a y l o r College of Medicine; H o u s t o n , Texas.
C o m m u n i c a t i o n s should be addressed m Dr. Oldfors: D e p a r t m e n t o f Pathology; S a h l g r e n ' s Hospital. S-41345 G6teborg, Sweden. Received M a r c h 19. 1990: accepted Jul~ - 1~9().
OIdfors A, Sourander P, Armstrong DL, Percy AK, WittEngerstr6m I, Hagberg BA. Rett syndrome: Cerebellar pathology. Pediatr Neurol 1990;6:310-4.
Introduction
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B
Figure I. Seclioll.s' through the eerebellar hemi,v~heres" 0/ (At Patient S-21 and :B) Patient S-12 disclosed marked and /b~'al atrophy (arrow). A.B." original magni//cation. ,r2.3.
mg/kg liar I l/_~ years. Other antiepileptic drugs prescribed were pheno~ barbital, primidone, and carbamazepine. Case 5-35. This patient was born in 1977 and died in direct association with an operation for scoliosis at 12 years of age. Pre- and perinatal histories included a cesarean section ti)r placenta previa at 39 weeks gestation. Apgar scores were 9 at I min and 10 at 5 rain. Although she was slightly hypotonic, early development was within the normal range until 9 months of age when stagnation appeared (Stage 1). Her best achievements were in sitting, crawling, and standing, but she could not pull herself to a standing position. She had a pincer grasp, spokc l(I single words, and had good eye contact before regression (Stage IIL which occurred between I ~4-2~/2 years. At 15 months of age, she lost all motor skills, eye contact, and verbalization. Nine months later, she was hypotonic with jerky truncal ataxia: by 3(1 months of age, she was severely limited in all gross and fine motor functions (Stage IV). Deep tendon reflexes were brisk. At 12 years of age, she was severely motor disabled. Neurologic signs included prominenl lower neuron involvement, jerky truncal ataxia, some dyskinetic and dystonic trails, and hyperactive reflexes in the lower limbs. Contact and communication were somewhat improved. Fever-induced seizures occurred at IV4 years, mid epilepsy requiring antiepileptic drugs at 2!/4 years. Carbamazepine and valproate were administered, but not phenytoin. Case US-r~. This patient was born in I969 and died at age 17 years while hospitalized with severe pneumonitis which progressed into a puhnonary abscess, She was born at term and acquired normal milestones until the age of I year when she began head-banging and nailbiting (Stage 1). By age 2 years, her fingers were in continuous activity and her hands were clapping and flapping (Stage IlL Initial language development ceased and communication was lost. She was diagnosed as having infantile autism. By age 4 years, her walking was stiff" and uncoordinated and she fell frequently (Stage III). Independent walking stopped at 7 years of age (Stage IV). Three years later, she had her first generalized tonic-clonic seizure, received phenobarbital for some months, but had no antiepileptic drug therapy until age 14 years. At that point, she was severely motor-impaired with prominent dystonic rigidity but maintained eye contact and an occa-
sional social smile. Ethosuximide was administered with good clinical response. Ca.w US-36. This patient was born in 1982 and died suddenly at 7 years, 2 months of age. She exhibited normal early development for 14 months; however, in retrospect, she had hand and trunk tremors beginning at 12 months. Walking began at 14 months of age, but thereafter developmental progress ceased (Stage I). Between 18-24 months of age (Stage IlL she lost purposeful hand use and communication skills. Typical stereotypic hand-wringing and finger movements appeared. During Stage IlL bruxism (2V2 years), staring spells interpreted as seizures (3 years), and respiratory irregularity (apnea/hyperventilation) and scoliosis (4 years) were observed. EEG at age 3 years revealed multifocal spike-and-wave activity. Phenobarbital was administered but replaced in 1 month by carbamazepine which was withdrawn al age 5 years without apparent return of clinical seizures. During Stage llI, gait was progressively broad-based and apractic. Truncal ataxia increased and independent walking stopped at age 3 years. Her neurologic examination from this time until her death was marked by prominent hypotonia with normal deep tendon reflexes and no clonus. No evidence of dystonia or rigidity appeared.
Neuropathology of Cerebellum The autopsies were performed within 24 hours after death. All patients had severe muscular wasting and scoliosis. The brains were 25-35% smaller than normal and weighed 1,050 gm (S-12), 980 gm (S-21), 900 gm (S-35), 1,010 gm (US-36), and 920 gm (US-6). The cerebella were proportionally small. They were fixed with 4% paraformaldehyde and specimens were embedded in paraffin. For this study, sections from the vermis and both hemispheres of the cerebella were stained with silver impregnation (Palmgren), Luxol fast-blue-cresyl violet, and hematoxylin-van Gieson. Immunohistochemical staining
Oldfors et al: Cerebellum in Rett Syndrome
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of glial fibrillary acidic protein (GFAP, Dakopatts), fibronectin, and collagen IV (Labsystems) were performed with the avidin-biotin complex (ABC) method. Macroscopic Findings. Other than being small, the external surfaces of the cerebella exhibited no obvious morphologic changes. In case S-21, mid-sagittal sections through the vermis had very thin folia of all lobules. Case
312 PEDIATRICNEUROLOGY Vol.6 No. 5
Figure 2. Cerebeilar hemisphere o/'case S-2t. (A) Thin folia n'ith subtotal loss of Purkinje cells and reduction ¢~"white niatter. Lu.~ol fastblue-cresyl violet (LFBCV) stain, i(t3) Absence of Purkinje cells, marked/oss ~] granular cells, and a few remaining Go!gi ceUs. LFBCV stain, (C) Total loss c!( Purkiltje cells hut remaining parallel fibers~ and remtlants of haskets. Palmgren siA,er impregnation (PSI) stain. (D) Higher magnif~t'ation of Figure 2(71 PSI: stain: (E) Thin .f?~lia With marked gliosis qf both medulla and cortea. The g!iosis i~ especially abundant in the PurkiJlje cell layer, lrnmunohistochemicat stai~ ing of GFAP. (F Hi,~her magnification q[ Fi~4ure 2E revealing p 'oliferation of Bergmann glia and ~'adiating glial ~i': brils through the molecular cell layer. Inununohistochemical stainiag o[ GFAP, (G) Subtotal loss q]" axons in the White matter qf.fblia. PSI stain. (H) Astroc~to~Ls atM ghosis q( the white matter, bnmunohistoc'hemical staining of GFAP. Origina/ magn(f~eations: A,E: r40: B,D,F-H: x400: ( ' ~200.
S-12 had minor, generalized atrophy, tn the hemispheres, case S-21 had generalized but mild atrophy of the |otia; case S-12 had focal and marked atrophy corresponding to the inferior semilunar lobule [141 (Fig I)i Cases S-35, US-6, and US-36 had no visible atrophy. L i g h t M i c r o s c o p i c F i n d i n g S . Case S-21 had genea'atized atrophy with loss of Purkinje cells in a patchy distribution.
Several folia had complete loss of Purkinje cells (Figs 2A,2B). The molecular cell layer exhibited loss of nerve cells and gliosis. In some areas, stellate cells, parallel fibers, and basket Ion-nations remained in spite of the loss of Purkinje cells (Figs 2C,2D). Gliosis was marked with proliferation of the Bergmann glia and radiating glial projections through the molecular layer (Figs 2E,2F). The white maner appeared pale with myelin stain; in the atrophied folia, loss of axons was almost complete in some areas. Astrogliosis in the white matter was prominent, especially around blood vessels. The dentate nucleus had a reduced number of nerve cells and abundant astrogliosis. The immunohistochemical study using antibodies to albumin and fibronectin revealed no evidence of leakage of plasma proteins through vessel walls. In case S-12, the cortical and subcortical white maner changes in the hemispheric inlerior semilunar lobule were the same as in the most severely atrophied parts of the brain of case S-21. The remainder of the hemisphere and vermis had a milder degree of cortical atrophy which was often patchy in distribution, but affected the granular, Purkinje, and tnolecular cell layers. Atrophy was often more marked in the tips of the folia. The dentate nucleus was gliotic but there was no obvious loss of nerve cells. In case US-6, the folia were thinner than normal. There was patchy cortical atrophy and astrogliosis as in case S-12, but no folia with complete loss of Purkinje cells or severe atrophy we,'e observed. The white matter revealed loss of myelin, especially in the distal parts of the folia. The dentate nucleus demonstrated gliosis but no obvious loss of nerve cells. In case S-35, the tk)lia were generally thinner than normal. There was a moderate, generalized loss of Purkinje cells. As in the other patients, this change was locally accentuated and often seen in the tips of the folia. The atrophy was accompanied by proliferation of astrocytes with gliosis of all cortical cell layers. The gliosis was less conspicuous than in case US-6. in the bottom of 1 sulcus, there was complete absence of cortical cells in a sharply demarcated area revealing some gliosis. The white matter demonstrated loss of myelin, especially in the distal parts of the folia. The dentate nucleus revealed no changes. In case US-36, there was focally distributed loss of Purkinje cells and mild, focal gliosis of all cortical layers. The white tnatter had a minor degree of gliosis. The dentate nucleus appeared normal. Electron microscopic examination of cases S-12 and S-21 yielded no further inlbmmtion. No inclusions of the type described by Papadimitriou et al. were observed [ 15].
S- 12 displayed a large area of severe focal atrophy in the interior semilunar Iobule at age 20 years. In addition, a local loss or agenesis of a restricted part of the cerebellar cortex was observed in case S-35. The youngest patient (US-36, age 71/2 years) exhibited definite but minor atrophy. From these findings, it is concluded that the cerebellum in these RS patients exhibit both hypoplasia and atrophy. The pathogenesis of these changes is not clear. Early brain growth deficiency may be an essential part of the condition and the possibility of a lack of growth factors has been discussed I4]. Generalized cerebellar atrophy. especially loss of Purkinje cells, is a common finding in epileptic patients in whom it has been proposed that cell death may be due to hypoxia, possibly in combination with long-term overdosage of phenytoin [16-19I. Cerebellar atrophy has also been demonstrated on computed tomography (CT), following a few months of phenytoin treatment without overdose, epilepsy, or anoxia [20], and also after acute phenytoin intoxication [21 ]. The cerebellar changes, which have been reported in association with phenytoin medication, have a morphologic appearance similar to those in our patients 116-17]: however, in our series, only S-12 and S-21 were given phenytoin; the other patients received different antiepileptic drugs. Thus, the conclusion that the severity' of changes increase with age appears justified. In our patients, seizures were never observed before the first cerebellar signs; S-21 and US-6 had their first antiepileptic medication after 10 years of age. It is possible that hypoxia may have occuned during the typical alternating hyperventilation and breath-holding irregularities of RS [22]. However, no evidence of nerve cell death secondary to hypoxia in other parts of the brain, such as the hippocampus, was apparent in any of these 5 patients with RS. It appears that the cerebellar atrophy occurring in RS is not secondary to hypoxia or phenytoin medication, but is part of the primary disease. The multifaceted clinical picture in RS, which is already present in preschool age children, indicates widespread brain involvement. Some of the symptoms and signs in RS, such as the combination of early muscular hypotonia and dysequilibrium signs, are possibly clue to cerebellar dysfunction: however, their correlation, if any, with roof phologic changes is not proved.
This study was supported by the Swedish Medical Research Council (Project Number 07122), USPHS HD 24234, the S~.ivstaholm Association. tile Swedish Society for Medical Research. tile Sigurd and Elsa Golje Memorial Foundation. tile First of May Flower Annual Campaign for Children's Health, and the Jerring Foundation.
Discussion
Both the cerebrum and the cerebellum were considerably smaller than normal in all of our RS patients. Microscopically, the cerebellar abnormalities consisted of cortical atrophy and gliosis in a patchy distribution as well as loss of myelin and axons in the white matter. The degree of these alterations increased with age. Furthermore, case
References
[i] Rett A. Uber ein cerebral-atrophisches syndronl hei hyperammon~mie. Brf.ider Hollinek: Verlag, Wien 1966;1-68. I2] Hagberg BA, Aicardi J, Dias K, Ramos O. A progressive syndrome of autism, dementia, ataxia and loss of purposeful handuse in girls: Rett's syndrome: Report of 35 cases. Ann Neurol 1083; 14:471-9.
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[31 Hagberg BA, Witt-Engerstr6m 1, Rett syndrome: A suggested staging system for describing impairment profile with increasing age to,aards adolescence+ Am J Med Genet 1986:24:47-5eL 14t Hagberg BA. Rett syndrome: Clinical peculiarities, diagnosliL approach, and possible cause. Pediatr Neurol 1989;5:75-83. 151 Witt-Engerstr6m 1. Nell syndrome: A retrospective pilot study on potential early predictive symptomatology. Brain Dev 1987;9:481-6. I6] Witl-Engerstrom 1, Hagberg BA. Retl syndrome: Gross motol disability and neural impairment in adults. Brain Dev 1990; 12:23-6. [71 Hagne I, Witt-Engerstr6m l, Hagberg BA. EEG development ill Rett syndrome. A study' of 3(I cases, Electroencephalogr Clin Neurophysiol 1989:72: 1-6. 181 Jellinger K, Seitelberger F. Neumpathology of Relt syndrome. Am J Med Genet 1986:24:259-88. [91 JeUinger K. Armstrong D, Zoghbi HY, Percy AK. Neuropathol ogy of Relt syndrome. Acla Neuropathol 1988:76:142-58. [10] Oldfors A. Hagberg BA, Nordgren H, Sourander P, WillEngerstrhm 1. Rett syndrome: Spinal cord neumpathology. Pediatr Neurol 1988;4:172-4. Jill Hagberg BA, Goutibres F, Hanefeld F, Rett A, Wilson ,t. Ren syndrome-Criteria fl)r inclusion and exclusion. Brain Dev 1985:7: 372-3. [121 Trevathan E, Moser ttW. Diagnostic criteria for Rett syndrome. Ann Neurol 1988:23:425-8. [131 Lekman A, Witt-Engerstrhm 1, Gottfries J, Percy AK, Svennerhold L, Hagberg BA. Rett syndrome: Biogenic amines and metabolites in postmortem brain. Pediatr Neurol 1989;5:357-62.
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114] Larsell O, Jan~n J, The comparative anatomy and histology of the cerebellunt: The human cerebellum, cerebel/ar connections and ccrebellar cortex. In: Larsell O. Janseu L cob,. Hunlan cerebellum, Minneapolis: University of Minnesota Pre,,+, b~72:3-64. 115] Papadimitriou JM, Hockey A. rf'illl N. ~ONtel*N('l-. P,cU syn drome: Abnormal membrane.-N~und lame!lined inclusions m neurom and oligodendroglia. Am J Med Geuet 1988:2'~: ~¢~5~, II61 Ghatak NR, Santoso RA. McKinnc5 WM. CeJ-ebellar degen eration following brag-term phenytom therap,,.. Nemoloev 1976;26 8 18-2O. [17] Vailarta JM, Bell DB. Rcichert ,-~ Buckle~ \V. Pmgressiw: encephalopathy due to chronic hydantom int<>xication. Am J [)is Child 1974:128:27-34. 1181 McLain l,W. Martin JT, Allen J l t ~, clebcllar degeucratkm due t~ chromic phenytoin therapy. Ann Neurol Ii;SO:7:l 8-23 119] Baler WK. Beck U, Doo~,e H, Klmgc 1t, Hirsch W. Ccrebell:ar atr~q~h~, follc,~+~,ing diphenylhydantoh~ h~l,~xmation. Neuropedialrie:, 1984:15:76-8 I. [201 Lindvall (), Nilsson B, Ccrebellar ;~mq)hy lollowiug phenylom mluxication, Ann Neurot 1984:16:2584~0. [21] Masnr l-t, Elger CE. Ludolph A ( , Galanski M (crebella~ atroph5 following actlle intoxication with phei+ut0in. Neurolog> lOg~) 39:432-3. [221 Southall I.)P. Kerl AM, l h t ! s h t+ .'\mOs P. [-al3g MH, Slephenson JBP. Hyperventilation in the awake state: Potentially treatable component of Rett syndrome. Arch Dis Child 1988;63:1039-481
The cerebellar pathology at autopsy of 5 patients with Rett syndrome is described. The patients ranged in age from 7-30 years. All had markedly reduced brain weights with proportionately small cerebella. Microscopic examination revealed loss of Purkinje cells, atrophy, astrocytic gliosis of the molecular and granular cell layers, and gliosis and loss of myelin in the white matter. Cortical atrophy occurred focally along the folia and was often more marked in the tips of the folia. The 2 oldest patients had been treated with phenytoin which may have contributed to the morphologic changes. Atrophy and gliosis increased with age or in patients without phenytoin treatment; the youngest patient demonstrated only minor microscopic changes. In addition to the generalized alterations, 1 patient had several adjacent folia with severe atrophy. The results indicate that cerebellar changes in Rett syndrome consist of general hypoplasia with the addition of atrophy beginning in childhood and progressing over many years.
patients and electroencephalograplL~. ~EEG) display,, a progressive pattern: however, smzures often subside with age [7]. Previous neumpathologic studies revealed micrencephaly [8,91. Microscopically, hypopigmentation of the substantia nigra has been described m most patients. In addition, the mconsistem occurrence of mild. diffuse cortical atrophy, mild gliosis, and mikl. Iocal ,',pongy aherations of the white matter has been reported [8,9]. In a recent study,, Oldfors et al. reported rnorphologic alterations in the spinal cord with astroc~ tic cellular and fibrillary gliosis and signs of degeneralion of both white and gray matter I lOf In spite of early incoordinatton in RS. pathologic findings of the cerebellum have not been described m detail. In our present study, we present the cerebellar pathology of 5 panents 17. t2. 17, 20, and 30 3ears of age) who fulfilled the diagnosnc crileria for RS I 1.12].
Case Reports
Rett syndrome (RS) is a globally distributed disorder with unknown etiology and pathogenesis which thus far is restricted to females [1-4]. The development during early infancy is normal. Even prior to a period of regression, which may last from 1 week to 1 year and features loss of interpersonal contact, acquired single words, and manipulative hand skills, several girls have displayed low muscle tone and poor equilibrium control [5]; however, regression ceases, leaving the child speechless, severely retarded, in an apraxic/dyspraxic state, and often with a characteristic jerky truncal tremor [2-5]. Interpersonal contact gradually improves while speech and hand skills never return. With increasing age, neurologic signs are characterized by the sequential appearance of spasticity, dystonia, rigidity, and weakness and wasting resulting in severe motor disability in most patients [3,4,6]. Epilepsy is present in 90% of the
('ascs S - i 2 . S 2 i . S-35. and (:$4~ h a , : been described previously [10.131. ('ase S-12 1'his patiem was born m 196(~ and died suddenly during a meal at the age of 20 years. Pre- and peri-natal histories were tmevent. ful. She was hypotonic and sat unsteadilx at S mnnths of a.,.z,e. C r a w l i n g never included reciprocal m o v e m e m s of the lower limbs Development phtteaued from 10-21 months of age (Stage I) 141. The regression period (Stage [ll occurred f r o m 13/a-21/'_ ,,x'ar', of age and included withd r a w n affecl and loss of standing, walking, and speech. At 30 m o n m s of age, her tone was decreased and equilibrmm funct nns mtpalred. Truncal ataxia d o m i n a t e d her ~mpalred m o l o r functions and handw r i n g i n g and dyspraxia or apraxia nterlered with her perl~rmance (Stage l i b From S years o f age. she was w h e e l c h a i r - b o u n d tStage lV). Seizures appeared al 22 months of age tot which p h e n y t o m was prescribed fi'om 5L/2-16 years. Plasnla concelrtlatRms on a lew occasions between 10-1 ~ years o f age exceeded the r e c o m m e n d e d Iherap~:utic level. From 13 years of a g e until her death at age 2~}. she was also treated with carbamazepine. {'a.xe S-21. "['his patient was born n 9~,7 and died suddenly o~ acute b r o n c h o p n e u m o n i a at 30 years of age Pre and peri-natal histories were uneventful. Early development v, as slovx and interpersonal contact never reached the intensity o f her siblings. Her best performance. at 7-20 months of a g e (Stage l was that or a 5 q 0 - m o n t h - o l d infant. At 30 m o n t h s of age, she progressed into Stage III and slowly regained s u p l x m e d walking in which limb and truncal ataxia ,aas ~hserved. Her p e r f o r m a n c e was apraxic. By t0 yea~s m age. she ,~as wheelchairhound, wasted, and dystonic (Stage IV~ AI 29 years ol a~ze. she was dystonic, rigid, and calm with a staring, unfathomable gaze. Seizures appeared at 101/2 years of age. Pheuvtoin (8-10 mg/kg) w a s prescribed l i n m 101/>lS years ol age; h o w e v e r fl-om I I years, she was raven 14
F r o m the Departments o f *Pathology a n d ~Pediatrics I1; University of G6teborg; G6teborg, Sweden; Departments of :~Pediatrics and *Pathology; B a y l o r College of Medicine; H o u s t o n , Texas.
C o m m u n i c a t i o n s should be addressed m Dr. Oldfors: D e p a r t m e n t o f Pathology; S a h l g r e n ' s Hospital. S-41345 G6teborg, Sweden. Received M a r c h 19. 1990: accepted Jul~ - 1~9().
OIdfors A, Sourander P, Armstrong DL, Percy AK, WittEngerstr6m I, Hagberg BA. Rett syndrome: Cerebellar pathology. Pediatr Neurol 1990;6:310-4.
Introduction
310
PEDIATRIC NEUROLOGY
Vol. 6 No. 5
A
B
Figure I. Seclioll.s' through the eerebellar hemi,v~heres" 0/ (At Patient S-21 and :B) Patient S-12 disclosed marked and /b~'al atrophy (arrow). A.B." original magni//cation. ,r2.3.
mg/kg liar I l/_~ years. Other antiepileptic drugs prescribed were pheno~ barbital, primidone, and carbamazepine. Case 5-35. This patient was born in 1977 and died in direct association with an operation for scoliosis at 12 years of age. Pre- and perinatal histories included a cesarean section ti)r placenta previa at 39 weeks gestation. Apgar scores were 9 at I min and 10 at 5 rain. Although she was slightly hypotonic, early development was within the normal range until 9 months of age when stagnation appeared (Stage 1). Her best achievements were in sitting, crawling, and standing, but she could not pull herself to a standing position. She had a pincer grasp, spokc l(I single words, and had good eye contact before regression (Stage IIL which occurred between I ~4-2~/2 years. At 15 months of age, she lost all motor skills, eye contact, and verbalization. Nine months later, she was hypotonic with jerky truncal ataxia: by 3(1 months of age, she was severely limited in all gross and fine motor functions (Stage IV). Deep tendon reflexes were brisk. At 12 years of age, she was severely motor disabled. Neurologic signs included prominenl lower neuron involvement, jerky truncal ataxia, some dyskinetic and dystonic trails, and hyperactive reflexes in the lower limbs. Contact and communication were somewhat improved. Fever-induced seizures occurred at IV4 years, mid epilepsy requiring antiepileptic drugs at 2!/4 years. Carbamazepine and valproate were administered, but not phenytoin. Case US-r~. This patient was born in I969 and died at age 17 years while hospitalized with severe pneumonitis which progressed into a puhnonary abscess, She was born at term and acquired normal milestones until the age of I year when she began head-banging and nailbiting (Stage 1). By age 2 years, her fingers were in continuous activity and her hands were clapping and flapping (Stage IlL Initial language development ceased and communication was lost. She was diagnosed as having infantile autism. By age 4 years, her walking was stiff" and uncoordinated and she fell frequently (Stage III). Independent walking stopped at 7 years of age (Stage IV). Three years later, she had her first generalized tonic-clonic seizure, received phenobarbital for some months, but had no antiepileptic drug therapy until age 14 years. At that point, she was severely motor-impaired with prominent dystonic rigidity but maintained eye contact and an occa-
sional social smile. Ethosuximide was administered with good clinical response. Ca.w US-36. This patient was born in 1982 and died suddenly at 7 years, 2 months of age. She exhibited normal early development for 14 months; however, in retrospect, she had hand and trunk tremors beginning at 12 months. Walking began at 14 months of age, but thereafter developmental progress ceased (Stage I). Between 18-24 months of age (Stage IlL she lost purposeful hand use and communication skills. Typical stereotypic hand-wringing and finger movements appeared. During Stage IlL bruxism (2V2 years), staring spells interpreted as seizures (3 years), and respiratory irregularity (apnea/hyperventilation) and scoliosis (4 years) were observed. EEG at age 3 years revealed multifocal spike-and-wave activity. Phenobarbital was administered but replaced in 1 month by carbamazepine which was withdrawn al age 5 years without apparent return of clinical seizures. During Stage llI, gait was progressively broad-based and apractic. Truncal ataxia increased and independent walking stopped at age 3 years. Her neurologic examination from this time until her death was marked by prominent hypotonia with normal deep tendon reflexes and no clonus. No evidence of dystonia or rigidity appeared.
Neuropathology of Cerebellum The autopsies were performed within 24 hours after death. All patients had severe muscular wasting and scoliosis. The brains were 25-35% smaller than normal and weighed 1,050 gm (S-12), 980 gm (S-21), 900 gm (S-35), 1,010 gm (US-36), and 920 gm (US-6). The cerebella were proportionally small. They were fixed with 4% paraformaldehyde and specimens were embedded in paraffin. For this study, sections from the vermis and both hemispheres of the cerebella were stained with silver impregnation (Palmgren), Luxol fast-blue-cresyl violet, and hematoxylin-van Gieson. Immunohistochemical staining
Oldfors et al: Cerebellum in Rett Syndrome
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of glial fibrillary acidic protein (GFAP, Dakopatts), fibronectin, and collagen IV (Labsystems) were performed with the avidin-biotin complex (ABC) method. Macroscopic Findings. Other than being small, the external surfaces of the cerebella exhibited no obvious morphologic changes. In case S-21, mid-sagittal sections through the vermis had very thin folia of all lobules. Case
312 PEDIATRICNEUROLOGY Vol.6 No. 5
Figure 2. Cerebeilar hemisphere o/'case S-2t. (A) Thin folia n'ith subtotal loss of Purkinje cells and reduction ¢~"white niatter. Lu.~ol fastblue-cresyl violet (LFBCV) stain, i(t3) Absence of Purkinje cells, marked/oss ~] granular cells, and a few remaining Go!gi ceUs. LFBCV stain, (C) Total loss c!( Purkiltje cells hut remaining parallel fibers~ and remtlants of haskets. Palmgren siA,er impregnation (PSI) stain. (D) Higher magnif~t'ation of Figure 2(71 PSI: stain: (E) Thin .f?~lia With marked gliosis qf both medulla and cortea. The g!iosis i~ especially abundant in the PurkiJlje cell layer, lrnmunohistochemicat stai~ ing of GFAP. (F Hi,~her magnification q[ Fi~4ure 2E revealing p 'oliferation of Bergmann glia and ~'adiating glial ~i': brils through the molecular cell layer. Inununohistochemical stainiag o[ GFAP, (G) Subtotal loss q]" axons in the White matter qf.fblia. PSI stain. (H) Astroc~to~Ls atM ghosis q( the white matter, bnmunohistoc'hemical staining of GFAP. Origina/ magn(f~eations: A,E: r40: B,D,F-H: x400: ( ' ~200.
S-12 had minor, generalized atrophy, tn the hemispheres, case S-21 had generalized but mild atrophy of the |otia; case S-12 had focal and marked atrophy corresponding to the inferior semilunar lobule [141 (Fig I)i Cases S-35, US-6, and US-36 had no visible atrophy. L i g h t M i c r o s c o p i c F i n d i n g S . Case S-21 had genea'atized atrophy with loss of Purkinje cells in a patchy distribution.
Several folia had complete loss of Purkinje cells (Figs 2A,2B). The molecular cell layer exhibited loss of nerve cells and gliosis. In some areas, stellate cells, parallel fibers, and basket Ion-nations remained in spite of the loss of Purkinje cells (Figs 2C,2D). Gliosis was marked with proliferation of the Bergmann glia and radiating glial projections through the molecular layer (Figs 2E,2F). The white maner appeared pale with myelin stain; in the atrophied folia, loss of axons was almost complete in some areas. Astrogliosis in the white matter was prominent, especially around blood vessels. The dentate nucleus had a reduced number of nerve cells and abundant astrogliosis. The immunohistochemical study using antibodies to albumin and fibronectin revealed no evidence of leakage of plasma proteins through vessel walls. In case S-12, the cortical and subcortical white maner changes in the hemispheric inlerior semilunar lobule were the same as in the most severely atrophied parts of the brain of case S-21. The remainder of the hemisphere and vermis had a milder degree of cortical atrophy which was often patchy in distribution, but affected the granular, Purkinje, and tnolecular cell layers. Atrophy was often more marked in the tips of the folia. The dentate nucleus was gliotic but there was no obvious loss of nerve cells. In case US-6, the folia were thinner than normal. There was patchy cortical atrophy and astrogliosis as in case S-12, but no folia with complete loss of Purkinje cells or severe atrophy we,'e observed. The white matter revealed loss of myelin, especially in the distal parts of the folia. The dentate nucleus demonstrated gliosis but no obvious loss of nerve cells. In case S-35, the tk)lia were generally thinner than normal. There was a moderate, generalized loss of Purkinje cells. As in the other patients, this change was locally accentuated and often seen in the tips of the folia. The atrophy was accompanied by proliferation of astrocytes with gliosis of all cortical cell layers. The gliosis was less conspicuous than in case US-6. in the bottom of 1 sulcus, there was complete absence of cortical cells in a sharply demarcated area revealing some gliosis. The white matter demonstrated loss of myelin, especially in the distal parts of the folia. The dentate nucleus revealed no changes. In case US-36, there was focally distributed loss of Purkinje cells and mild, focal gliosis of all cortical layers. The white tnatter had a minor degree of gliosis. The dentate nucleus appeared normal. Electron microscopic examination of cases S-12 and S-21 yielded no further inlbmmtion. No inclusions of the type described by Papadimitriou et al. were observed [ 15].
S- 12 displayed a large area of severe focal atrophy in the interior semilunar Iobule at age 20 years. In addition, a local loss or agenesis of a restricted part of the cerebellar cortex was observed in case S-35. The youngest patient (US-36, age 71/2 years) exhibited definite but minor atrophy. From these findings, it is concluded that the cerebellum in these RS patients exhibit both hypoplasia and atrophy. The pathogenesis of these changes is not clear. Early brain growth deficiency may be an essential part of the condition and the possibility of a lack of growth factors has been discussed I4]. Generalized cerebellar atrophy. especially loss of Purkinje cells, is a common finding in epileptic patients in whom it has been proposed that cell death may be due to hypoxia, possibly in combination with long-term overdosage of phenytoin [16-19I. Cerebellar atrophy has also been demonstrated on computed tomography (CT), following a few months of phenytoin treatment without overdose, epilepsy, or anoxia [20], and also after acute phenytoin intoxication [21 ]. The cerebellar changes, which have been reported in association with phenytoin medication, have a morphologic appearance similar to those in our patients 116-17]: however, in our series, only S-12 and S-21 were given phenytoin; the other patients received different antiepileptic drugs. Thus, the conclusion that the severity' of changes increase with age appears justified. In our patients, seizures were never observed before the first cerebellar signs; S-21 and US-6 had their first antiepileptic medication after 10 years of age. It is possible that hypoxia may have occuned during the typical alternating hyperventilation and breath-holding irregularities of RS [22]. However, no evidence of nerve cell death secondary to hypoxia in other parts of the brain, such as the hippocampus, was apparent in any of these 5 patients with RS. It appears that the cerebellar atrophy occurring in RS is not secondary to hypoxia or phenytoin medication, but is part of the primary disease. The multifaceted clinical picture in RS, which is already present in preschool age children, indicates widespread brain involvement. Some of the symptoms and signs in RS, such as the combination of early muscular hypotonia and dysequilibrium signs, are possibly clue to cerebellar dysfunction: however, their correlation, if any, with roof phologic changes is not proved.
This study was supported by the Swedish Medical Research Council (Project Number 07122), USPHS HD 24234, the S~.ivstaholm Association. tile Swedish Society for Medical Research. tile Sigurd and Elsa Golje Memorial Foundation. tile First of May Flower Annual Campaign for Children's Health, and the Jerring Foundation.
Discussion
Both the cerebrum and the cerebellum were considerably smaller than normal in all of our RS patients. Microscopically, the cerebellar abnormalities consisted of cortical atrophy and gliosis in a patchy distribution as well as loss of myelin and axons in the white matter. The degree of these alterations increased with age. Furthermore, case
References
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