- Email: [email protected]
“Inverse Chiari type II syndrome” in untreated hydrocephalus and its relationship to typical Arnold-Chiari syndrome
"Inverse Chiari Type II Syndrome" in U ntreated Hydrocephalus and Its Relationship to Typical Arnold-Chiari Syndrome Horst P Schmitt, MD Two cases of transtentorial upward displacement of the cerebellum in children with untreated hydrocephalus are reported. These cases clearly indicate that the condition is a primary malformation of the hindbrain and not a result of longstanding hydrocephalus treatment, as has been proposed in the past. The second case demonstrates the close relationship of the syndrome to classical Arnold-Chiari malformation. Schmitt HP. "Inverse Chiari type II syndrome" in untreated hydrocephalus and its relationship to typical Arnold-Chiari syndrome. Brain Dev 1981;3:271-5
"Transtentorial upward displacement of the cerebellum" has been considered to be a prima·ry malformation syndrome closely related to the Arnold-Chiari malformation [1, 2] rather than a result of hydrocephalus treatment or supratentorial decompression [3]. The term "inverse Chiari type II syndrome" has been proposed [1]. Since the first description by Daniel and Strich [4] in 1958 a total number of 23 cases has been reported in the literature [1] . To confirm further the concept of a primary malformation, observations of the occurrence of the syndrome in children without hydrocephalus From the Institute of Neuropathology, University of Heidelberg Medicial School, Heidelberg. Received for publication: January 16, 1981. Accepted for pUblication: April 3, 1981.
Key words: Malformation, cerebellum, trans tentorial displacemen t. Correspondence address: Prof. Dr. HP Schmitt, Institut fiir Neuropathologie, 1m Neuenheimer Feld 220, 6900 Heidelberg 1, West Germany.
drainage are of great importance. In addition, the close relationship with the Arnold-Chiari syndrome (i.e. Chiari's type II) can best be proved by demonstration of transitional forms between both. As relevant observations of this kind have been infrequent up to now, and the few reported ooes have not been adequately taken into account in the discussion of the nature of the upward-displacement syndrome, it seems worthwhile to describe briefly two cases. Case Reports
Case 1 This female child died at the age of 18 months due to a therapy-resistant epileptic status. She had been born after an uneventful full-term pregnancy and a prolonged difficult delivery. Since the first days of life she had suffered from recurring focal and later on generalized seizures. She did not exhibit signs of progressive hydrocephalus and no gross malformations. At autopsy (A-No. Ext. 278) coronal sections of
Fig 1 Case 1. a) Superior facies of the cerebellum and midbrain; upward displacement of the superior vermis and the anterior lobe (arrows indicate level of the tentorial rim); b) inferior facies of the cere· bellum and the brain stem. c) Posterior parts of the forebrain exhibiting a deep bowl·shaped impres· sion caused by the displaced cerebellar structures (bent arrows); d) coronal section at the parietal level showing moderate hydrocephalic dilation of the posterior horns of the lateral·ventricles.
the forebrain revealed a slight hydrocephalic dilatation of the ventricles, partially compensated by brain edema. The total brain weight (770 g) was below the normal age range, the cerebellum and the brain stem only weighing 110 g. The tentorium cere belli was hypoplastic with a low insertion and a flattened posterior fossa. Parts of the superior vermis and the lobuli quadrangulares protruded through the enlarged tentorial notch, leaving a bowl-shaped impression between the postero-basal parts of the cerebral hemispheres (Fig Ic). While the superior vermis exhibited an irregular configuration (Fig la), the inferior vermis was 272 Brain & Development, Vol 3, No 3,1981
markedly hypoplastic but otherwise regularly involuted (Fig 1b). There was no prominence of the tonsils. The histologic differentiation of the cerebellum was normal. However, in the cisterna pontis, dystopic glio-neuronal tissue with focal transitions into the pons tissue was found. The midbrain did not exhibit severe changes. It had a normal shape and histologic composition. The aqueduct had a somewhat irregular outline with many ependymal indentations. There was no aqueduct stenosis.
Case 2 This girl was born after an uncomplicated full-
Fig 2 Case 2. a, b) Cerebellum after reconstruction of the in situ relation between the tentorium and the anterior cerebellar facies: note the protrusion of the upper vermis and parts of the anterior lobe through the tentorial notch (arrow in b indicates the level of the foramen magnum).
tenn pregnancy and delivery. At birth she exhibited multiple severe malfonnations including a thoraco-Iumbar myelomeningocele with a dorsal and lateral partial rachischisis, severe scoliosis, thoracic situs inversus (dextrocardia) with a large left-sided diaphragmatic hernia containing abdominal viscera, hypoplasia of the left lung, left-sided fused kidneys with only one dilated ureter, anal atresia, and a divided (double) abdominal aorta. There was hypertelorism and a naevus flammeus covering the left side of the forehead and the upper lip, but no retinal nor meningeal angiomatosis. She died within 48 hours after birth. At autopsy (A-No 1065/79) the brain (total weight 480 g) exhibited severely dilated ventricles, multiple periventricular nodular heterotopias, protruding into the ventricular lumina, and polygyria due to multiple so-called gyral fusions with an increased number of incomplete gyral incisures. The full-blown tubular pattern of typical micro-
polygyria was not developed. The cerebellum was hypoplastic (weight 31 g) with a forebraincerebellum ratio of 14.5 (normal about 10 at birth). The tentorium was hypoplastic with a low insertion, parts of the superior vermis and the lobuli quadrangulares protruding through the enlarged tentorial notch (Fig 2a, b). The inferior vermis was irregularly shaped, incompletely involuted and parts of it were located within the foramen magnum. The medially extroverted choroid plexus protruded downward into the cervical spinal canal (Fig 2c). The pons was flattened; the fourth ventricle and the medulla oblongata were elongated, the latter showing a moderate kinking at its transition into the spinal. cord. Spur-like protrusions of the cerebellar hemispheres embraced the lower brain stem ventrally. The dentate nuclei and the inferior olives showed increased foldings (polymicrogyria), as did some minor parts of the cerebellar hemispheres. The upward disSchmitt: Inverse Chiari type II syndrome 273
i
c Fig 2 c) Microscopic median-sagittal section through cerebellum and brain stem (long arrows indicate the level of the foramen magnum): note the elongated rhomboid fossa and the stretched inferior vermis, which had protruded into the foramen together with the tips of the tonsils. The small arrow indicates the choroid plexus, which hang down into the spinal canal (mild form of the Arnold-Chiari malformation). d) Forebrain with bowl-shaped basal impression produced by the dip/aced cerebellar structures.
placed parts of the cerebellum had left a typical bowl-shaped impression in the forebrain basis (Fig 2d). Discussion The syndrome of trans tentorial cerebellar upward displacement is characterized by the following features: 1) Partial transtentorial protrusion of the cerebellum and the upper brain stem, 2) hypoplasia of the tentorium cerebelli with a low insertion and an enlarged notch, 3) elongation and flattening of the pons, the rhomboid fossa and the medulla oblongata (of varying degree), 4) frequent ventral embracement of the lower brain stem by spur-like extensions of the cerebellar hemispheres (may be absent), 5) hydrocephalus (of varying degree), and 6) spina bifida cystica (inconstant). 274 Brain & Development, Vol 3, No 3,1981
Case 1 is a typical example of the syndrome, which refutes the former hypothesis [3] that the condition is' the result of a longstanding supratentorial decompression due to hydrocephalus treatment. Five other similar observations have been mentioned in previous papers [4, 5], without putting special emphasis on their significance as to the interpretation of the pathogenesis of the condition. They clearly indicate that it has to be regarded as a primary malformation of the hindbrain. Case 2 combined typical features of the Arnold-Chiari malformation in addition to a moderate upward displacement. As the latter . has not been described by Chiari in his original monograph of 1896 [6], the phenomenon should not be included in the Arnold-Chiari malformation (Le. Chiari's type II) sensu strictiori. It is our belief that cases like case 2 represent
transitional forms between both syndromes, indicating their close relationship. A few similar cases have been described in former clinical papers without detailed anatomical delineation [4,5,7]. Hence it can be regarded as definitely settled that there exists in addition to classical ArnoldChiari malformation a second, closely related syndrome with a displacement of cerebellar structures in the opposite direction ("inverse Chiari type II syndrome"), both syndromes being linked by transitional forms.
4.
References 1. Schmitt HP. Syndrome of primary transtentorial cerebellar displacement - "inverse Chiari type II syndrome." Neuropaediatrie 1978;9:268-76. 2. Schmitt HP, Waidelich W, Harms E, Ule G. Partial transtentorial displacement of the cerebellum
7.
3.
5. 6.
and the brain stem in hydrocephalus - A primary condition or a result of treatment? Acta Neuro· chir (Wien) 1976;33:151-65. Emery JL. Intracranial effects of longstanding decompression of the brain in children with hydrocephalus and meningomyelocele. Dev Med Child NeuroI1965;7:302-9. Daniel PM, Strich SJ. Some observations on the congenital deformity of the central nervous system known as the Arnold-Chiari malformation. J Neuropathol Exp NeuroI1958;17:255-66. Peach B. Arnold-Chiari malformation. Arch Neu· roI1965;12:.!,13-21. Chiari H. Uber Veriinderungen des Kleinhirns, des Pons und der Medulla oblongata in Folge von congenitaler Hydrocephalie des Grosshirns. Denkschriften der kaiserlichen Akademie d'er Wissenschaften Wien, Mathematisch-naturwissenschaftliche Klasse, 1896:63. Sunder-Plassmann M, Salah S, Jellinger K. Late death in cases of internal hydrocephalus treated during early childhood. Neuropaediatrie 1975;6: 162-75.
Schmitt: Inverse Chiari type II syndrome 275
"Transtentorial upward displacement of the cerebellum" has been considered to be a prima·ry malformation syndrome closely related to the Arnold-Chiari malformation [1, 2] rather than a result of hydrocephalus treatment or supratentorial decompression [3]. The term "inverse Chiari type II syndrome" has been proposed [1]. Since the first description by Daniel and Strich [4] in 1958 a total number of 23 cases has been reported in the literature [1] . To confirm further the concept of a primary malformation, observations of the occurrence of the syndrome in children without hydrocephalus From the Institute of Neuropathology, University of Heidelberg Medicial School, Heidelberg. Received for publication: January 16, 1981. Accepted for pUblication: April 3, 1981.
Key words: Malformation, cerebellum, trans tentorial displacemen t. Correspondence address: Prof. Dr. HP Schmitt, Institut fiir Neuropathologie, 1m Neuenheimer Feld 220, 6900 Heidelberg 1, West Germany.
drainage are of great importance. In addition, the close relationship with the Arnold-Chiari syndrome (i.e. Chiari's type II) can best be proved by demonstration of transitional forms between both. As relevant observations of this kind have been infrequent up to now, and the few reported ooes have not been adequately taken into account in the discussion of the nature of the upward-displacement syndrome, it seems worthwhile to describe briefly two cases. Case Reports
Case 1 This female child died at the age of 18 months due to a therapy-resistant epileptic status. She had been born after an uneventful full-term pregnancy and a prolonged difficult delivery. Since the first days of life she had suffered from recurring focal and later on generalized seizures. She did not exhibit signs of progressive hydrocephalus and no gross malformations. At autopsy (A-No. Ext. 278) coronal sections of
Fig 1 Case 1. a) Superior facies of the cerebellum and midbrain; upward displacement of the superior vermis and the anterior lobe (arrows indicate level of the tentorial rim); b) inferior facies of the cere· bellum and the brain stem. c) Posterior parts of the forebrain exhibiting a deep bowl·shaped impres· sion caused by the displaced cerebellar structures (bent arrows); d) coronal section at the parietal level showing moderate hydrocephalic dilation of the posterior horns of the lateral·ventricles.
the forebrain revealed a slight hydrocephalic dilatation of the ventricles, partially compensated by brain edema. The total brain weight (770 g) was below the normal age range, the cerebellum and the brain stem only weighing 110 g. The tentorium cere belli was hypoplastic with a low insertion and a flattened posterior fossa. Parts of the superior vermis and the lobuli quadrangulares protruded through the enlarged tentorial notch, leaving a bowl-shaped impression between the postero-basal parts of the cerebral hemispheres (Fig Ic). While the superior vermis exhibited an irregular configuration (Fig la), the inferior vermis was 272 Brain & Development, Vol 3, No 3,1981
markedly hypoplastic but otherwise regularly involuted (Fig 1b). There was no prominence of the tonsils. The histologic differentiation of the cerebellum was normal. However, in the cisterna pontis, dystopic glio-neuronal tissue with focal transitions into the pons tissue was found. The midbrain did not exhibit severe changes. It had a normal shape and histologic composition. The aqueduct had a somewhat irregular outline with many ependymal indentations. There was no aqueduct stenosis.
Case 2 This girl was born after an uncomplicated full-
Fig 2 Case 2. a, b) Cerebellum after reconstruction of the in situ relation between the tentorium and the anterior cerebellar facies: note the protrusion of the upper vermis and parts of the anterior lobe through the tentorial notch (arrow in b indicates the level of the foramen magnum).
tenn pregnancy and delivery. At birth she exhibited multiple severe malfonnations including a thoraco-Iumbar myelomeningocele with a dorsal and lateral partial rachischisis, severe scoliosis, thoracic situs inversus (dextrocardia) with a large left-sided diaphragmatic hernia containing abdominal viscera, hypoplasia of the left lung, left-sided fused kidneys with only one dilated ureter, anal atresia, and a divided (double) abdominal aorta. There was hypertelorism and a naevus flammeus covering the left side of the forehead and the upper lip, but no retinal nor meningeal angiomatosis. She died within 48 hours after birth. At autopsy (A-No 1065/79) the brain (total weight 480 g) exhibited severely dilated ventricles, multiple periventricular nodular heterotopias, protruding into the ventricular lumina, and polygyria due to multiple so-called gyral fusions with an increased number of incomplete gyral incisures. The full-blown tubular pattern of typical micro-
polygyria was not developed. The cerebellum was hypoplastic (weight 31 g) with a forebraincerebellum ratio of 14.5 (normal about 10 at birth). The tentorium was hypoplastic with a low insertion, parts of the superior vermis and the lobuli quadrangulares protruding through the enlarged tentorial notch (Fig 2a, b). The inferior vermis was irregularly shaped, incompletely involuted and parts of it were located within the foramen magnum. The medially extroverted choroid plexus protruded downward into the cervical spinal canal (Fig 2c). The pons was flattened; the fourth ventricle and the medulla oblongata were elongated, the latter showing a moderate kinking at its transition into the spinal. cord. Spur-like protrusions of the cerebellar hemispheres embraced the lower brain stem ventrally. The dentate nuclei and the inferior olives showed increased foldings (polymicrogyria), as did some minor parts of the cerebellar hemispheres. The upward disSchmitt: Inverse Chiari type II syndrome 273
i
c Fig 2 c) Microscopic median-sagittal section through cerebellum and brain stem (long arrows indicate the level of the foramen magnum): note the elongated rhomboid fossa and the stretched inferior vermis, which had protruded into the foramen together with the tips of the tonsils. The small arrow indicates the choroid plexus, which hang down into the spinal canal (mild form of the Arnold-Chiari malformation). d) Forebrain with bowl-shaped basal impression produced by the dip/aced cerebellar structures.
placed parts of the cerebellum had left a typical bowl-shaped impression in the forebrain basis (Fig 2d). Discussion The syndrome of trans tentorial cerebellar upward displacement is characterized by the following features: 1) Partial transtentorial protrusion of the cerebellum and the upper brain stem, 2) hypoplasia of the tentorium cerebelli with a low insertion and an enlarged notch, 3) elongation and flattening of the pons, the rhomboid fossa and the medulla oblongata (of varying degree), 4) frequent ventral embracement of the lower brain stem by spur-like extensions of the cerebellar hemispheres (may be absent), 5) hydrocephalus (of varying degree), and 6) spina bifida cystica (inconstant). 274 Brain & Development, Vol 3, No 3,1981
Case 1 is a typical example of the syndrome, which refutes the former hypothesis [3] that the condition is' the result of a longstanding supratentorial decompression due to hydrocephalus treatment. Five other similar observations have been mentioned in previous papers [4, 5], without putting special emphasis on their significance as to the interpretation of the pathogenesis of the condition. They clearly indicate that it has to be regarded as a primary malformation of the hindbrain. Case 2 combined typical features of the Arnold-Chiari malformation in addition to a moderate upward displacement. As the latter . has not been described by Chiari in his original monograph of 1896 [6], the phenomenon should not be included in the Arnold-Chiari malformation (Le. Chiari's type II) sensu strictiori. It is our belief that cases like case 2 represent
transitional forms between both syndromes, indicating their close relationship. A few similar cases have been described in former clinical papers without detailed anatomical delineation [4,5,7]. Hence it can be regarded as definitely settled that there exists in addition to classical ArnoldChiari malformation a second, closely related syndrome with a displacement of cerebellar structures in the opposite direction ("inverse Chiari type II syndrome"), both syndromes being linked by transitional forms.
4.
References 1. Schmitt HP. Syndrome of primary transtentorial cerebellar displacement - "inverse Chiari type II syndrome." Neuropaediatrie 1978;9:268-76. 2. Schmitt HP, Waidelich W, Harms E, Ule G. Partial transtentorial displacement of the cerebellum
7.
3.
5. 6.
and the brain stem in hydrocephalus - A primary condition or a result of treatment? Acta Neuro· chir (Wien) 1976;33:151-65. Emery JL. Intracranial effects of longstanding decompression of the brain in children with hydrocephalus and meningomyelocele. Dev Med Child NeuroI1965;7:302-9. Daniel PM, Strich SJ. Some observations on the congenital deformity of the central nervous system known as the Arnold-Chiari malformation. J Neuropathol Exp NeuroI1958;17:255-66. Peach B. Arnold-Chiari malformation. Arch Neu· roI1965;12:.!,13-21. Chiari H. Uber Veriinderungen des Kleinhirns, des Pons und der Medulla oblongata in Folge von congenitaler Hydrocephalie des Grosshirns. Denkschriften der kaiserlichen Akademie d'er Wissenschaften Wien, Mathematisch-naturwissenschaftliche Klasse, 1896:63. Sunder-Plassmann M, Salah S, Jellinger K. Late death in cases of internal hydrocephalus treated during early childhood. Neuropaediatrie 1975;6: 162-75.
Schmitt: Inverse Chiari type II syndrome 275