Principles of Neurosurgery, edited by Robert G. Grasonan Rsacsberf *; FWt. Published bv Raven Press, LaL, Nc* Voft.

CHAPTER 2 l Skul e th f o s Disease y Primar

John P. Laurent

Granulomatous, 21 Vascular, 22 Histiocytosis X, 21 Hemangioma, 22 Osseous, 21 Aneurysmal Bone , 22 Fibrous Dysplasia, 21 Neoplastic, 22 Orbital Dysplasia, 21 Sarcoma, 22 Osteoma, 22 Chondroma, 22 Ossifying Fibroma, 22 Chordoma, 22 Osteoid Fibroma, 22 References, 23

GRANULOMATOUS OSSEOUS

Histiocytosis X Fibrous Dysplasia Fibrous dysplasia is a common bony mesenchymal Histiocytosis X is a group of three reticuloendothelial lesion of both the skeleton and cranial vault with onset in diseases involving bone (1). Eosinophilic granuloma, the childhood or adolescence. Progression of the lesions oc- most common, usually appears as a single lesion in the curs during periods of skeletal growth, later followed by n lesio e Th . age f o s year n seve o t r fou d chil a f o l skul ossification. The monostotic form involves a single causes localized pain, erythema, and swelling, and it may bone, and the polystotic form involves multiple bones. - dem l wil s Radiograph . l loca a h wit d confuse e b Albright's disease is a variation of polystotic fibrous dys- onstrate a lytic lesion with a punched-out, nonsclerotic plasia and manifests extraskeletally in the form of skin border. Excisional biopsy is recommended and curative pigmentations, sexual precocity, and endocrine dysfunc- of a single lesion. When the diagnosis is confirmed and tion (2). The histologic picture is distinctive, with dys- multiple bony lesions are present, low-dose radiation plastic bone in abundant collagen. Neurologic symp- (400 to 600 rads) will effectively eradicate the remaining toms are related to neural compression and foraminal lesions. entrapment, and they primarily involve the orbital, pe- Visceral reticuloendothelial involvement and numer- trosal, and sellar areas. ous calvarial lesions in an infant are called Letterer-Siwe Radiographs demonstrate areas of hyperostosis with disease. The prognosis is poor with extensive visceral in- mixed lucent and sclerotic margins. Three-dimensional volvement. computerized tomography (CT) is extremely helpful Han-Schuller-Christian disease is characterized by re- prior to surgical excision. Because hormonal, medical, ticuloendothelial involvement at the skull base and hypo- and radiation treatments have been unsuccessful, total thalamus in the older child. Symptoms may include dia- en-bloc resection of the dysplastic area causing neural betes insipidus, dwarfism, exophthalmos, and multiple compression should be attempted. Sarcomatous degen- skin lesions. The prognosis depends on the extent of eration can occur following radiation treatment. non-neural involvement but appears better than in Let- terer-Siwe disease. Orbital Dysplasia

J. P. Laurent: Section of Pediatric Neurosurgery, Baylor Col- Unilateral absence of the greater wing of the sphenoid lege of Medicine, Houston, Texas 77030. (orbital dysplasia) is diagnostic of von Recklinghausen's 21 22 / CHAPTER 2 t orbi e th o int e lob l tempora e th f o e Prolaps . disease t Cys e Bon l Aneurysma causes severe exophthalmos. Plexiform neurofibroma of the ciliary nerve and exophytic optic glioma should be Jaffe and Lichtenstein described an aneurysmal bone - win e bon l three-dimensiona A . considered y differentiall cyst in 1942 as a benign cystic bone lesion (3). Although dow CT scan is exceptionally helpful in planning surgi- aneurysmal bone rarely involve the skull, they have cal reconstructios area l n oftempora th d e an sphenoi , dparietal wing, . Enophthalmofrontal e th n i d sfoun n bee is a postreconstruction complication. (4). The origin of this tumor remains unknown. The rap- , characteristic s demonstrate s mas r tende , enlarging y idl Osteom- a roent l Skul . features c radiologi , diagnostic t no h thoug genograms may show a lesion with a typical soap-bubble appearance involving both tables and occasionally ex- An osteoma is a benign bone tumor, more common in panding intracranially. Angiography will clarify the vas- adults than in children, that arises from the outer diploe cular etiology. A CT scan will reveal an enhancing le- of the skull. Lesions are frequently found in the nasal or a h wit d line e ar s channel e bon e th , Histologically . sion mastoid sinuses. Skull osteomas are hard, painless - pol c coloni d an , tumors e tissu t sof , Osteomas . masses , formation e bon w ne d an , endothelium f o r laye e singl giant cells, and hemosiderin-laden histiocytes are evi- yposis form a triad of symptoms known as Gardner's syndrome- . Radiographrecom s i d an e s of osteomacurativ s i l s appearemova l r as thickenesurgica c dEn-blo . dent mended to decrease the possibility of posttraumatic hem- bone with variable lucency. Proptosis, sinus obstruction, orrhage. and cosmetic deformity are the primary indications for complete surgical removal of these tumors. NEOPLASTIC Ossifying Fibroma Sarcoma - dyspla s fibrou h bot o t r simila e ar s fibroma g Ossifyin sia and osteomas in histologic appearance. The clinical Sarcomas of the skull are extremely rare. They may be presentatio- me ne dependinvasiv l s on the primarextracrania r o c y locationintradiploi ,h whicwit d h confuse ningioma on presentation. The rapid increase in size of . sinuses y maxillar e th n i r o r mandibula r eithe e b l wil e caus y ma n compressio l neura l loca d an n Distortio . diagnosis l differentia e th n i s aid s lesion s sarcomatou , radiation, and chemotherapy postpone the even-^ r appea s fibroma g ossifyin , Radiographically . symptoms tual fatal outcome. - ar c scleroti h wit e bon d thin-shelle , well-demarcated s a e thes e becaus y mandator s i n excisio l surgica l Tota . eas lesions may recur locally and malignant changes may take place. Chondroma - histologi e th s a d regarde s i a chondrom c Synchondroti Osteoid Fibroma cally benign version of chordoma and commonly occurs at the skull base arising from junctional synostotic areas. Osteoi. d fibromsinuses l a tumorparanasa s e arth e rarm e fro an s d arearise seldoa m seenchondrom l Nasa in the skull. Severe local pain differentiates an osteoid Symptomatology depends on location. Although progres- - simi a e hav l wil h whic , cyst d epidermoi n a m fro a fibrom . occur n ca n degeneratio t malignan , slow y usuall s i n sio lar appearance radiologically (see Chapter 8). Treatment In Ollier's disease, other skeletal areas are involved in the of this tumor requires en-bloc resection. chondromatosis. Slow invasion and compression of neural structures produce significant neurologic symp- toms. Because the tumor is radiation-resistant and recur- VASCULAR - slow , benign s thi , common s i s site e operativ t a e renc growing tumor is often fatal. Hemangioma m seldo e ar , rare e ar t vaul l crania e th f o s Hemangioma Chordoma symptomatic, and commonly cause cosmetic concern. e th e whil d outwar d expan y the , diploe e th n i g Originatin Thought to derive from notochordal elements, chor- s i y etiolog e Th . intact n remai e tabl r inne d an m periosteu domas are aggressive tumors that arise at the cranial - lu s a r appea s hemangioma , Radiographically . unknown - to g expandin d an a sell d an s clivu e th g destroyin , base cent, honeycombed bone with nonsclerotic margins. Ex- ward the nasopharynx to compress the brain stem. Al- - ther n radiatio e becaus d recommende s i y biops l cisiona - intra e ar n childre n i s chordoma f o y majorit e th h thoug apy is unsuccessfuls adult n i n . regio l sacra e th n i r occu y usuall y the , cranial PRIMARY DISEASES OF THE SKULL / 23 s i a diplopi , intracranially d locate s i r tumo e th n Whe . (5) REFERENCES the most common complaint, followed by cranial nerve n brai e th f o n compressio r tumo o t e du n dysfunctio y McKa , NC n Vaugha : In . syndromes s histiocytosi e Th . AC r Crocke . 1 , lungs e th o t y usuall , metastasize y ma r tumo e Th . stem . edition h 11t Pediatrics, of Textbook Nelson . eds , RE n Behrma , JR . outcome l fata l eventua h wit . 1983 ; 1979 , Saunders B W , Philadelphia Chordomay b d s occasionallcharacterize e y shoSyndrom . w AO fine n , stippleHampto , d AM calcificatio r Butle , F t n Albrigh . 2 e endocrin d an n pigmentatio f o a are , disseminata s fibrose s osteiti on plain skull radiographs. Magnetic resonance imaging dysfunction with precocious puberty in females. N Engl J Med (MRI) is particularly useful in localizing the tumor. 1937;216:727-730. Radical surgical decompression of the clival tentorial 3. Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with empha- sis on roentgen picture, pathologic appearance and the pathogene- - treat y primar e th s a e effectiv s i t bu e curativ t no s i a are . 1942;44:1004-1025 Surg Arch . sis - sur m Long-ter . useful e b y ma y therap n Radiatio . ment 4. Cataltepe O, Inci S, Ozcan OE, Saglam S, Erbengi A. Aneurysmal vival in children. is possibl-394 1 e althoug1990;33:39 hNeural the Surg averag . bone l e survivafronta e th f lo t cys e bon time is four to seven years. Chordomas should not be 5. Wold LE, Laws ER. Cranial chordomas in children and young confused with synchondrotic chondroma. s of th1983;58:602-606 e same Neurosurg J . adults - chordo f o t treatmen l Surgica . LW r Ducke , 1C y Bail , MA r Faulrone . 6 - noto e th f o t varian n benig e th e ar s Chondroma . area - 1968;29:261 Neurosurg J . base l skul e th f o s chondroma d an s ma . (6) e angl l chorda 265. Principles of Neurosurgery, edited by Robert G. Grossman. Rosenberg © 1991. . York w Ne , Ltd. , Press n Rave y b d Publishe

CHAPTER 3 l Developmenta d an l Congenita Cranial Abnormalities k Chee . R m Willia d an t Lauren . P n Joh

Closure Defects of the Neuroepithelial , 25 Congenital Intracranial Tumors, 31 5 2 , Defects p Scal Hamartomas, 31 5 2 , Defects l Skul Teratomas, 32 Cephaloceles, 26 , 32 Dermal Sinus l Tracts, 27Congenita r o l Developmenta s Miscellaneou Epidermoids and Dermoids, 28 Abnormalities, 32 9 2 , Cysts l Intracrania l Congenita Phakomatosis, 32 9 2 , Cysts l Developmenta 2 3 , Pericranii s Sinu 0 3 , Cysts d Colloi References, 33

CLOSUR- E DEFECTcongeni , scalp e Sth o Ot a F THtraum E c obstetri e ar n ski f o e absenc NEUROEPITHELIA. tissue n brai c L ECTODERectopi d an , M l smal , lues l ta Most of the defects, even those up to 10 cm, heal sponta- s Defect p Scal - threat e lif e b y ma s sinu l sagitta e th r ove s Defect . neously ening, however, and an early full-thickness skin graft , congenita s cuti a aplasi r o , scalp e th f o s ulcer l Congenita - neo n i r dange f o d perio t greates e Th . necessary e b y ma may occur in the newborn without the presence of other nates extends from birth to eight days. Many defects do intracranial abnormalities. Most such defects are located not heal completely and require surgical repair. If dura is . multiple e b y ma d an , size n i y var , area l parieta e th n i s i t graf e pedicl n ski s full-thicknes a , defect e th t a d expose - ex y ma t defec e th f o e bas e th , absent s i l skul e th n Whe needed; otherwise, split-thickness grafts can be made. tend to the subarachnoi. dnecessary spacem . Aseldo s parchment-likei t defec y bon e , moisth f o te Closur membrane covers the area, but there is no underlying supporting structure. Skull Defects o t d postulate n bee s ha n lesio e th f o s pathogenesi e Th be pressuree necrosith f o e s durinclosur e g laborcomplet , t amniotipreven cn adhesionca s defect s l Fusiona with tearino als gs i op f thescal skine th f ,I arres. t occur o fn midlinca s e developmentdefect n ,Ossificatio . skull or defective neural tube closure. Incomplete fusion of absent, the prognosis is worse, and surgical repair and the mesoderm, along with localized arrest of ectodermal skin grafting are needed to prevent hemorrhage or infec- - occip e midlin A . theory l logica t mos e th s i , development tion. Cranioplasty, if indicated, should not be done until , arhinencephalia , . typical s i n locatio l ita the child is three or four years old. d associate y commonl t mos e th e ar s defect e midlin d an The most common congenital defect is bilateral pari- congenital abnormalities. etal foramina located at the parietal emissary veins. l congenita h wit d confuse e b y ma t tha s lesion r Othe e routin n i s discoverie l incidenta e ar s defect h suc y Man d bevele a y b d surrounde s i t defec e Th . radiographs l skul nonsclerotic rim of bone and is filled with fibrous tissue. J. P. Laurent and W. R. Cheek: Section of Pediatric Neuro- This defect is not clinically important, and cranioplasty . 77030 s Texa , Houston , Medicine f o e Colleg r Baylo , surgery is seldom indicated (Fig. 1). 25 26 / CHAPTER3 tissue failure at ossification sites of the cranial vault. Cleidocranial defects are predominantly midline defects, l crania e th f o e failur d an s t absen f o g consistin - particu , involvement c Mosai . normally e clos o t s suture - osteogene f o c characteristi s i , bones l parieta e th f o y larl sis imperfecta. Neurosurgical intervention is not indi- . abnormalities l skul l mesenchyma e thes r fo d cate

Cephaloceles

A congenital cephalocele is an extracranial protrusion of the leptomeninges, with or without cerebral tissue, e ar s Meningocele . bones l crania e th n i t defec a h throug protrusions without brain tissue; encephaloceles contain brain. The most common location of cephaloceles in pa- tients of European or American ancestry is occipital, with a frequency of less than 1 in 1,000 live births. The incidence is higher in patients of Southeast Asian extrac- tion, in whom the lesions more commonly occur in the frontal ethmoidal area. The embryologic events leading to the disorder are unknown. The most widely accepted FIG. 1.f o Congenita k lac , l bilaterastage c l parietaembryoni l e foraminth g a seedurin t n otha n s a skulhold ly theor radiograph. separation of the brain, dura, and skin results in a defect e th f o n herniatio t subsequen h wit t vaul l crania e th n i In childree th n i nd with locate pulsatin s g exophthalmocephalocele f o n origi se anTh . d protru- leptomeninges c neurologi r othe o n w sho o wh e bon l tempora e th f o n sio basilar region has been attributed to faulty ossification d sphenoi e th f o t defec l congenita a , symptoms r o s sign centers. A cephalocele is usually diagnosed at birth. Dif- - asso y frequentl s i r disorde s Thi . present e b y ma e bon - malfor r vascula , teratoma , dermoid a m fro n ferentiatio ciated e witth , h neurofibromatosiscases t mos n I . . Idifficult n e mosb y t ma children a , hygrom earl r o y, mation complaints can be related to exophthalmos. Agenesis of pathologic factor causing the lesion can be determined h Althoug . bulging l tempora s cause e bon d sphenoi e th by computerized axial tomography (CT), magnetic reso- o t s cease l skul e th r afte s progres t no s doe s exophthalmo nance imaging (MRI) of the head, or both. Unilateral - be y ma y deformit e th t correc o t y surger c cosmeti , grow exophthalmos can be caused by a cephalocele. . necessary e com . pedunculated r o d broad-base e b y ma s Cephalocele Epicranial arachnoid cysts and ectopic glial tissue oc- Epithelium may completely cover the sac, or some areas casionally appear as masses at the obelion, and in most may be partially transparent. The size of the mass does patients an underlying skull defect is present. A fibrous not determine whether brain tissue is present. Clinical e b y ma s element d dermoi d an , dura e th o t s extend k stal - sincipi , parietal , occipital e ar n locatio y b s classification y necessar s i s lesion e thes f o l remova l Surgica . present tal, basal, nasal, and orbital. Occipital cephaloceles are . problem e th t correc y usuall l wil d an not difficult to diagnose, compared with the difficulties "Craniolacunia," "Luckenschadel," and "beaten encountered in diagnosing nasal ethmoidal, nasal or- silver" n are termchildre n sI use. 2) d. to (Fig describ s e a characteristicephalocele l fronta l c radionasa d -an , bital l crania e th f o g thinnin y patch h wit e appearanc c logi a , contemplated s i p poly l nasa a f o y biops a m who n i - nor h wit d confuse n ofte s i , newborn e th n i , which , vault cephalocele needs to be considered (Fig. 3). Skull films mal convolutional markings. Lacunar skull is com- are unreliable in diagnosing basilar and frontal cephalo- monly , associated (horizontal wit s h myelomeningocelescan I MR d an T C h s anWit d. encephinfants -n i s cele alocelese . th Therd an d e is nodelineate e correlatiob n ca s nmas e betweeth , n craniocoronal) d an , - sagittal lacuni. a and hydrocephaludetermined t s or involvemen increase e tissu d l intracraniacerebra f o lt exten s i d an a are l parieta e th n i s occur l skul r Lacuna . pressure - encephalo l occipita m fro t involvemen e ventricl h Fourt caused. b(1) y ay mesenchymasurger o t r prio l I developmentaMR m fro d l disturbancidentifie e b n e ca s cele with delayed ossifications. Reestablishment of normal Testing for visual evoked responses (VERs) in children l norma a d an , birth r afte y shortl s begin n ossificatio e bon g ascertainin n i l helpfu s i s cephalocele l occipita h wit . age f o s month e thre y b n see e b n ca n patter l skul whether cerebral tissue is present in the sac, but it does a imperfect s osteogenesi d an s dysostosi l Cleidocrania - ab e Th . tissue e th f o y capacit l functiona e th l revea t no are the result of a generalized mesenchymal connective sence of VERs is of no diagnostic importance. CONGENITAL AND DEVELOPMENTAL CRANIAL ABNORMALITIES / 27

. l occipita e Larg . 2 . FIG

When (CSF) is leaking or the skin these areas may involve only the "silent" areas of the is extremel- yhypo e transparentth f o s , surgerstructure l yvita shoule d involv b ey donma r eo earlye lob .l fronta - im o t t no , mass e th e remov o t e don s i n operatio e Th thalamus. l smal f o t treatmen l Surgica . status c neurologi e th e prov s i n erosio n ski d an , leakage F CS , infection f o k ris e Th occipital lesions is not formidable, and mortality is mini- increased in patients in whom the lesion is not repaired. - cephalo l occipita h wit s patient r fo s prognosi e Th . mal d displace e tissu l cerebra f o t amoun e th n o s depend s cele extracranially. Brain tissue in the encephalocels e Tract i ss invariSinu l - Derma ably dysgenetic. Hydrocephalus, which occurs in 50 per- - abnormali n brai d associate d an , patients e thes f o t cen Dermal sinus tracts are tubes of stratified squamous e th e increas , present y commonl o als e ar h whic , ties l lumbosacra e th n i d locate e ar h whic f o t mos , epithelium - defi c neurologi l menta d an r moto h bot t tha y probabilit l crania f o s case 6 4 d reporte o Curatol d an e Giuffro . area . develop l wil s cit - devel s symptom d an s sign , majority e th n i ; sinus l derma Anterior malformations (nasal frontal, frontal orbital, oped before four years of age (2). A midoccipital location - oc n tha t trea o t t difficul e mor e ar ) ethmoidal l nasa d an predominated (85 percent) (Fig. 4). Cheek and Laurent cipital lesions, and multiple surgical procedures are reported the largest series of patients with congenital na- - im s i a dur e th f o e closur l Intracrania . required y usuall sal dermal sinus (3). n i e encephalocel n A . leakage F CS t preven o t t portan Congenital dermal sinus tracts develop in the third to - separa e incomplet f o t resul a s a n gestatio f o k wee h fift . ectoderm l epithelia e th m fro m neuroectoder e th f o n tio These tracts can extend to any depth into the neural tissue, depending on the stage at which incomplete dif- e tub l neura e th f o e closur e Becaus . occurred n ferentiatio d cauda h bot n i s extend d an n regio l cervica e th n i s begin and cephalad directions, the possibility of incomplete cleavage is greatest in the caudal direction. The tracts will extend cephalad when located over the spinal area - protuber l occipita e th e abov d locate n whe d cauda d an e th d towar y posteriorl t projec s tract s sinu l Nasa . ance crista galli. Because of their embryonic origin, a midline . characteristic s i n locatio e near-midlin r o - exter e th e abov e originat s tract s sinu l crania r Posterio nal occipital protuberance, and nasal sinus tracts origi- nate predominantly at the distal third of the nose (Fig. 5). - nasal e th h throug g projectin s encephalocele l Nasa . 3 . FIG Both of these lesions may extend into the scalp, the skull, frontal bone junction should be differentiated from dermoids the extradural space, or the intradural space. Expansions . gliomas c ectopi d an . tract e th f o e cours e th g alon r o s terminu e th t a r occu n ca 28 CHAPTERS the entrance to the sinus tract. The patient may have recurrent episodes of Staphylococcus aureus . s mas a f o e presenc e th t sugges t tha r occu y ma s Symptom in the posterior fossa, or a cerebral . Leakage of - menin c asepti e caus y ma d dermoi e th m fro l materia gitis. A smooth, rounded midline defect and grooving of the calvarium in the may be seen in radio- graphs. Nasal sinus tracts with an intracranial extension are frequently associated with a wide or bifid crista galli on frontal polytomographic radiographs. A CT or a MRI scan may show a mass, bony abnormalities, or a cyst t significan o n y usuall s i e Ther . displacement n brai h wit enhancement. o t y secondar s adhesion e befor e don e b d shoul y Surger l tota f o s consist t treatmen e Th . develop n ca s meningiti - ex l intracrania y an g includin , tract s sinu e th f o n excisio tensions.

Epidermoids and Dermoids

Epidermoids comprise 1 percent of cerebral neo- FIG. 4. Posterior dermal sinus tracts commonly pierce the plasms, and dermoids not related to a sinus tract com- r posterio e th o int y caudall k trac d an a torcul e th e abov n ski prise a lower percentage. Both lesions are believed to be fossa. inclusion cysts of epithelial cells that develop during clo- sure of the neural tube in the third to fifth week of gesta- t a e becaus , dermoids d considere e ar s expansion e Thes tion. A predilection for a midline location supports this least twc o germinaopti f o e l celclosur l g layerdurin s cas ncell bt e seeres f o n t on histologiEntrapmen c. theory examination. and otic vesicles may explain the developmental lesions A dimple, often with protruding hairs and a port wine in these areas. t a n ski e th n o t presen e b l wil , skin e th f o n discoloratio n i " pearles r "tumou m ter e th f o e us s Cruveilhier' r late t tha s lesion e th f o n descriptio l classica a s wa 9 182 became known as epidermoids. The cysts are composed of a stratified squamous epithelial lining and expand in- f o t conten e Th . debris n kerati f o n exfoliatio y b y ternall an epidermoid is more fluid than that of a dermoid. Ex- e th d an e fontanell r anterio e th n i r occu s lesion l tracrania s lesion l Intracrania . 6) . (Fig e diplo l parieta d an l fronta e cerebellopontin e Th . located y paramediall e b o t d ten e th e ar s ventricle e th d an , area y parapituitar e th , angle major locations of epidermoids, in order of descending frequency. Dermoid cysts are composed of hair follicles, sweat, and sebaceous glands, in addition to squamous epithe- lium, and become enlarged owing to deposition of kera- tin debris, hair, and material from the sebaceous cysts. Thus, the contents of these cysts have a "cheesy" consis- tency. Common extracranial locations of dermoid cysts are the anterior temporal area, the supraorbital diploe, the bridge of the nose, and the occipital region. When it e hav y ma t cys e th , occipitally r o e nos e th t a d locate s i eroded through the inner table and expanded extradur- h fourt e th n i r occu y usuall s dermoid l Intracrania . ally - ante e th t a n ski e th e pierc s tract s sinu l derma l Nasa . 5 . FIG rior third of the nose and track under the nasal bones to the ventricle, the posterior fossa, the vermis, or the region at falx cerebri. . skull e th f o e bas e th CONGENITAL AND DEVELOPMENTAL CRANIAL ABNORMALITIES / 29 graphs. Lesions in the calvarium can usually be diag- nosed by routine skull radiographs and are seen as sharply marginated, lucent defects with sclerotic edges. - Ero . present y occasionall s i t enlargemen c Intradiploi - ero e tabl r inne t bu , common s i e tabl r oute e th f o n sio d an s epidermoid l intradura h Bot . 7) . (Fig e rar s i n sio l revea l wil y Angiograph . calcified e becom y ma s dermoid e displac o t h enoug e larg s i n lesio e th f i s mas r avascula n a . diagnosis e th g establishin n i l helpfu s i n sca T C A . vessels These lesions commonly appear as low-density masses, and no enhancement has been reported. - epider d an s dermoid l extracrania r fo t treatmen e Th moids is complete excision; for skull lesions the bone - Intra . cure e complet a e achiev o t d curette e b t mus s edge cranial lesions are more difficult to treat, depending e th s i n resectio e Complet . location d an e siz r thei n upo - con l wil s cell l epithelia g remainin y An . therapy f o m ai tinue to keratinize and desquamate, and the mass will recur. Spillage of the cystic material at operation can s dose h hig t bu , reaction l meningea c asepti e sever a e caus . risk s thi e minimiz l wil s steroid f o FIG. 6. Common location of an epidermoid cyst is at sutural junctions. CONGENITAL INTRACRANIAL CYSTS Palpable epidermoid or dermoid cysts are nontender, , present f i , Tenderness . firm d an , immobile y relativel s Cyst l Developmenta e differenc e Th . infection r o a traum f o t resul a e b y ma between dermois ha s d ancyst l d epidermoiintracrania c d cysts is histologicalnonneoplasti f o y .variet e wid A - radio n i s change e sam e th e produc y ma s type h Bot - patho d an y etiolog e th , literature e th n i d describe n bee genesis of which are controversial. The classification sys- f o e usag n commo t bu , unjustified s i s cyst e thes r fo m te certain terms has prevailed (4). Arachnoid cysts can occur anywhere in the cranial vault. The most common supratentorial site is the syl- vian area or middle fossa. Other locations are the parasa- gittal area, the convexity, and the posterior fossa (Fig. 8). The abnormal development of the perimedullary mesh, with collections of fluid between the arachnoid leaves, may cause these cysts to develop, or a dysgenetic portion n malformatio d arachnoi n a e caus y ma n brai e th f o - ei f o s cyst f o t treatmen e Th . fluid h wit s fill n the h whic . same e th s i n origi r the The wall of an arachnoid cyst is smooth, with no evi- - epi y secretor o N . hemorrhage r o n inflammatio f o e denc thelium can be seen on microscopic examination. Brain tissue adjacent to the cyst may be normal, gliotic, or n whe n commo e ar g bulgin d an n erosio y Bon . dysgenetic the cyst is located in the temporal fossa. The cysts are d flui e th y occasionall t bu , fluid r clea h wit d fille y usuall will be xanthochromic and will have a high protein con- - cis l basa e th h wit e communicat y freel s cyst e Som . tent g makin , fossa l tempora e th n i e thos y particularl , tern " "cysts. e tru n tha r rathe e diverticula m the n i r manne e th s determine t cys e th f o n locatio e Th FIG. 7. l Anwil anterios rinfant fontanelln i s elesion dermoil d seen oSupratentoria n. a coronamanifest l s Ci Tt i h whic scan. cause megacephaly or signs of increased intracranial 30 / CHAPTERS

FIG. 8. Surgical view of a posterior fossa arach- noid cyst that was diagnosed in utero.

pressure. The head will be asymmetrical, and focal nedro- Ependymal cysts do not develop in the ventricular sys- y ma t cys l infratentoria n A . present e b y ma s sign c logi tem or the subarachnoid space but presumably originate y b d cause e thos o t r simila s symptom d an s sign e produc s resemble g linin r Thei . cells l ependyma d displace m fro h bot f o e cours l clinica e Th . fossa r posterio e th f o s tumor y probabl d an a ependym l norma e th f o s cell d ciliate e th supratentoria- l anhyperosmo d s infratentoriai d flui e Th . l cysts iscapability prolongedy secretor ,a uns - maintain less bleeding into the cyst should occur. lar and has a high protein content. Ependymal cysts The natural history of arachnoid cysts varies. MRI manifest signs and symptoms resembling those of a scans ine sagittamad y l and axiacommonl l s planei s s are helpfuDiagnosi . l lesion i ng planning space-occupyin n resectio , shunts l Cyst-peritonea . approach l surgica e th by CT or MRI scanning. Bony erosion is uncommon. A r o e ventricl e th o int t cys e th f o g openin d an , wall t cys f o cure is effected by excising the cyst wall. the basilar cisterns are the most commonly used surgical A porencephalic cyst is a cavity communicating with treatments- . occlu r vascula t anteceden n A . system r ventricula e th sion is the most likely origin. It is possible to diagnose many of these lesions in asymptomatic patients with CT - in n i s puncture r ventricula e Multipl . scanning I MR r o e thes e caus y ma s hydrocephalu e high-pressur h wit s fant "cysts" to develop. If the is associated with hydrocephalus, a shunt will be necessary. Differentiation between "true" cysts and porencephalic cysts may be - deter l wil s change l pathologica g underlyin e Th . difficult mine the prognosis (Fig. 9).

s Cyst d Colloi

"Colloid cyst," "paraphyseal cyst," "neuroepithelial cyst," and "cyst of the foramen of Monro" are the t a g originatin n lesio s thi e describ o t d use s term s variou the median or paramedian embryonic structure from which the roof of the third ventricle develops (Fig. 10). - di s i t cys e th f o l wal r oute e th f o e surfac e th h Althoug rected into the third ventricle, no cilia are located on this FIG. 9. Skull radiograph demonstrates calvarial distortion (an anlage gland to the paraphysis. Normally, this third ven- elevated inion) due to a Dandy-Walker cyst. tricular gland involutes by the fourth month of gestation. 1 3 / S ABNORMALITIE L CRANIA L DEVELOPMENTA D AN L CONGENITA

. cyst d colloi a t o n locatio l typica e th g demonstratin n sca T C A . 10 . FIG

In some cases, the choroid may be the origin of colloid These lesions are sometimes located on the floor of the . microscopically n see e b n ca a cili y occasionall d an , cysts third ventricle or may sometimes form a pedunculated n ca o Monr f o n forame e th n i t cys e th f o n Impactio e th , Microscopically . space r interpedicula e th n i s mas . hydrocephalus e acut o t g owin h deat n sudde n i t resul lesions are composed of fibrous bundles, neurons, and The often-observed intermittency of symptoms is osten. - tissue l glia sibly relateds tha o a the cyst actinhamartom a gh as wit a d "ball valve,associate y " periodipubert s - Precociou cally occludinm who n gi , the foramenmales n i . Thercommon e e is a higmor s i ht I incidenc . (5) d e of reporte n bee narrowin- fe g n oI f th. e age aqueduc f o r yea t e in on patient e sbefor witp h colloidevelo s d cystssign l . genitalia Symptome on s includn ebetwee mentar lappea deterioratioy pubert s n (fornicaprecociou f o l dams sign - , males age), intermittent headaches related to the position of the and three years of age. Endocrine studies have shown an - hypo o t y secondar s change c endocrinologi d an , tumor g luteinizin d an e testosteron f o s level d bloo n i e increas . damage c thalami - be a hamartom e th r Whethe . factors g hormone-releasin n i s measurement y densit n i s difference f o e Becaus c hypothalami e th o t n connectio k feedbac a s a s have CSF, brait tha n s tissuemas l , and the contentmechanica a r o , s of colloigland s d cysts, thautomatou en a , area diagnosi- re s can n mosfunctio t readill y be determineendocrinologica l d by norma MR h I wit scan s - interfere d an s craniopharyngioma y especiall , lesions r Othe . ning . controversial s main gliomas, may mimic a colloid cyst on CT scanning. Sur- CT or MRI scans show these masses to be nonenhanc- - treat f o m for t bes e th s i s cyst d colloi f o l remova l gica ing, with the same density as brain tissue. ment. The transcallosal approach with the use of the Medical and surgical treatment is necessary to reverse operating microscope has lowered the morbidity for this early secondary sexual manifestions and to prevent early . surgery f o e typ epiphyseal closure. Although histologically benign, ham- d an , pressure l intracrania d increase e caus n ca s artoma CONGENITAL INTRACRANIAL TUMORS early surgical intervention may be necessary. Operative mortality and morbidity should be low when the operat- Hamartomas ing microscope is used. Hormonal suppression with pro- gestational agents and cyproterone acetate provides ad- A hamartom. a iimpossible s as i congenita n resectio l malformatioe complet n n owhe ff normarelie l l ditiona tissue i- n asex ny abnormaSecondar l. locationuncertain . s Thi y e most commoradiotherap f o y n of efficac e Th these tumors are hypothalamic hamartomas attached be- ual characteristics have been reversed by combined sur- tween the tuber cinereum and the mamillary bodies. gical and medical treatments. 32 CHAPTER 3

TeratCMMS Current methods of treatment do not change the poor prognosis in neonates or children. The prognosis in older Teratomas are tumors in which the tissue elements are children depends on several factors: whether the terato- differentiated from all three germ layers but are alien to mas can be resected and whether malignant histological their location- con o t . s Atypical teratomasprocedure g ,Shuntin als. o calleplace n d germinotake e hav s - change mas. do not originate from teratomatous elements and trol hydrocephalus are complicated by the high protein arc not classified as teratomas. Teratomas are relatively level in the CSF. - intracra y primar all f o t percen 5 0. y onl g comprisin , rare Total excision is usually impossible. Treatment con- , neonates n I . population l genera e th n i s neoplasm l nia sists of subtotal resection, followed by irradiation, che- however, 62 percent of tumors are teratoma. s both (6) r o . , Most motherapy occur in the midline cerebral plane, with the pineal l latera d an , vermis r cerebella , region r suprasella , gland ventricles, in decreasing frequency, as the sites of origin. Lipomas In neonates, most teratomas are located in the supra- tentorial space; in patients older than three months, - neona e th g Durin . fossa r posterio e th n i d locate e ar t mos Intracranial lipomas are rare and are usually found at - com A . finding c radiographi l incidenta n a s a r o y autops tal period, teratomas are most common in females. Be- - par d an , callosum s corpu e th f o e midlin e th s i e sit n mo e th , enlarged e ar n childre d afflicte f o s head e th e caus tial or complete agenesis of the corpus callosum may be most common initial diagnosis is hydrocephalus. Baso- cranial extension with gross protrusion of the tumor present. , ambiens a cistern , cinereum r tube e th e ar s site r Othe through a palatobasal deformity can occur. Teratomas - com d an e ag f o s year 5 1 e befor p develo n childre r olde n i d displace e ar s cause e Possibl . angle e cerebellopontin d an mesenchymal cells and inclusion of fat anlage cells at the monly appear simultaneously with diabetes insipidus. s h wit s patient t Mos . closure e tub l neura f o e tim The clinical course is longer and the prognosis better in are asymptomatic; however, lipomas located in the tec- these older children. Carcinomatous changes will deter- mine longevity- dis e . Seizur . hydrocephalus e progressiv e caus n ca n tur n o n see y occasionall e ar s teratoma f o s Calcification . present e b o als y ma s symptom c hypothalami d an s order When the lesion is located in the corpus callosum, f o t enhancemen e moderat A . radiographs l skul e routin - glass e win c characteristi a w sho y ma s radiograph l skul - calcifica f o e evidenc h wit , scan T C n o n show s i s mas e th f o a are n a g surroundin n calcificatio l periphera d shape tions that may represent teeth. MRI scans greatly aid s mas y low-densit a l revea s scan T C d an , density w lo - Cys . masses e thes f o n origi d an t exten e th g delineatin n i e th s unles d indicate y rarel s i y Surger . fat o t l identica n see e b n ca n brai l norma f o t displacemen d an s area c ti . hydrocephalus s cause s mas . 11) . (Fig

MISCELLANEOUS DEVELOPMENTAL OR CONGENITAL ABNORMALITIES

Phakomatosis

Phakomatoses are neurocutaneous disorders of con- genital origin that are associated with tumors and mal- formations of the . Neurosurgery is fre- e diseas g followin e th f o e on n whe d considere y quentl complexes is present: tuberous sclerosis, neurofibroma- tosis, von Hippel-Lindau disease, Sturge-Weber syn- . leptomeninges e th f o a melanom d an , drome

Sinus Pericranii

- differen e th n i d considere e b d shoul i pericrani s Sinu tial diagnosis of cranial meningoceles, meningoencepha- FIG. 11- . Acav sagittas l MRI demonstratinsubcutaneou d an , g typical location ancephalohematoceles d, loceles enhancinn g qualitchildre y on i f an centrallycommo locate t dmos teratomas i n lesio . s Thi . ernomas 3 3 / S ABNORMALITIE L CRANIA L DEVELOPMENTA D AN L CONGENITA

aneurysm. Sinus pericranii are collections of nonmuscu- lar venous blood vessels that communicate directly through the diploe with a major intracranial sinus, usually the superior sagittal sinus. Conversely, venous cavernomas of the scalp communicate with the extra- cranial venous channels. Few symptoms accompany sinus pericranii. The mass, which is more common in the parietal region, is soft and compressible, and it en- g Flexin . performed e ar s maneuver a Valsalv n whe s large a w sho l wil d downwar d hea e th g maneuverin r o k nec e th mass containing venous blood. This lesion has a progres- sive course and will enlarge considerably (Fig. 12). Changes in bone secondary to continuous venous pulsa- tions are usually present. Venous angiography is useful in diagnosing these masses, and surgical removal is rec- ommended.

REFERENCES o t s connection s venou t direc e hav i pericrani s Sinu . 12 . FIG . encephaloceles l occipita r Subtorcula . US s Cavines , PH n Chapma . 1 the sagittal sinus and readily fill whe. n the hea1988;8:86-93 d is in a depenNeumsurg - Pediatr Concepts dent position. 2. Guiffroe R, Curatolo P. Cranial dermal sinuses in childhood and adolescence. Neurochirurgia 1978;21:72-75. 3. Cheek WR, Laurent JP. Dermal sinus tracts. Concepts Pediatr Neu- rosurg 1985:6:63-75. - arach l Congenita . al t e , E h Roua , JP t Lauren . C m Balsubramania . 4 younger than two years old. In the majority of reported noid cysts in children. Pediatr Neurosci (in press). cases, sinus pericranii are congenital in origin, and the 5. Rammer KS, Perlman K, Humphreys RP, et al. Clinical and surgi- walls of the sinuses are lined with endothelium. Trau- cal aspects of hypothalamic hamartoma associated with precocious puberty in a 15-month-old boy. Childs Brain 1980;7:150-153. matic origin has been postulated in some patients, espe- 6. Rubenstein LJ. Tumors of I he central nervous system, Fasicle 6. cially when a fibrous capsule forms similar to a false Washington, DC: Armed Forces Institute of Pathology, 1972.