Received: 12 May 2002Revised: 9 July 2002Published online: 19 October 2002© Springer-Verlag 2002

Abstract Case report: The authorspresent a rare case of ossified chron-ic epidural hematoma. A 13-year-oldfemale patient presented with an ossified chronic epidural hematoma.She had sustained a head injuryabout 10 weeks previously and hadreceived conservative care for a de-layed-onset epidural hematoma at alocal hospital. Ossification was iden-tified about 4 weeks after the headinjury and then progressed rapidly. A chronic epidural hematoma with athick collagenous capsule and newlyformed bone was removed 73 days

after the head injury. Conclusion: Anepidural hematoma with mild symp-toms can be treated conservatively.When, however, the hematoma is ob-served not to be naturally absorbedduring serial follow-up examina-tions, surgical removal must be con-sidered, even if the patient’s condi-tion is good, because this entity car-ries the risk of bone calcification andossification.

Keywords Calcification · Chronicepidural hematoma · Ossification

Childs Nerv Syst (2002) 18:712–716DOI 10.1007/s00381-002-0664-2 C A S E R E P O RT

Jong Hee ChangJae Young ChoiJin Woo ChangYong Gou ParkTai Seung KimSang Sup Chung

Chronic epidural hematoma with rapid ossification

Introduction

Calcification or ossification after a chronic subdural he-matoma or cephalhematoma has been reported on sever-al occasions. However, the calcification or ossification ofa chronic epidural hematoma has been reported onlyrarely [3, 7, 9, 15, 18, 19]. Nagane et al. [15] reported anossified and calcified epidural hematoma that was foundincidentally 40 years after a severe head injury. Other au-thors have reported calcified epidural hematomas afterbrain surgery [18, 19]. We present the case of a 13-year-old child who had a chronic epidural hematoma that wasseen to be affected by early ossification approximately4 weeks after a head injury.

Case report

History

A 13-year-old girl was admitted to our hospital after presenting witha headache, nausea and vomiting. She looked acutely ill as a resultof the headache, but was otherwise healthy. She had no neurological

deficits and no bleeding tendency, endocrinological or metabolicdisorders, or other abnormalities were found on blood analyses.

She had been involved in a motor vehicle accident as a pedes-trian. The initial brain computed tomography (CT) showed no ab-normalities except for a mild scalp swelling at the left parietal ar-ea. She was discharged but returned 16 days later complaining ofconstant headache. A follow-up CT showed a hyperdense sub-acute-type epidural hematoma measuring 3.0×4.5 cm in the rightfrontal area. Natural absorption was expected to occur, but a CTscan taken 32 days after the head injury demonstrated that the he-matoma had gradually changed from isodense to hypodense andthat its inner surface was lined with a thin hyperdense layer. A fur-ther CT performed 60 days after the trauma revealed that the innersurface had intensified and thickened. The patient’s headache wasstill persisting, and she was transferred to our hospital 73 days af-ter the head injury. We performed an enhanced brain CT scan: thisdemonstrated an isodense chronic type of epidural hematoma thathad a well-enhanced capsule and a thick and regular (3–4 mm)layer of ossification along the inner border of the hematoma. The

J.H. Chang · J.Y. Choi · J.W. Chang (✉)Y.G. Park · S.S. ChungDepartment of Neurosurgery, Yonsei University College of Medicine, Seoul, Koreae-mail: jchang@yumc.yonsei.ac.krTel.: +82-2-3615624Fax: +82-2-3939979

T.S. KimDepartment of Neuropathology, Yonsei University College of Medicine, CPO Box 8044, Seoul, Korea

Fig. 2A–D Operative findings. A After the bone-flap was re-moved, a yellowish hematoma capsule was identified. B The cap-sule was removed, revealing the newly formed bone, which wasfirmly attached to the dura. C The hematoma capsule after remov-al. D After the hematoma capsule was cut in two, the hematomacavity and the thick capsule were identified

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Fig. 1A–F Serial CT scans. A A CT scan immediately afterthe trauma was sustained,showing no hemorrhage. B A CT scan (day 16 after trau-ma), showing a subacute epidu-ral hematoma in the right fron-tal area. C A CT scan (day 32after trauma), showing a chron-ic epidural hematoma with calcification. D, E CT scans(day 73 after trauma), showingan enhanced hematoma capsuleand ossification. F A postoper-ative CT, documenting total removal of the epidural hema-toma with its surrounding capsule and ossification

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skull over the outer surface of the hematoma was normal (Fig. 1).Skull films showed no fracture line.

Operation

A frontal craniotomy was performed 73 days after the head injury.After the bone flap was removed, a yellowish thick hematomacapsule was identified. It was easily dissected from the surround-ing bony structures and was removed en bloc. It looked like an el-liptical dim-sum (a stuffed steamed dumpling).

The hematoma capsule was cut in two and the yellowish todark brown, liquefied hematoma was identified in the hematomacavity. Newly formed bone at the inner border of hematoma cap-sule was completely covering the underlying dura. It was attachedto the dura, and its thickness was approximately 2–3 mm. Thecapsule thickened to 4 mm at the margin of the orbital fossa, andthe new bony structures were firmly attached to the inner table ofthe calvarium. It was dissected away from the dura and skull andcompletely removed (Fig. 2).

Pathologic findings and postoperative course

Pathologically, a thick fibrotic hematoma capsule and a hematomacavity were identified. In the thick collagenous capsule, hemosid-erin-laden macrophages were scattered but no calcium deposit wasfound. The bony structure that was removed was completely ossi-fied (Fig. 3).

The postoperative course was uneventful, and a postoperativeCT showed that complete removal of the hematoma with the asso-ciated ossification had been achieved and the pressure effect onthe underlying brain parenchyma had been relieved. The patientwas asymptomatic when discharged.

Discussion

Most epidural hematomas, except those with a venoussource and those that are small hematoma and not asso-ciated with a deterioration in mental state, develop rapidly after a head injury and progress to cause neuro-logical deterioration requiring emergency surgical in-tervention. In the pediatric age group an epidural hema-toma is unusual because the dura is relatively firmly attached to the inner table and the suture line of theskull. Rather than bleeding from the middle meningealartery, which is found in adults, in children the cause

Fig. 3A–D Photomicrographs of the hematoma capsule and its os-sification. A A thick fibrotic hematoma capsule (arrow) and he-matoma cavity (asterisks). (H&E, ×1). B, C A thick collagenouscapsule with hemosiderin-laden macrophages (arrowheads). Nocalcium deposits were observed. (H&E, B ×100, C ×200). D Ossi-fication. (H&E, ×200)

of a hematoma can be a hemorrhage of venous blood,which takes longer to accumulate before it causes a sig-nificant mass. This is the reason why 60% of childrenand 85% of infants with epidural hematomas show nodeterioration in the state of consciousness at the time ofinjury and are diagnosed with the chronic form of hematoma [2, 11]. In the case presented here, no hema-toma was found until 16 days after the trauma. The patient’s condition was relatively good, and she experi-enced no neurological deterioration. For these reasons,the primary physician chose to observe the patientwithout performing any surgical intervention. Conse-quently, a collagenous capsule and ossification devel-oped in a very short period while natural absorptionwas still expected.

Persistent cephalhematomas can cause dramaticasymmetry of the skull, as seen in the case of chronicepidural hematoma. The majority of cephalhematomas inneonates are normally absorbed within 1 month and rare-ly require aspiration or surgical intervention. If, howev-er, a cephalhematoma persists for over 1 month, typical-ly it begins to calcify [6, 10, 13]. The hematoma sepa-rates the pericranium from the outer table of the skull,and subperiosteal osteogenesis begins at the attachedmargin of the periosteum around the circumference ofthe bone. This eventually grows over the entire surfaceof the hematoma, ultimately causing skull deformity [5,10, 13].

Calcification is found in 0.3–2.7% of cases of chronicsubdural hematomas and is generally found in childrenand young adults, especially after a shunt operation [1, 4,12, 14, 17]. Calcified chronic subdural hematoma wasfirst reported by von Rokitansky (cited in [17]), who ob-served the condition during autopsy. The mechanism ofthe calcification is still unclear. Afra [1] proposed thatthe calcification process results from regressive changesthat occur in chronic subdural hematomas. Poor circula-tion and absorption in the subdural space, cell necrosis,and hyalinization of connective tissue, caused by thevascular thromboses, are believed to result in calciumdeposition. Some authors have suggested that an inherentmetabolic tendency to calcification is necessary for thedevelopment of calcified chronic subdural hematoma[14], but McLaurin and McLaurin [12] have presented acase of a bilateral subdural hematoma in which calcifica-tion occurred only on one side, and they suggest that lo-cal factors could play a part in calcification. The intervalbetween the initial bleeding and the development of cal-cification is known to vary from 3 months to over3 years [1, 4, 17].

Nagane et al. [15] examined a patient with a calcifiedand ossified epidural hematoma that presented as anasymptomatic intracranial mass found 40 years after ahead injury. They summarized the clinical characteristicsof previously reported calcified epidural hematomas asfollows [3, 7, 9, 15, 18, 19].

1. Head injuries accounted for over 50% of primary epi-dural hematomas, and postoperative bleeding was thesecond most common cause.

2. A preponderance of young males was seen, and themost common initial symptoms were headache andepileptic seizure.

3. The presence of calcification was identified at differ-ent intervals varying between 17 days and 50 yearsafter the primary bleeding.

4. Plain radiographs of the skull revealed a lesion inmost cases, and the calcification was found to devel-op primarily on the dural side of the hematoma in allcases. This is in remarkable contrast to chronic sub-dural hematomas, in which capsule calcification isusually thicker on the outer layer [1].

In the case of chronic epidural hematomas, there may beevidence of a fibrous organization in some older hemato-mas, but the membrane formation seen in chronic subdu-ral hematomas is rare [18]. Iwakuma and Brunngraber[8] found an encapsulated hematoma in 2 of 21 cases ofchronic epidural hematoma, and in 5 cases microscopicossification was found in the thin layer of granulationtissue on dural surfaces. Nakamura and other investiga-tors suggest that a fibroblast layer emerges adjacent tothe dura as early as 4 days after the bleeding, which de-velops into sinusoidal channel layers in 2 or 3 weeks.These fibrous layers then extend toward the cranial vaultfrom the hematoma margin, and subsequently form con-nective tissue layers. This process is a preliminary stagein the formation of a fibrous capsule and ossification [8,16].

Some authors have considered the possibility andthen presumed that there is a pathogenesis of calcifica-tion. Iwakuma and Brunngraber [9] suggest that extradu-ral ossification is an active rather than a regressive pro-cess, and similar to that of the ossification of subduralhematoma. Bone formation does not occur within the he-matoma, but at the junction between the dura and the he-matoma. However, Nagane et al. [15] reported finding achronic epidural hematoma with double shells in the in-ner calcified shell layer that encircled the hematoma andan outer ossified shell only on the dural side. The outershell was produced by the outer dural layer and the innershell may have been formed in the same manner as thecalcification in subdural hematoma. That is to say that achronic epidural hematoma becomes ossified in both anactive and a regressive manner, but the latter requiresmore time.

In the present case, the ossification developed be-cause of an active process. Osteogenesis occurred at theperiosteal layer of the dura that was in contact with theepidural hematoma (Fig. 4). On microscopic examina-tion, calcium deposits were found to be absent within thecollagenous hematoma capsule, but we were able to ob-serve thicker ossification at the peripheral margin of the

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hematoma in surgical specimens. We suggest that thisossification started at the periosteum, which was adher-ent to the bone at its margin and then grew over the en-tire periosteal surface, because the patient was still in theformative years of continuous skull growth. The mecha-nism of ossification in our case differed from that inchronic subdural hematoma, but is similar to that ofcephalhematoma of neonates. The present case is uniquein terms of its very rapid ossification, which occurred

about 4 weeks after head injury and only 2 weeks afterdetection of the hematoma in a patient whose skull os-teogenesis was almost complete. Moreover, we were alsoable to perform serially CT scans and thus observe thewhole course of the ossification.

Conclusion

We examined a 13-year-old girl with a very rare case ofa rapidly ossifying chronic epidural hematoma. It had ac-cumulated slowly owing to its venous source and be-come transformed into the chronic form of hematomaduring the period of conservative care. The ossificationoccurred rapidly within a short period, even though thepatient was at a stage when osteogenesis of the skull hadalmost stopped.

An epidural hematoma with mild symptoms can betreated conservatively. However, when the hematoma isnot seen to be naturally absorbed during serial follow-upsurgical removal must be considered even if the patient’scondition is good, because of the risk of calcification orossification.

Acknowledgement This study was supported by the Brain Korea21 Project for Medical Science, Yonsei University in 2001.

Fig. 4 Locations of and relationship between the epidural hemato-ma, the cephalhematoma, the scalp, the skull and the dura. Calcifi-cation and ossification of an epidural hematoma and of a cephal-hematoma at the periosteal layer of the dura and periosteum, re-spectively

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