Accounts from 0.3% to 2% of all chronic subdural hematoma ossified subdural chronic hematoma (OSCH) are a very rare disease  . Ossified chronic subdural hematoma is different for calcified subdural chronic hematoma. It is radiological finding. The clinical features of OSCH are different and mimic a brain tumor with headache, weakness, numbness, seizures, memory impairment and complete deficit   . All the cases of OSCH should be treated surgically. We report two cases of patients who suffered from OSCH with a good outcome after the surgery procedure.
2. Case 1
A 13-year-old male patient was admitted for headache, vomited, seizures with left hemiplegia. The past history noticed a head trauma when he was 3-year-old with loss of conscience and hemi paresis. No brain computed tomography (CT) was performed at that time. Upon his admission, the Glasgow coma scale (GCS) was 9/15 and his pupil reflex was normal. The laboratory test results were normal. A brain CT scan showed hemispheric hyper dense ossified rim with a mixed density lesion inside (Figure 1(a)). A bone window CT (Figure 1(b)) revealed that some of the skull near the lesion had become thinner. The patient underwent surgery because of his condition and we made a large fronto-temporo-parietal bone flat. We found a thin dura which permitted to create a new bone flat inside the new ossified lesion. When the lesion was opened, we found inside a brown substance that we later confirmed to be an old hematoma, using histopathology. Without causing any damage to the brain, excision was carefully made by cutting the new bone. The day after surgery, control CT was performed with no brain edema and no bleeding and totally removal of the OSCH (Figure 1(c)). A week later his preoperative symptoms and raised intracranial pressure had resolved and he recovered from his neurological deficit.
3. Case 2
A 17-year-old boy was admitted with 1-month history of progressive right hemi paresis, urinary incontinence and short term memory lack and right side amyotrophic (Figure 2(a)). He had head trauma at age of 5 and suddenly presents a headache, vomiting, tinnitus and seizures and aphasia. The neurological examination revealed right central third cranial nerve palsy and hemi paresis, with Babinsky sign positive and aphasia. The Glasgow coma scale was evaluated to 10/15. A brain CT scan was performed and showed a hyper dense mass with on bone window an ossified subdural chronic hematoma with mass effect (Figure 2(b)). The mass was removed by craniotomy and confirmed OSCH which was thickly ossified on its surface. The surgical strategy concerns inner surface of dura mater and the ossified layer which was thick and extended. We were able to drill the ossified layer above the inner membrane (Figures 2(c)-(e)). One week post operation, CT revealed that the hematoma had been totally resected and the brain did not expand (Figure 2(f)). Over one month later his preoperative motor symptoms, seizures and aphasia had resolved and he became capable of all activities of daily living.
Chronic subdural hematoma is usually one of the complications of head trauma. The pathogenesis of Ossified subdural chronic hematoma (OSCH) is not completely clear   . Many authors reported that local metabolic, poor circulation and absorption in the subdural space could be the factors that caused calcification    . However, the hemorrhage is thought to progress from hyalinization to calcification and it takes at least six months for calcification to develop. But the mechanism of ossification of subdural chronic hematoma still unclear. OSCH may be observed more frequently in children and young adult
Figure 1. CT scan of the brain showing a large hemispheric mixed hyper dense lesion (a) and on bone window (b) an ossified rim which was totally removed (c).
Figure 2. Clinical view of hemi amyotrophic right side (a); pre operative brain CT scan showing a temporo parietal hyper dense mass (b) with on bone window an ossified subdural chronic hematoma (b'). intra operative view showing craniotomy bone flap (c) (green arrow), dura thinner dura mater (d) (blue arrow) and ossified rim of OSCH (e) (yellow arrow). Post operative brain CT scan showing total removal of the mass.
than older people  . In our cases, the patients lived for a long time with a neurological deficit after head trauma in childhood. The first (case 1) has past history about ten years head trauma with deficit and the second twelve years past history (case 2). The mechanism of ossification is quite longer than the calcification according to the cases reported.
The clinical features of OSCH and subdural chronic hematoma in these cases are similar to those non calcified or ossified   . The symptoms are acute headache deteriorisation of consciousness (case 1&2). This symptomatology indicates that OSCH may have caused a chronic but mild increase in intracranial pressure that was high enough to cause neurological symptoms. Both of the patients were performed CT scan and the lesions appeared as OSCH. The patients underwent surgery for total removal of the lesions as many authors recommended for symptomatic patients  . In these cases, OSCH is diagnosed as mass effect, a surgical procedure should be considered because some OSCH can involve an active lesion that grows like a neoplasm. It has been suggested that the presence of brain atrophy may have been the reason why some cases are asymptomatic; which is not the case in case 2. The CT scan showed an ischemic or cerebral infarction. Despite this the patient present twelve years after a symptoms and recovered totally after a radical removal.
Ossified Subdural Chronic Hematoma is a rare disease with a different clinical feature. The management is surgical when the symptoms are masse effect syndrom. Taking care during the procedure of the dissection from the parenchyma is the key for this surgery.
The study was approved by the Research Ethics committee of the affiliated Hospital of Parakou University.
The patient’s family had given their consent for the case reports to be published
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