Parietal intradiploie eneephaloeele Case report
EDWARD J. KOSNIK, M.D., JOHN N. MEAGHER, M.D.,
AND LOWELL R. QUENEMOEN, M.D.
Division of Neurosurgery and Department of Neurology, Ohio State University Hospital, Columbus, Ohio v' An unusual case is presented of an intradiploic encephalocele surrounding a cerebrospinal fluid cyst. The relationship of this developmental anomaly to the more commonly encountered midline encephalocele and isolated reports of temporal bone encephaloceles are discussed. KEY WORDS
encephalocele
congenital anomaly
NCEPHALOCELES are generally regarded as midline cerebral anomalies in which there is herniation of cerebral tissue outside the confines of the dura mater and skull. Most commonly they occur at the midline from the nasal region to the occiput; they are also reported to occur in the area of the temporal bone. We have recently seen a case in which cerebral tissue herniated through a dural defect into the diploic space of the left parietal bone.
E
Case Report Eight days before admission, this 57-yearold right-handed man had his first generalized seizure, heralded by an expressive aphasia. Postictally he was alert and responsive with no other neurological symptoms. Past history was unremarkable; specifically there was no history of significant head trauma. J. Neurosurg. / Volume 44 / May, 1976
9 intradiploic cerebral cyst
9
Examination. General physical examination was normal; the patient was alert and cooperative and had normal vital signs. No tenderness of the skull was noted and no bruits were heard over the calvaria. Neurological examination was completely normal. A complete blood count, electrolytes, and liver function tests were normal. Skull films demonstrated a large, seemingly lytic process involving the left parietal bone (Fig. 1). Its margins were scalloped with islands of increased density in the central portion. An electroencephalogram demonstrated moderate 4 Hz slowing with spike activity in the left parietal area. A brain scan was normal. Selective left internal and external carotid angiograms were normal. Preoperative diagnoses included benign intradiploic bone cyst, dermoid skull tumor, and metastatic carcinoma (metastatic bone survey was negative). 6]7
E. J. Kosnik, J. N. Meagher and L. R. Quenemoen fluid (CSF) was expressible from the lesion. The center of the cavity of the intradiploic space was lined with cerebral tissue, forming a cystic structure. A craniectomy around the margin of the lesion was performed. Further bone was identified and resected until the base of the lesion was freely discernible. There was a 3 • 3-cm defect in the dura near the center of the lesion through which cerebral tissue seemed to have been extruded. This cerebral tissue appeared to arise from a well-defined area in the parietal cortex. The lesion was amputated at its base and the dura repaired followed by an acrylic cranioplasty. Postoperative Course. The patient's postoperative course has been completely benign with no further seizures. He is being mainFro. 1. Skull film showing the large left parietal tained on anticonvulsant therapy. Microdefect. There appear to be islands of bone forma- scopic examination of the surgical specimen tion in the central portion of this process. revealed cerebral tissue with some normalappearing neurons and moderate gliosis (Fig. 2). Operation. At surgery, after reflecting the Discussion skin, galea, and intact periosteum, several areas in the center of the lesion with a paperHerniation of cerebral tissue into and thin covering of pulsatile osteoid material through a dural defect is not uncommon. were encountered. Some clear cerebrospinal Usually lesions of this type are the encephaloceles seen in children. The size of the anomaly may vary greatly. Indeed, dura, skull, and skin may be absent without cerebral herniation? Patients with dural lacerations after head injury may develop cerebral herniation, the so-called leptomeningeal cyst. This most commonly occurs in children, in whom the sutures are open and the skull is relatively pliable? ,7 Herniation of cerebral tissue may be seen in postoperative cases in which the dura is open and there is some increase in intracranial pressure. Endaural brain hernias may be congenital or may occur after mastoid surgery, middle ear or mastoid infections, or infections following petro-basal skull fracture. 'a The fact that there was such a sharply demarcated area in the cortex and dura through which the cerebral herniation occurred led us to believe that the lesion in our patient was a congenital anomaly. There was actively pulsatile CSF in this somewhat cystic lesion, raising the possibility that there was communication with the ventricle. However, we were unable to demonstrate this at the Fro. 2. Photomicrograph of the lesion. Note time of surgery and no ventriculographic normal-appearing neurons as well as a moderate visualization studies were done. The lesion amount of gliosis. H & E, • 100. appeared to involve almost the entire right 618
J. Neurosurg. / Volume 44 / May, 1976
Parietal intradiploic encephalocele parietal bone. Sartawi, et al., ~ described a patient with unusual skull film changes similar to our case. The defect in their patient was found to be secondary to an arachnoid cyst. Preoperative diagnostic possibilities in our case included an arachnoid cyst, hematogenous bone cyst, dermoid or epidermoid skull tumor, some variant of eosinophilic granuloma, and cavernous hemangioma. There were some areas of unusual density in the center of the lesion suggesting new bone formation as has been described in other skull lesions2 There was incomplete erosion of the outer table with no gross changes in the pericranium. Surgical resection of the abnormal brain in the encephalocele and primary dural repair, followed by immediate acrylic cranioplasty for the bone defect resulted in a successful outcome. References 1. Baron SH: Herniation of the brain into the mastoid cavity. Postsurgical, postinfectional, or congenital. Arch Otolaryngol 90:779-785, 1969
J. Neurosurg. / Volume 44 / May, 1976
2. Dedo HH, Sooy FA: Endaural brain hernia (encephalocele). Diagnosis and treatment. Laryngoscope 80:1090-1099, 1970 3. Kosnik EJ, Sayers MP: Congenital scalp defects: aplasia cutis congenita. J Neurosurg 42:32-36, 1975 4. Matson DD: Neurosurgery of Infancy and Childhood, ed 2. Springfield, Ill: Charles C Thomas, 1969 5. Sartawi M, Schwartz FT, Fox JL: An unusual osteolytic lesion of the skull due to a traumatic arachnoid cyst. Neuroradiology 6:180-181, 1973 6. Taveras JM, Wood EH: Diagnostic Neuroradiology. Baltimore: Williams & Wilkins, 1964
7. Tenner MS, Stein BM: Cerebral herniation in the growing fracture of skull. Radiology 94:351-355, 1970
Address reprint requests to: Edward J. Kosnik, M.D., Division of Neurosurgery, Ohio State University Hospital, 410 West Tenth Avenue, Columbus, Ohio 43210.
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EDWARD J. KOSNIK, M.D., JOHN N. MEAGHER, M.D.,
AND LOWELL R. QUENEMOEN, M.D.
Division of Neurosurgery and Department of Neurology, Ohio State University Hospital, Columbus, Ohio v' An unusual case is presented of an intradiploic encephalocele surrounding a cerebrospinal fluid cyst. The relationship of this developmental anomaly to the more commonly encountered midline encephalocele and isolated reports of temporal bone encephaloceles are discussed. KEY WORDS
encephalocele
congenital anomaly
NCEPHALOCELES are generally regarded as midline cerebral anomalies in which there is herniation of cerebral tissue outside the confines of the dura mater and skull. Most commonly they occur at the midline from the nasal region to the occiput; they are also reported to occur in the area of the temporal bone. We have recently seen a case in which cerebral tissue herniated through a dural defect into the diploic space of the left parietal bone.
E
Case Report Eight days before admission, this 57-yearold right-handed man had his first generalized seizure, heralded by an expressive aphasia. Postictally he was alert and responsive with no other neurological symptoms. Past history was unremarkable; specifically there was no history of significant head trauma. J. Neurosurg. / Volume 44 / May, 1976
9 intradiploic cerebral cyst
9
Examination. General physical examination was normal; the patient was alert and cooperative and had normal vital signs. No tenderness of the skull was noted and no bruits were heard over the calvaria. Neurological examination was completely normal. A complete blood count, electrolytes, and liver function tests were normal. Skull films demonstrated a large, seemingly lytic process involving the left parietal bone (Fig. 1). Its margins were scalloped with islands of increased density in the central portion. An electroencephalogram demonstrated moderate 4 Hz slowing with spike activity in the left parietal area. A brain scan was normal. Selective left internal and external carotid angiograms were normal. Preoperative diagnoses included benign intradiploic bone cyst, dermoid skull tumor, and metastatic carcinoma (metastatic bone survey was negative). 6]7
E. J. Kosnik, J. N. Meagher and L. R. Quenemoen fluid (CSF) was expressible from the lesion. The center of the cavity of the intradiploic space was lined with cerebral tissue, forming a cystic structure. A craniectomy around the margin of the lesion was performed. Further bone was identified and resected until the base of the lesion was freely discernible. There was a 3 • 3-cm defect in the dura near the center of the lesion through which cerebral tissue seemed to have been extruded. This cerebral tissue appeared to arise from a well-defined area in the parietal cortex. The lesion was amputated at its base and the dura repaired followed by an acrylic cranioplasty. Postoperative Course. The patient's postoperative course has been completely benign with no further seizures. He is being mainFro. 1. Skull film showing the large left parietal tained on anticonvulsant therapy. Microdefect. There appear to be islands of bone forma- scopic examination of the surgical specimen tion in the central portion of this process. revealed cerebral tissue with some normalappearing neurons and moderate gliosis (Fig. 2). Operation. At surgery, after reflecting the Discussion skin, galea, and intact periosteum, several areas in the center of the lesion with a paperHerniation of cerebral tissue into and thin covering of pulsatile osteoid material through a dural defect is not uncommon. were encountered. Some clear cerebrospinal Usually lesions of this type are the encephaloceles seen in children. The size of the anomaly may vary greatly. Indeed, dura, skull, and skin may be absent without cerebral herniation? Patients with dural lacerations after head injury may develop cerebral herniation, the so-called leptomeningeal cyst. This most commonly occurs in children, in whom the sutures are open and the skull is relatively pliable? ,7 Herniation of cerebral tissue may be seen in postoperative cases in which the dura is open and there is some increase in intracranial pressure. Endaural brain hernias may be congenital or may occur after mastoid surgery, middle ear or mastoid infections, or infections following petro-basal skull fracture. 'a The fact that there was such a sharply demarcated area in the cortex and dura through which the cerebral herniation occurred led us to believe that the lesion in our patient was a congenital anomaly. There was actively pulsatile CSF in this somewhat cystic lesion, raising the possibility that there was communication with the ventricle. However, we were unable to demonstrate this at the Fro. 2. Photomicrograph of the lesion. Note time of surgery and no ventriculographic normal-appearing neurons as well as a moderate visualization studies were done. The lesion amount of gliosis. H & E, • 100. appeared to involve almost the entire right 618
J. Neurosurg. / Volume 44 / May, 1976
Parietal intradiploic encephalocele parietal bone. Sartawi, et al., ~ described a patient with unusual skull film changes similar to our case. The defect in their patient was found to be secondary to an arachnoid cyst. Preoperative diagnostic possibilities in our case included an arachnoid cyst, hematogenous bone cyst, dermoid or epidermoid skull tumor, some variant of eosinophilic granuloma, and cavernous hemangioma. There were some areas of unusual density in the center of the lesion suggesting new bone formation as has been described in other skull lesions2 There was incomplete erosion of the outer table with no gross changes in the pericranium. Surgical resection of the abnormal brain in the encephalocele and primary dural repair, followed by immediate acrylic cranioplasty for the bone defect resulted in a successful outcome. References 1. Baron SH: Herniation of the brain into the mastoid cavity. Postsurgical, postinfectional, or congenital. Arch Otolaryngol 90:779-785, 1969
J. Neurosurg. / Volume 44 / May, 1976
2. Dedo HH, Sooy FA: Endaural brain hernia (encephalocele). Diagnosis and treatment. Laryngoscope 80:1090-1099, 1970 3. Kosnik EJ, Sayers MP: Congenital scalp defects: aplasia cutis congenita. J Neurosurg 42:32-36, 1975 4. Matson DD: Neurosurgery of Infancy and Childhood, ed 2. Springfield, Ill: Charles C Thomas, 1969 5. Sartawi M, Schwartz FT, Fox JL: An unusual osteolytic lesion of the skull due to a traumatic arachnoid cyst. Neuroradiology 6:180-181, 1973 6. Taveras JM, Wood EH: Diagnostic Neuroradiology. Baltimore: Williams & Wilkins, 1964
7. Tenner MS, Stein BM: Cerebral herniation in the growing fracture of skull. Radiology 94:351-355, 1970
Address reprint requests to: Edward J. Kosnik, M.D., Division of Neurosurgery, Ohio State University Hospital, 410 West Tenth Avenue, Columbus, Ohio 43210.
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