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At least 19 recordsLinked to original sources
PubMed2001

Sudden unconsciousness during a lesser occipital nerve block in a patient with the occipital bone defect.

Occipital nerve block is usually considered to be a very simple and safe regional anaesthetic technique. We describe a case of sudden unconsciousness during a lesser occipital nerve block in a patient with an occipital bone defect. A 63-year-old man complained of headache, which was localized to the right occipital region. A right lesser occipital nerve block with a local anaesthetic was performed for treatment. During the lesser occipital nerve block, the patient suddenly became disturbed and lost consciousness. Two hours after the incident, the patient was fully awake without neurological sequelae. He had previously undergone a microvascular decompression for right trigeminal neuralgia. The patient had a bone defect following craniotomy. We believed that the loss of consciousness during lesser nerve block may be due to a subarachnoid injection. Occipital nerve block is relatively contraindicated in the presence of a bone defect.

Anesthetics, Local↗
PubMed1993

Aneurysmal bone cyst of the occipital bone: case report.

A 21-year-old male with a painful, expanding mass in the occipital bone was operated on. The clinical findings were suggestive of a malignant tumor. However, appearance and histological examination of the operative specimen identified it as being an aneurysmal bone cyst, a rather rare nonneoplastic lesion of unknown origin. Besides demonstration of the case, a review of the relevant literature is presented.

Adult↗
PubMed1990

Elevation of the petrous bone caused by hyperplasia of the occipital bone presenting as hemifacial spasm: diagnostic values of magnetic resonance imaging and three-dimensional computed tomographic images in a bone anomaly.

A case of elevation of the petrous bone due to hyperplasia of the occipital bone presenting as hemifacial spasm is reported. A 44-year-old man sought treatment for twitching of the buccal muscles on the right side that progressed rapidly in severity within 2 weeks of the onset. The anatomical details of the petrous and occipital bones were delineated clearly by computed tomographic scans of a bone window level. Details of the brain stem were shown by magnetic resonance images. The bone anomaly was displayed more realistically by three-dimensional computed tomographic reconstructions. The faithful representation of structures with these radiological studies should be mandatory, to prepare the surgical planning of such a complicated bone anomaly.

Adult↗
PubMed2002

Fibrous dysplasia in combination with aneurysmal bone cyst of the occipital bone and the clivus: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Fibrous dysplasia of the cranium is a relatively uncommon disorder that affects primarily the anterior cranial region; its occurrence in the cranial base in combination with aneurysmal bone cyst (ABC) constitutes an extremely rare condition, only two cases of which have been reported previously in the literature. It is important to recognize and treat these cases properly because of the special location in the cranial base and the possibility of neural structure impingement. CLINICAL PRESENTATION: We report the case of a 19-year-old man with a slowly enlarging mass of the occiput, with computed tomographic and magnetic resonance imaging revealing involvement of petrous and basisphenoid bone and growing ABC. INTERVENTION: Open biopsy confirmed the diagnosis of fibrous dysplasia. Partial excision of the lesion and removal of the ABC were performed in a second stage after embolization. CONCLUSION: ABC associated with fibrous dysplasia of the cranial base may enlarge rapidly after puberty and require excision. This is facilitated by preoperative embolization.

Adult↗
PubMed1983

Aneurysmal bone cysts of the occipital bone.

Two cases of aneurysmal bone cysts are reported. Each patient presented with a palpable mass in the occipital region and signs of compression of structures in the posterior fossa. One of the cases is unique, in that the aneurysmal bone cyst was associated with an epidural hematoma in the posterior fossa. The pertinent literature is reviewed.

Adolescent↗
PubMed1975

Biometry of the human occipital bone.

A biometric study of the occipital bone was carried out on 125 dissecting room skulls; it brought out the following points: 1. The occipital squama, despite its dual histological origin, constitutes a stable anatomical structure because its dimensions remain in correlation if the size factor is maintained constant. 2. The parts around the foramen magnum also show 'organic correlations', but these are virtually unrelated to the squama. 3. The pars basilaris is biometrically independent of the squama; it could well be described with, and regarded as an extension of, the body of the sphenoid if it were morphologically separated from the rest of the occipital bone; there is thus good cause to describe in Man a spheno-occipital 'clivus'. 4. The study of the curvatures of the squama shows that fossil Man agrees with present day Man in that when the occipital is rounded, the parietal is not, and the skull is low and elongated. 5. Sexual differences are more easily described than measured. The shape of the occipital condyles has greater value for sex determination than that of the nuchal crests. 6. Attempts were made to estimate cranial capacity from isolated occipital bones, but one had to be content with a fairly large margin of error. Several types of formulae are nevertheless offered to human palaeontologists in the hope that they might satisfy their need to get a rough indication of cranial capacity from occipital material.

Cephalometry↗
PubMed1985

Hypoplasia of the basi-occipital bone and persistence of the spheno-occipital synchondrosis in a patient with transitory supplementary fissure of the basi-occipital.

The author had the opportunity to observe the progressive development of a special form of basilar impression characterized by transitory supplementary fissure of the basi-occipital bone, persistence of the spheno-occipital synchondrosis and hypoplasia of the basi-occipital. He proposes to dissociate the general concept of basilar impression and to consider anatomo-clinical entities such as the example described in this paper.

Adult↗
PubMed1992

Ossification of the membranous portion of the squamous part of the occipital bone in man.

The squamous part of the occipital bone consists of 2 parts, supraoccipital and interparietal. The supraoccipital develops both in cartilage and membrane. At the upper margin the bone lying between the superior and highest nuchal lines known as the torus occipitalis transversus is ossified in membrane by a pair of centres. This part of the supraoccipital represents the original membranous part of the primitive occipital bone of lower animals where the interparietals form part of the parietals. This segment of bone is labelled as the intermediate segment which probably never separates from the cartilaginous supraoccipital. The interparietal bone lying above the highest nuchal lines develops in membrane by 2 pairs of centres, 1 pair for the lateral plate and the other for the medial plate. Each centre consists of 2 nuclei. Failure of fusion between these centres or their nuclei with each other and the supraoccipital may give rise to various anomalies in the interparietal region which are discussed. This is the true interparietal bone which has migrated from the parietals of lower animals during evolution to become part of the occipital bone in man. When it appears as an anomaly in the form of an independent separate bone, the suture between it and the supraoccipital lies at the level of highest nuchal lines. There is no pre-interparietal bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Embryonic and Fetal Development↗
PubMed2001

Morphologic and radiologic anatomy of the occipital bone.

Several diseases may cause craniovertebral instability warranting occiput-cervical fusion. As occipital screw and rod constructs are becoming more popular, requiring that screws be placed either medially or laterally in the occipital bone, the need for clearer anatomical and computed tomography (CT)-confirmed data regarding the relative thickness of the occiput in its various localities has become more critical. In 18 cadaveric specimens, the occipital bone was divided into 35 measurable segments. Transversely, the occipital bone was divided into five lines starting at the level of the inion; horizontal lines then proceeded inferiorly in 1-cm segments, 1, 2, 3, and 4 cm below the level of inion. In a comparable fashion, the occipital bone was divided vertically, starting at the midline, and proceeding laterally also in 1-, 2-, and 3-cm segments. Anatomical measurements of thickness were directly performed using a Vernier caliper. Results were directly correlated with axial CT measurements of bony thickness. Anatomical and CT measurements closely correlated within the same specimen, but there was significant interspecimen variability. The marked differences in the occipital bone anatomy noted between specimens indicates that patients undergoing occipital screw placement for cranial-cervical instability would benefit from preoperative occipital CT evaluations.

Cadaver↗
PubMed1996

An anatomic study of the thickness of the occipital bone. Implications for occipitocervical instrumentation.

STUDY DESIGN: The authors measured the thickness and quality of occipital bone regions to determine screw placement during occipitocervical fusion and described the projection of the posterior dural venous sinuses. OBJECTIVE: This study provides anatomic data relevant to areas of screw placement into the occiput during occipitocervical fixation. SUMMARY OF BACKGROUND DATA: Few reports exist regarding the morphometrics of the occipital bone and intracranial structures relevant to occipitocervical fusion. METHOD: The thickness of the posterior inferior occipital bone was measured relative to a 10 x 5 cm grid. Sections were evaluated grossly and histologically. The projections of the posterior dural venous sinuses were determined by direct measurements. RESULTS: The maximum thickness of the occipital bone, which ranged from 11.5 to 15.1 mm in males and from 9.7 to 12.0 mm in females, was at the level of the external occipital protuberance. The occipital bone was thicker than 8 mm in an area extending laterally from the external occipital protuberance for 23 mm and consisted of dense cortical bone with little or no diploic bone. The projection of most of the torcula on the external surface of the occipital bone was located superior to the center of the external occipital protuberance (mean, 12.6 mm superior and 4.7 mm inferior to external occipital protuberance), whereas that of the transverse sinus was distributed more evenly above and below the external occipital protuberance (mean, 7.3 mm superior and 6.5 mm inferior). CONCLUSIONS: Screws that are 8-mm long may be inserted in the region of the superior nuchal line (Level 0) extending 2 cm laterally from the center of the external occipital protuberance, 1 cm from the midline at a level 1 cm inferior to the external occipital protuberance (Level 1), and 0.5 cm from the midline at a level 2 cm inferior to the external occipital protuberance (Level 2). The major dural venous sinuses are situated immediately beneath the thickest regions of the occiput and are at risk of penetrative injury during screw placement.

Bone Plates↗
PubMed1977

Developmental abnormalities of the occipital bone in human chondrodystrophies (achondroplasia and thanatophoric dwarfism).

Specific developmental malformations have been demonstrated in the occipital bone of two chondrodysplastic disorders (achondroplasia and thanatophoric dwarfism). Analysis of these malformations indicates that the occipital bone is primary affected in these disorders. In both cases, the endochondral-derived components of the occipital bone (the basioccipital, the two lateral parts, and the planum nuchale of the squama occipitalis) have failed to grow properly and are smaller and shorter than normal. On the other hand, the planum occipitalis of the squama, which derives from intramembranous ossification, is unaffected. In addition, the nature of these abnormalities indicates that the occipital synchondroses, together with the epiphyseal plates of other bones, are primarily affected in these two chondrodysplasias. The components of the occipital bone formed between the affected synchondroses failed to grow normally. The resulting malformation of the occipital bone is undoubtedly the cause of the shortening of the posterior cerebral fossa and of the considerable narrowing of the foramen magnum often described in these chondrodysplasias. It is postulated that growth disturbances between the affected occipital bone and the unaffected central nervous system results in the inadequacy of the posterior cerebral fossa and the foramen magnum to accommodate the growing brain. Consequently, compression of the brain at the posterior cerebral fossa or the foramen magnum levels could occur and thus lead to neurologic complications such as hydrocephalus and compression of the brain stem. It is suggested that the surgical removal of the fused posterior border of the lateral parts of the occipital bone (partial nuchalectomy) for the purpose of enlarging the narrow foramen magnum may be indicated in those chondrodysplastic children who develop these types of neurologic complications.

Achondroplasia↗
PubMed1995

Microscopic age changes in the human occipital bone.

The value of histological examination of the human occipital bone for estimation of age-at-death was assessed. Undecalcified sections of occipital bone from eighteen male Caucasian subjects between the ages of 21 and 70 years were prepared for analysis using polarized light microscopy. The fractional volumes of primary osteons, secondary osteons, osteon fragments, and lamellar bone in both the outer and inner cortical tables were determined. It was found that with increasing age there is a decrease in the fractional volume of primary osteons and a significant decrease in the fractional volume of lamellar bone. The fractional volume of secondary osteons was not found to change significantly with age, while the fractional volume of osteon fragments significantly increases. The microscopic results reflect the continuous process of bone remodeling that is responsible for the variation in cortical parameters with age and is the primary basis for age predicting methods. While observable changes in the occipital bone do occur with increasing age, the amount of random variation in the parameters examined preclude their use for accurate age estimation.

Adult↗
PubMedDate not supplied

Development of the basilar part of the occipital bone in normal human fetuses.

The present study aims to investigate the normal maturity and growth of the basilar part of the occipital bone evaluated radiographically and histochemically during the first half of prenatal life. The material consisted of cranial bases from 49 normal human fetuses and, in addition, three separate occipital bones deviscerated from normal fetuses. The normal development of the basilar part of the occipital bone was divided into five maturity stages (OB-I to OB-V). Microscopic investigation confirmed the macroscopic findings described. For each stage the ventro-dorsal dimension of the occipital bone component was measured (LEN). The stages of (OB-I to OB-V) were related to gestational age (AGE), crown-rump length (CRL), LEN, and to the length of the humeral bone (HL). Close accordance was registered between OB stages and length values of the basilar part of the occipital bone, LEN, and length of the humeral bone, HL. A highly significant positive correlation was found between LEN and the parameters AGE, CRL, and HL values (P < 0.001). Standards for normal development of the basilar part of the occipital bone are considered important for evaluation of the pathological prenatal development of the cranial base.

Gestational Age↗