Morphometric Study Of Occipital Condyles In North Indian Skulls

Introduction: Occipital condyles are two bony elevations present on either side of foramen magnum in the baseof the skull which articulates with the superior articular facet of the atlas vertebra, connecting the skull with thevertebral column.Objectives: Morphometric analysis of occipital condyles is important for the neuro-surgeons operating for thepathology like degenerative changes of the condyles, neoplasms, and trauma. So the aim of the study wasmorphometric analysis of the occipital condyles and observe any morphological variations of it.Materials and Methods: The study was conducted on 60 occipital condyles of 30 dry adult skulls. Length,breadth, height, intercondylar distance were measured. Relations of hypoglossal canal with the condyles werenoted.Results: The mean length, width and height of occipital condyle were found to be 1.99± 0.33 (right), 2.23 ± 0.33(left), 1.31± 0.28(right) 1.37±0.27 (left), 0.62± 0.17(right) and 0.62± 0.14cm (left), respectively. The mean anteriorintercondylar distance and posterior intercondylar distance were measured as 1.95± 0.34and 3.66± 0.28 cm,respectively. Variations of shape of occipital condyle were kidney like (30%), S-like (23.33%), triangular (16.67%)oval (10.0%), eight like (16.7%) and bipartite condyles (3.33%) respectively. The hypoglossal canal was presentrelated to anterior 1/3 of the occipital condyles in 73.33% case.Conclusions: The shape and morphometric values of occipital condyles are variable. So the knowledge of thesevariations may guide neurosurgeons in transcondylar approach in the management of neoplasms and otherpathology related to this region.

Morphometry And Morphology Of Occipital Condyle Related To The Transcondylar Approach In Dry Skulls

Introduction: The occipital condyles are small, bilateral inferior extensions of the occipital bones. They areintimately related to the foramen magnum and skull base by a number of ligamentous attachments. A variety ofdisease processes may affect the craniovertebral junction. Various lateral approaches have been used to accessthese lesions. Understanding the bony anatomy and variations of occipital condyle is important for theseapproaches. The aim of the present study is to study occipital condyle in detail.Materials and methods: 120 dry human skulls (83 males, 37 females) were studied. The length, width anddifferent shapes of occipital condyle were noted. Various other parameters were measured like anteriorintercondylar distance, posterior intercondylar distance, distance between anterior and posterior end of occipitalcondyle and opisthion.Results: The mean value of occipital condyle length (2.32cm(M) vs 2.22cm(F)) and width (1.29cm(M) vs 1.26cm(F))were present in male and female skulls. The anterior intercondylar distance and posterior intercondylar distanceswere 2.06cm and 4.14cm respectively. Shape of occipital condyle was classified into different types as followingoval, kidney, s shaped, figure of eight, two portioned and deformed. The most common shape of occipital condylewas oval on both sides in males and females.Conclusions: Thorough knowledge of occipital condyle will enable the neurosurgeons to have safe surgery andreduce the morbidity to minimum

Morphometric analysis related to the transcondylar approach in dry skulls and computed tomography / Análisis morfométrico del acesso transcondilar en cráneos secos y en tomografia computarizada

The transcondylar approach (TA) has been used in surgeries to access lesions in areas close to the foramen magnum (FM) and is performed directly through the occipital condyle (OC) or through the atlanto-occipital joint and adjacent portions of the same. The objective of this study is to examine anatomical variations related to the TA by morphometric parameters of the FM, OC and of the hypoglossal canal (HC) in dry skulls and in computed tomography (CT). In 111 skulls, characteristics of the HC, and measures related to the FM, the HC and to the OC were examined. In CT, the measurements obtained bilaterally in 10 patients who underwent examination of the skull base in 1 mm-thick axial helical cuts were the distances from the outer half of the clivus to the opening of the HC; from the lower portion of the OC to the middle of HC; from the inner half of the clivus to the intracranial opening of the HC and to the midpoint of the HC; from the HC extracranial opening to the lower portion of the OC and to the outer half of the clivus. The results of CT measurements are consistent to previous studies of morphometric variations related to the TA, with no significant difference between the measurements obtained in the right and in the left sides, or related to gender. The data obtained by three-dimensional CT images are important in assessing the morphometric variations of pre-surgical patientsof TA.

El acceso transcondilar (AT)ha sido utilizado comoun procedimiento quirúrgico para lesiones cercanas al foramen magnum(FM)y se realizadirectamente a través delcóndilooccipital (CO)o por medio delas porciones atlanto-occipitalconjuntay adyacentesde lamisma.El objetivo del presenteestudio fue examinarlas variaciones anatómicas relacionadas con el AT mediantelos parámetros morfométricos del FM, CO y el canal delhipogloso (CH) en cráneossecos y tomografía computadorizada (CT). En 111 cráneos fueron examinadas las característicasdel CH y tomadas medidas relacionadas con el FM, CO y CH. En la CT, las mediciones se obtuvieron de forma bilateral en10 pacientes que se sometieron a exámen de la base del cráneo en corte axial helicoidal de 1mm de espesor. Las medidas tomadas fueron las distancias: de la mitad exterior del clivus a la apertura del CH; de la parte inferior de las emisiones de CO a la mitad del CH; de la mitad interna del clivus a la apertura intracraneal del CH y hasta el punto medio del CH; de la apertura extracraneal del CH a la parte inferior de las emisiones de CO y hasta la mitad exterior del clivus. Los resultados de las mediciones de CT son consistentes con estudios prévios de los cambios morfométricos en relación con AT, sin diferencia significativa entre las mediciones obtenidas en el lado derecho e izquierdo y ni en relación con el sexo. Los datos obtenidos a través de imágenes en tres dimensiones de CT son importantes para evaluarlas variaciones morfométricas de pre-quirúrgicos en el AT.

Surgical Treatment for Vertebral Artery and Posterior Inferior Cerebellar Artery Aneurysms Via Transcondylar Approach or Transcondylar Fossa Approach / 대한뇌혈관외과학회지

OBJECTIVE: Since posterior circulation vascular lesions are adjacent to important structures such as the brain stem and lower cranial nerves, the acquisition of anatomical information and the careful selection of approaches are essential for the surgical treatment of these lesions. We examined the characteristics and the indications of the far lateral suboccipital approach which exposes lesions without retraction of the brain stem for the treatment of either a vertebral artery (VA) or posterior inferior cerebellar artery (PICA) aneurysm. We present the best diagnostic tool to determine the approaches. METHODS: We have reviewed 11 patients who received surgical treatments between 2005 and 2011 for VA or PICA aneurysms. All of the patients had 3-dimensional computed tomography (3DCT) angiography performed to investigate the relation of the location between the aneurysm and hypoglossal canal. RESULTS: Eight of the 11 patients were treated with the transcondylar fossa approach (TCFA) as their lesions were located proximal to the hypoglossal canal, while three were treated with the transcondylar approach (TCA) as their lesions were located distal to the hypoglossal canal. Of the three patients treated with the TCA, one had temporary palsy of the 11th cranial nerve and the others recovered without any neurological defects. 3DCT angiography showed the relation of the location between the aneurysm and hypoglossal canal. CONCLUSION: The TCFA and TCA are good approaches to expose lesions without retraction of the brain stem. To determine the approaches for the surgery of VA or PICA aneurysms, using 3DCT before surgery is advantageous in understanding the positional relations between the hypoglossal canal and the lesions. During the actual surgery, the posterior condylar canal through which the posterior condylar emissary vein passes can be used as an anatomical landmark for TCFA. With this approach, craniocervical instability can be avoided.

Endodermal Cyst of the Posterior Fossa

We report a case of endodermal cyst of the posterior fossa. A 44-year-old man presented with headache for three months. Computed tomography and magnetic resonance imaging revealed a 6x2.5x2cm sized extra-axial non-enhancing cystic lesion on the ventral aspect to brain stem. To avoid retraction injury to brain stem, far lateral transcondylar approach was selected. Right suboccipital craniotomy and partial removal of occipital condyle with resection of C-1 and C-2 hemilaminae exposed the extra-axial cyst well. The cyst has a whitish thick membrane. It was not adherent to brain stem and lower cranial nerves. Total removal of the cyst was done without difficulty. Histological analysis disclosed a layer of pseudostratified columnar epithelium with basement membrane. The result of immunohistochemical study was consistent with endodermal cyst.

A Case of Large Foramen Magnum Schwannoma

Most intracranial schwannomas originate from the cranial nerve especially CN V, VIII. However, schwannomas from low-cranial nerve are rarely reported. We report a case of large foramen magnum schwannoma in a 26 year-old-man presenting swallowing difficulty, nausea and vomiting. Magnetic resonance image revealed a cystic multilobulated huge mass from midclivus to atlas which compressed brain stem. The mass was removed by far-lateral transcondylar approach and confirmed with schwannoma which originated from hypoglossal nerve.

Ventral Foramen Magnum Meningioma: Case Report

We report a case of a ventral foramen magnum meningioma in a 73-year-old woman presenting with swallowing difficulty, posterior neck pain, gaiting difficulty, progressive motor and sensory deficits in all extemities, and intrinsic muscle atrophy in both hands. Magnetic resonace imaging revealed a huge mass, 4x4x4.5cm in size, located in anterior foramen magnum. We removed the mass by partial condylectomy via far lateral transcondylar approach without neurological deficit and postoperative craniovertebral instability.

Far Lateral Approaches for Intracranial Aneurysms / 대한뇌혈관학회지

Surgical approaches to the posterior circulation aneurysms are difficult and still remained as a matter of debate. Many skull base approaches has been developed to overcome the inadequate exposure of these aneurysm by conventional surgical approaches. Far lateral approaches are an extension of suboccipital approach to expose neurovascular structures around the lower clivus. Aneurysms locating at the vertebral arteries, vertebrobasilar junction and lower basilar artery could be exposed by these approach. However, it is not still evident which kind of far lateral approach is most appropriate for the aneurysms of various locations at these vascular territory. Among the 3 kinds of far lateral approaches, such as far lateral, far lateral transcondylar and extreme lateral transcondylar approach, far lateral approach is not recently used frequently. Far lateral transcondylar approach is good far the aneurysm at the origin of posterior inferior cerebellar artery and the extreme lateral transcondylar approach is useful to expose aneurysms around vertebrobasilar junction. For an appropriate selection of surgical approaches, useful surgical guidelines are mandatory. The recent use of "intermeatal line" and "K lines" and others are of many help for the lower basilar and vertebral artery aneurysms. Surgical approach itself needs knowledge and experience for an adequate performance. Once exposed appropriately manipulation of aneurysms at these locations are not very complicated. Microsurgical anatomy of each surgical step is essential for the sucessful management of aneurysms locating at the lower clivus.

Intracranial Hypoglossal Neurinoma: A Case Report

Hypoglossal neurinoma is vary rare cranial base neoplasm. With the recent advances in the neuroimaging and surgical technique, radical surgical resection is amenable. A case of hypoglossal neurinoma which is located ventral to the medulla is reported. The patient was presented with right hypoglossal nerve palsy, glossal hemiatrophy, and decreased gag reflex on the right side. Magnetic resonance imaging(MRI) revealed an ovoid mass ventral to the medulla with enlarged hypoglossal canal. Because of the ventral location of the mass, far lateral transcondylar approach was selected to minimize the postoperative morbidity. Radical total resection was achieved. This report describes that far lateral transcondylar approach is better than conventional suboccipital approach in regards to satisfactory exposure of the hypoglossal canal and prevention of excessive retraction of the neuraxis.

Modified Transcondylar Approach for a Case of Hypoglossal Neurinoma: Technique

Hypoglossal neurinomas are very rare and those which simultaneously involve the intracranial and extracranial portions are extremely unusual. Using the modified transcondylar approach, the authors successfully removed a dumbbell-shaped hypoglossal neurinoma at the intracranial portion and extending to the anterior upper portion of the axis through the hypoglossal canal. After dividing the cervical musculatures into layers, the vertebral artery was mobilized by opening the foramen transversarium and removing the postero-lateral part of the right occipital condyle, the lateral mass of the atlas and the mastoid tip by means of a small lateral suboccipital craniotomy. This approach offers a wide surgical field and a direct approach to the skull base and upper anterior cervical spine. After total removal of the hypoglossal neurinoma, a very simple supplementary autogenous bone graft was performed between the occipital bone and the lateral mass of the atlas, using the corticocancellous bone fixed with small screws. Postoperatively, the tumor was removed totally and there was no limitation on the cervical rotatory movement. A review of cases of hypoglossal neurinomas and the surgical approaches employed is included in this paper.

Intradural Dissecting Aneurysms Treated by Extreme Lateral Transcondylar Approach(2 cases)

We expierenced two cases of intradural verteral artery dissecting aneurysms. The presenting symptom was subarachnoid hemorrhage in one case and ischemic symptom in the other. The preoperative angiographic finding typically showed fusiform dilatation and proximal and/or distal narrowing of the affected artery. In one case, the vertebral artery was clipped distal to the PICA and in the other case trapping was performed through the extreme lateral transcondylar approaches. This approach permits a control of the aneurysm through the direct view of whole length of the vertebral artery, lower cranial nerves and ventral brain stem. In order to obtain ample view and to save the lower cranial nerves and perforating vessels, jugular tubercle should be sufficiently drilled out. Postoperitive neurological outcomes were favorable except mild hoarseness for some period in trapping case.