Tailored Surgical Approaches for Foramem Magnum Tumors

Objective To describe our surgical techniques, analyze their safety and their postoperative outcomes for foramen magnum tumors (FMTs). Methods From 1986 to 2014, 34 patients with FMTs underwent surgeries using either the lateral suboccipital approach, standard midline suboccipital craniotomy, or the far lateral approach, depending on the anatomic location of the lesions. Results In the present series, there were 22 (64.7%) female and 12 (35.2%)male patients. The age of the patients ranged from12 to 63 years old.We observed 1 operativemortality (2.9%). A total of 28 patients (82.3%) achieved a score of 4 or 5 in the Glasgow Outcome Scale (GOS). Gross total resection (GTR) was obtained in 22 (64.7%) patients. After the surgery, 9 (26%) patients developed lower cranial nerve dysfunction (LCNd) weakness. The follow-up varied from 1 to 24 years (mean: 13.2 years). Conclusion Themajority of tumors located in the FMcan be safely and efficiently removed usingeither thelateral suboccipital approach, standardmiddlelinesuboccipital craniotomy, or the far lateral approach, depending on the anatomic location of the lesions.

Abordaje retrosigmoideo / Retrogigmoid approach

OBJETIVO: describir en forma detallada, paso a paso, la realización de un abordaje retrosigmoideo. DESCRIPCIÓN: posición: existen 3 posiciones descritas para la realización de este abordaje, semisentada, decubito dorsal y en banco de plaza. Incisión: se extiende desde la parte superior del pabellón auricular hasta 2 cm por debajo del vertice mastoideo, y 1 cm medial a la ranura digástrica. Disección de partes blandas: se realiza una disección subperiostica, teniendo especial cuidado con la vena hemisaria mastoidea (posible fuente de embolia aérea). Craniectomía: es necesario identificar previamente algunos puntos anatómicos de referencia para la ubicación de los senos transverso y sigmoides. En la etapa final de la remoción ósea, se procede al fresado de la porción más superior y lateral del abordaje, con la necesaria exposición de la porción inferior del seno transverso y de la porción medial del seno sigmoides. Apertura dural: se realiza una apertura en forma de letra "C" (lado izquierdo), o letra "C invertida" (lado derecho), con base medial, comenzando en la porción superior y medial de duramadre expuesta. Disección microquirúrgica: dependiendo de la ubicación de la patologia a abordar se debe realizar una retracción gentil del hemisferio cerebeloso hacia medial. En la mayoría de los casos es necesario abrir la cisterna cerebelobulbar, con el objeto de evacuar LCR. CONCLUSIÓN: el refinamiento alcanzado actualmente hace que el abordaje retrosigmoideo sea el más utilizado para el tratamiento de las múltiples patologías ubicadas en la región del ángulo pontocerebeloso. El acceso que proporciona esta vía a la mayoría de los nervios craneales que se encuentran en la fosa posterior, y a sus complejos neurovasculares correspondientes, lo convierte en un abordaje de obligatorio aprendizaje para todo neurocirujano

OBJECTIVE: the aim of this paper is to describe, step by step, the retrosigmoid approach to accessing the cerebellopontine angle (CPA). DESCRIPTION: patient position: three potential positions have been described for this approach: semi-sitting, dorsal decubitus and park bench. Incision: The incision extends from the top of the ear to 2 cm below the mastoid apex, and 1 cm medial to the digastric groove. Soft tissue dissection: A subperiosteal dissection is performed, taking special care to avoid the mastoid emissary vein. CRANIOTOMY: At the outset, it is necessary to identify certain anatomical landmarks to localize the transverse and sigmoid sinuses. Dural opening: The dural incision is made in the shape of the letter "C" on the left side or an inverted letter "C" on the right. Microsurgical dissection: Depending on the location of the pathology being treated, it may be necessary to perform gentle cerebellar retraction medially. CONCLUSIONS: the refinements now achieved with the retrosigmoid approach make it the most widely-used approach for the treatment of lesions located within the CPA. The access provided by this approach to the vast majority of the cranial nerves in the posterior fossa, as well as their neurovascular complexes, makes it a mandatory approach for all neurosurgeons to learn

Nuevo reparo anatómico para la identificación del núcleo dentado en el abordaje suboccipital / New anatomical repair for the identification of the tooth nucleus in the suboccipital approach

Introducción: El abordaje suboccipital constituye una de las vías de acceso más frecuentes a la fosa posterior. Objetivo: La finalidad del presente estudio es definir un reparo anatómico reproducible en la superficie suboccipital del cerebelo que permita ayudar a localizar el núcleo dentado (ND) del mismo. Material y Métodos: Quince cerebelos de adulto fueron estudiados, previa fijación con formol y congelación. Se realizaron cortes axiales y sagitales, con medición de las relaciones entre la fisura horizontal (FH) y el ND. Resultados: La proyección en profundidad de la FH permitió identificar el núcleo dentado en casi todos ellos. Conclusión: La identificación del ND en la cirugía a partir de la FH puede ser considerada un método rápido y confiable. Su utilización pre y perioperatoria podría disminuir las complicaciones derivadas de la lesión de dicho núcleo cerebeloso.

Introduction: The suboccipital approach is one of the most common surgical routes to the posterior fossa.Purpose: The aim of this study was to define a reproductible anatomic landmark in the suboccipital surface of the cerebellum, allowing to localize the dentate nucleus (DN).Material and methods: Fifteen cadaveric specimens (adult brains) were studied, previously fixed with formaldehyde and frozen. Sagittal and axial cuts were performed in the specimens, measuring the relationships between the horizontal fissure (HF) of the cerebellum and the DN.Results: The projection in depth of the HF allowed to identify the DN in almost all of them.Conclusion: The identification during surgery of the DN using the HF maybe a safe and quick method and its usage pre and intraoperatively can lower complications related to lesions of the DN.

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.

A Case of Hypoglossal Neurilemmoma Resected Via Burr-hole Craniectomy

Hypoglossal neurilemmoma is extremely rare. Intracranial hypoglossal neurilemmoma has been reported to the present most commonly as a space-occupying lesion with symptoms of raised intracranial pressure. A 68-year-old women presented with deviation of the tongue to the left on protrusion. Preoperative radiological images revealed an extra-axial mass in and around the hypoglossal canal. The tumor was totally resected via retrosigmoid suboccipital approach with burrhole craniectomy. Histopathological examination verified a neurilemmoma. She had no neurologic abnormality except hypoglossal palsy which recovered completely in six months. Retrosigmoid suboccipital approach with burrhole craniectomy can be an useful approach in intracranial hypoglossal neurilemmoma without extracranial extension or with minimal extracranial extension into the hypoglossal canal.

A Fatal Complication Associated with Combined Posterior Petrous and Suboccipital Approach to a Giant Jugular Foramen Schwannoma

Schwannomas of the jugular foramen, originating from the glossopharyngeal nerve, vagus and accessory nerve represent approximately 0.17-0.72% of all intracranial tumor, and consists of 1.4-2.9% of all intracranial schwannomas. The clinical presentation of these tumors varies significantly according to originated nerve and it's growth pattern. Magnetic resonance(MR) image and temporal bone computed tomography(CT) scan have a major role for diagnosis of such tumor. The treatment of choice is total resection whenever possible. Generally, suboccipital approach is sufficient for the removal of the tumor, but in case with large size, combination of resection of petrous part of temporal bone with or without transection of sigmoid sinus is may be necessory. We have recently experienced one case of giant jugular foramen schwannoma and postoperative fatal complication in a 34-year-old male who was treated with combined posterior petrous and suboccipital approach with transection of sigmoid sinus.

The Translabyrinthine Approach for Removal of the Acoustic Neurinomas: Comparison with the Suboccipital Approach

The result of a series of thirteen translabyrinthine removals of acoustic neurinomas are reported. From 1990 March to 1993 May, thirteen patients with acoustic neuromas underwent translabyrinthine removal at Seoul National University Hospital with cooperation of Department of Neurosurgery and Otolaryngology. In four patients with the medium-sized(11-20 mm) tumors, complete removal with preservation of the facial nerve was possible. In nine patients with the large(21-40 mm) tumors, complete removal of the tumor was possible in seven. Preservation of the facial nerve was possible in all but one, whose facial nerve was incidentally transected at the distal intracanalicular portion and was anastomosed end-to-endly. In one, postoperative leakage of cerebrospinal fluid required reoperation. The results of translabyrinthine approaches were compared with those of suboccipital approaches performed during the same period. In medium-sized or large acoustic tumors, translabyrinthine approach was comparable with suboccipital approach in the rate of total tumors removal, preservation of the facial nerves, and complication.

Dumbbell-Shaped Hypoglossal Neurinoma: Case Report and One-stage Operation

A case of dumbbell-shaped hypoglossal neurinoma is reported. Neurinomas of the hypoglossal nerve are very rare, only 35 cases reported. Of these cases, most are intracranial and only 7 were dumbbell-shaped with both intracranial and extracranial components. The clinical feature of the patient was marked ipsilateral atrophy of the tongue. Magnetic resonance imaging should be included in the examination of tumors, and great aids in planning the radical removal of the tumor. In this one-stage operation which was modified lateral inferior suboccipital craniectomy, the most important aspect was removal of the posterior wall of anterior condylar canal and lateral mass of C1. This approach requires a thorough understanding of microsurgical anatomy of the region of foramen magnum. Patient's postoperative course was uneventful. The literatures concerning this lesion were reviewed.

Surgical Approaches for Tumors Around Foramen Magnum and Craniocervical Junction

The authors treated 26 cases of extramedullary tumors around foramen magnum and craniocervical junction by various surgical approaches between 1982 and February 1993. They are 12 meningiomas, 9 neurinomas, 3 chordomas, 1 teratoma and 1 capillary lymphangioma. Among them, 7 cases are located at anterior portion of foramen magnum, 6 cases at anterolateral portion, 2 cases at lateral portion, 7 cases at posterolateral portion, and 4 cases are posteriorly located. These tumors were attacked via various surgical approaches. 19 cases were treated by conventional suboccipital approach, 5 cases by far lateral suboccipital approach and 2 cases of chordoma by transoral approach which was combined with far lateral suboccipital approach. So, 19 cases of tumors were removed completely, but 7 cases were subtotally removed. There was 1 case of operative mortality and in 2 cases of meningioma there was permanent lower cranial nerve palsy. Pyogenic meningitis due to CSF leakage developed in 2 cases of chordoma which were treated by transoral approach.

A Case of Dermoid in the Cerebellar Hemisphere

Dermoid cysts of the posterior fossa are benign, mostly midline, congenital brain neopasm, usually located above or behind the vermis or adjacent meninges2)18)20), Dermoid lesions are slow growing and may become quite large before producing signs and symptoms12). We have recently experienced a case of dermoid which arised in cerebellar hemisphere. A 32-year old woman who had a history of chronic headache at morining was visited in our department and she was also complained of a egg-sized plapable mass which was growing nature, non-tender, soft, and movable on the right occipital area. On admission, there were no specific localizing and lateralizing neurological abnormalities. Unenhanced CT scan shows hypodense mass in the left cerebellar hemisphere and cystic mass at the right occipital scalp(Fig. 1. A). T1-weighted MR image shows hypointense mass in the left cerebellar hemisphere(Fig. 2. A). The Carotid angiography shows non-specific findings. Paramedian suboccipital approach was performed and mass was removed from the lleft cerebellar hemisphere. The cystic scalp mass was removed totally from the left cerebellar hemisphere. The cystic scalp mass was removed totally from the right occipital area. Diagnosis of dermoid cyst was confirmed pathologically by the specimens obtained from two different sites, left cerebellar hemisphere and right occipital ccalp.