枕下远外侧入路的显微解剖及临床应用

目的：研究枕下远外侧入路的显微解剖，并用以指导临床工作。方法：对14具甲醛固定的成人湿性头颅标本进行枕下远外侧入路的显微解剖，并对12例下斜坡及枕骨大孔前方脑干腹侧肿瘤患者进行手术切除。结果：寰椎横突及枕下三角是枕下远外侧入路中的重要解剖标志，磨除枕髁、颈静脉结节能增加术野的暴露。本组12例肿瘤患者中全切除9例，次全切除3例，无手术死亡。结论：研究枕下远外侧入路的显微解剖，有助于安全切除下斜坡和枕骨大孔腹侧肿瘤。     

Sudden Foot Drop Caused by Foraminal Gas Pseudocyst

A foraminal gas pseudocyst is a rare cause of lumbar radiculopathy. The association with a sudden foot drop has not been previously reported. Here, a 67-year-old woman with sudden foot drop on the left side is reported. Computed tomography and magnetic resonance imaging identified a foraminal gas containing lesion compressing the left L5 root at the L5-S1 foramen. The foraminal gas containing lesion compressing the L5 ganglion was successfully removed by the posterior approach. The histological diagnosis was a gas pseudocyst. This unique case of surgically proven gas pseudocyst indicates that it should be included in the differential diagnosis of patients presenting with sudden foot drop.     

Idiopathic bilateral occlusion of the foramen of Monro: An unusual entity with varied clinical presentations

We review our experience with four patients who presented to our Medical Center from 2005–2015 with adult idiopathic occlusion of the foramen of Monro (FM). All patients underwent CT scanning and MRI. Standard MRI was performed in each patient to rule out a secondary cause of obstruction (T1-weighted without- and with gadolinium, T2-weighted, fluid-attenuated inversion recovery [FLAIR] and diffusion-weighted imaging [DWI] protocols). When occlusion of the FM appeared to be idiopathic, further high-resolution MRI with multiplanar reconstructions for evaluation of stenosis or an occluding membrane at the level of the FM was performed (T1-weighted without- and with gadolinium, T2-weighted 3D turbo spin-echo). Occlusion of the FM was due to unilateral stenosis and septum pellucidum deviation in two patients, to an occluding membrane in one, and to bilateral stenosis in one patient. Urgent surgical intervention is mandatory when there are signs of increased intracranial pressure while asymptomatic patients may be managed conservatively. In this patient series, truly bilateral stenotic obstruction of the FM was best managed with ventriculoperitoneal shunt and patients with membranous obstruction or unilateral stenosis with septum deviation were treated endoscopically.     

Surgical management of foramen magnum meningiomas

The objective of the study is to describe our experience in the surgical management of foramen magnum meningiomas with regard to the clinical-radiological findings, the surgical approach and the outcomes after mid-term follow up. Over a 5-year period, 15 patients presenting with meningiomas of the foramen magnum underwent surgical treatment. The medical records were reviewed in order to analyze the clinical-radiological aspects, as well as the surgical approach and the outcomes. Based on the preoperative magnetic resonance imaging exams, the tumors were classified as anterior or anterolateral in the axial slices and clivospinal or spinoclival in the sagittal slices. The lateral approach was used in all cases. However, the extent of bone removal and the management of the vertebral artery were tailored to each patient. Fourteen patients were females, and one was male, ranging in age from 42 to 74 years (mean 55,9 years). The occipital condyle was partially removed in eight patients, and in seven patients, removal was not necessary. Total removal of the tumor was achieved in 12 patients, subtotal in two, and partial resection in one patient. Postoperative complications occurred in two patients. Follow-up ranged from 6 to 56 months (mean 23.6 months).There was no surgical mortality in this series. The extent of the surgical approach to foramen magnum meningiomas must be based on the main point of dural attachment and tailored individually case-by-case. The differentiation between the clivospinal and spinoclival types, as well as anterior and anterolateral types, is crucial for the neurosurgical planning of foramen magnum meningiomas.     

Syringobulbia Caused by Delayed Postoperative Tethering of the Cervical Spinal Cord – Delayed Complication of Foramen Magnum Decompression for Chiari Malformation

Summary  Postoperative tethering of the high cervical spinal cord is a rare cause of neurological deterioration after foramen magnum decompression (FMD) with duraplasty for Chiari type I malformation. A review of the literature revealed that only 5 cases have been reported. This entity is not widely known to occur as a complication of the common surgical procedure for Chiari type I malformation. A 17-year-old boy experienced rapidly progressive neurological deterioration over a 3-month period. FMD and duraplasty with lyophilized cadaver dura had been performed 8 years previously. Follow-up MR images showed that the cerebrospinal fluid (CSF) space dorsal to the cord was gradually disappearing and that syringobulbia had developed. Opening the dura mater of the posterior fossa revealed dense fibrous scarring, arachnoid thickening over the cervicomedullary area, and tethering the cord to the dura from the medulla to C2. The adhesions were dissected free, and the tethering was released. A syringosubarachnoid (SS) shunt was inserted and duraplasty was performed with an expended polytetrafluoroethylene sheet (Gore-Tex). Postoperative MR images demonstrated that the syringobulbia had completely collapsed and that a dorsal CSF space was present. Follow-up MR images provided significant information on the cervical spinal cord tethering after FMD with duraplasty for Chiari malformation. We encourage sharp surgical detethering and duraplasty with Gore-Tex to avoid retethering. Early recognition and treatment of this unusual but important complication are emphasized.     

Morphometric evaluation of the foramen magnum for sex determination: A study from Saudi Arabia

The present study provides a database of various morphometric dimensions of the foramen magnum region in the Saudi population. The objective of this study was to evaluate various measurements of the foramen magnum region for sex determination in the Saudi population by using computed tomography (CT) images. The various radiological measurements of the foramen magnum region were measured in a total of 200 adult subjects of Saudi origin including 100 males and 100 females. Sexual dimorphism was observed in five parameters related to the foramen magnum, namely length of the right occipital condyle (LROC), length of the left occipital condyle (LLOC), width of the foramen magnum (WFM), area of the foramen magnum (AFM) and length of the foramen magnum (LFM). The accuracy to discriminate sex ranged from 65.5% to 62.5% when LROC, LLOC, WFM, AFM, and LFM were considered as individual parameters. When multiple parameters were combined to discriminate sex, the highest accuracy of 71% was achieved.