Wonil Joo

Peritumoral brain edema in meningiomas: correlations between magnetic resonance imaging, angiography, and pathology

BACKGROUND The purpose of this study was to evaluate the radiologic characteristics and pathology related to the formation of peritumoral edema in meningiomas. METHODS Seventy-nine patients with meningioma were examined by MRI and cerebral angiography. The predictive factors possibly related to peritumoral edema, such as patient age, sex, tumor location, tumor size, peritumoral rim (CSF cleft), shape of tumor margin, signal intensity of tumor in T2WI, pial blood supply, and pathology, were evaluated. We defined the edema-tumor volume ratio as EI and used this index to evaluate peritumoral edema. RESULTS Male sex (P = .009), tumor size (P = .026), signal intensity of tumor in T2WI (P = .016), atypical and malignant tumor (P = .004), and pial blood supply (P = .001) correlated with peritumoral edema on univariate analyses. However, in multivariate analyses, pial blood supply was statistically significant as a factor for peritumoral edema in meningioma (P = .029). Male sex (P = .067, P < .1) and hyperintensity in T2WI (P = .075, P < .1) might have statistical probability in peritumoral edema. CONCLUSIONS In our results, male sex, hyperintensity on T2WI, and pial blood supply were associated with peritumoral edema in meningioma that influence the clinical prognosis of patients.

Prognostic value of intra-operative lateral spread response monitoring during microvascular decompression in patients with hemifacial spasm

Hemifacial spasm (HFS) has characteristic and specific electrophysiological features, primarily the lateral spread response (LSR). The aim of this study was to evaluate the correlation between changes in the lateral spread response during microvascular decompression (MVD) and the clinical outcome after MVD. Seventy-two patients with HFS who were treated with MVD were included in this study. Intra-operative facial electromyography (EMG) was performed and brainstem auditory evoked potentials were monitored. In 32 (44.4%) patients, the LSR persisted after MVD. Among these 32 patients, 11 had mild HFS at discharge and six had mild HFS at the 6 month follow up. Out of the 40 patients in whom the LSR disappeared intra-operatively after MVD, five had mild HFS at discharge and four had mild HFS at the 6-moth follow up. The clinical outcome of HFS after MVD does not always correlate with intra-operative EMG abnormality. Therefore, the prognostic value of intra-operative LSR monitoring with respect to long-term results is questionable.

Microsurgical anatomy of the abducens nerve.

The aim of this study is to demonstrate and review the detailed microsurgical anatomy of the abducens nerve and surrounding structures along its entire course and to provide its topographic measurements. Ten cadaveric heads were examined using ×3 to ×40 magnification after the arteries and veins were injected with colored silicone. Both sides of each cadaveric head were dissected using different skull base approaches to demonstrate the entire course of the abducens nerve from the pontomedullary sulcus to the lateral rectus muscle. The anatomy of the petroclival area and the cavernous sinus through which the abducens nerve passes are complex due to the high density of critically important neural and vascular structures. The abducens nerve has angulations and fixation points along its course that put the nerve at risk in many clinical situations. From a surgical viewpoint, the petrous tubercle of the petrous apex is an intraoperative landmark to avoid damage to the abducens nerve. The abducens nerve is quite different from the other nerves. No other cranial nerve has a long intradural path with angulations and fixations such as the abducens nerve in petroclival venous confluence. A precise knowledge of the relationship between the abducens nerve and surrounding structures has allowed neurosurgeon to approach the clivus, petroclival area, cavernous sinus, and superior orbital fissure without surgical complications. Clin. Anat. 25:1030–1042, 2012.

The clinical efficacy of repeat brain computed tomography in patients with traumatic intracranial haemorrhage within 24 hours after blunt head injury.

This study was performed to determine the usefulness of repeated brain computed tomography (CT) within 24 hours of blunt head trauma in patients with traumatic intracranial haemorrhages (ICH) and who were initially treated nonsurgically. Factors associated with the worsening of lesions on repeat CT were evaluated. Medical records of all blunt head trauma patients with traumatic ICH admitted to our hospital from January 2003 to December 2006 were retrospectively reviewed. Patients older than 16 years of age with an initial Glasgow Coma Scale (GCS) of 8 or greater were included. From the results of the repeat CT, patients were categorized as Group 1 (improved or unchanged condition) or Group 2 (worsened condition). A total of 168 patients (mean age of 44.8 ± 19.2; mean admission GCS of 13.42 ± 2.07; male to female ratio 2.1:1) were included. In 161 patients, repeat CT was obtained on a routine basis. In the remaining 7, it was prompted by a worsening neurological condition. The mean time from initial to repeat CT was 10.10 ± 7.25 hours. Based on the results of the repeat CT, 108 patients were included in Group 1 and 60 in Group 2. The mean initial GCS was lower in patients from Group 2 versus those from Group 1 (11.9 ± 2.6 compared with 14.3 ± 0.96; p < 0.001). After repeat CT, 28 (47%) of the patients in Group 2 underwent neurosurgical interventions. Of the 28 surgically treated patients from Group 2, 6 (10%) exhibited neurological worsening and 22 (37%) appeared neurologically stable. According to our data, we suggest that routine repeat CT within 24 hours after blunt head trauma might minimize potential neurological deterioration in patients with either a GCS lower than 12 or with an epidural haematoma or multiple lesions as indicated on initial CT.

Microsurgical anatomy of the infratemporal fossa

The objective of this study is to clearly and precisely describe the topography and contents of the infratemporal fossa. Ten formalin‐fixed, adult cadaveric specimens were studied. Twenty infratemporal fossa were dissected and examined using micro‐operative techniques with magnifications of 3–40×. Information was obtained about the inter‐relationships of the contents of the infratemporal fossa. The infratemporal fossa lies at the boundary of the head and neck, and the intracranial cavity. It is surrounded by the maxillary sinus anteriorly, the mandible laterally, the pterygoid process anteromedially, and the parapharyngeal space posteromedially. It contains the maxillary artery and its branches, the pterygoid muscles, the mandibular nerve, and the pterygoid venous plexus. The course and the anatomic variation of the maxillary artery and the branches of the mandibular nerve were demonstrated. The three‐dimensional (3D) relationships between the important bony landmarks and the neurovascular bundles of the infratemporal fossa were also shown. The skull base anatomy of the infratemporal fossa is complex, requiring neurosurgeons and head and neck surgeons to have a precise knowledge of 3D details of the topography and contents of the region. A detailed 3D anatomic knowledge is mandatory to manage benign or malignant lesions involving the infratemporal fossa without significant postoperative complications. Clin. Anat., 2013.

Spontaneous Spinal Subdural Hematoma Concurrent with Cranial Subdural Hematoma

A 39-year old female presented with chronic spinal subdural hematoma manifesting as low back pain and radiating pain from both legs. Magnetic resonance imaging (MRI) showed spinal subdural hematoma (SDH) extending from L4 to S2 leading to severe central spinal canal stenosis. One day after admission, she complained of nausea and severe headache. Computed tomography of the brain revealed chronic SDH associated with midline shift. Intracranial chronic SDH was evacuated through two burr holes. Back pain and radiating leg pain derived from the spinal SDH diminished about 2 weeks after admission and spinal SDH was completely resolved on MRI obtained 3 months after onset. Physicians should be aware of such a condition and check the possibility of concurrent cranial SDH in patients with spinal SDH, especially with non-traumatic origin.

Delayed diagnosis, due to the associated radiological abnormalities, of spontaneous intracranial hypotension caused by cerebrospinal fluid leakage at C1-2.

Spontaneous intracranial hypotension (SIH) is an uncommon clinical entity that is often diagnosed after a delay, or it is misdiagnosed due to the variety of clinical presentations and the associated radiological findings. We present here a case of SIH associated with chronic subdural haematoma (SDH) and subarachnoid haemorrhage. Following the diagnosis of the SIH, the patient underwent injection of an epidural blood patch for the SIH and burr hole trephination was done for treating the chronic subdural haematoma.

Microsurgical Anatomy of the Oculomotor nerve

The oculomotor nerve supplies the extraocular muscles. It also supplies the ciliary and sphincter pupillae muscles through the ciliary ganglion. The nerve fibers leave the midbrain through the most medial part of the cerebral peduncle and enter the interpeduncular cistern. After the oculomotor nerve emerges from the interpeduncular fossa, it enters the cavernous sinus slightly lateral and anterior to the dorsum sellae. It enters the orbit through the superior orbital fissure, after exiting the cavernous sinus, to innervate the extraocular muscles. Therefore, knowledge of the detailed anatomy and pathway of the oculomotor nerve is critical for the management of lesions located in the middle cranial fossa and the clival, cavernous, and orbital regions. This review describes the microsurgical anatomy of the oculomotor nerve and presents pictures illustrating this nerve and its surrounding connective and neurovascular structures. Clin. Anat. 30:21–31, 2017.

Analysis of the risk factors for development of post-operative extradural hematoma after intracranial surgery.

Abstract Objective. Post-operative extradural hematoma (EDH) is a relatively common complication in patients undergoing intracranial operations. The risk factors associated with the occurrence of EDH are not well described in the literature. The objective of this study was to identify the risk factors and the incidence of post-operative EDH adjacent and regional to the craniotomy or the craniectomy site. Method. This was a retrospective study of 24 (2.6% of total) patients who underwent extradural hematoma evacuation after primary intracranial supratentorial surgery between January 2005 and December 2011. During this period, 941 intracranial operations were performed. The control group (72 patients) was selected on the basis of having undergone the same pre-operative diagnosis and treatment within 2 months of the operations for the 24 hematoma patients. The Glasgow Coma Scale score and operation character (emergency or elective) of the hematoma and control group were individually matched to minimize pre-operative conditional bias. The ages of both groups were individually matched with similar ages within 10 years of each other to minimize age bias. Result. Univariate analysis showed that the significant pre-operative and intra-operative factors associated with post-operative EDH were an intra-operative blood loss of greater than 800 mL (p = 0.007), maximal craniotomy length of greater than or equal to 100 mm (p = 0.001), and craniotomy area of greater than or equal to 71.53 cm2 (p = 0.018). In multivariate analysis, intra-operative blood loss exceeding 800 mL (median of total patients) placed a patient at significantly increased risk for post-operative EDH. Conclusion. The data did not examine established risk factors for post-operative hematoma, such as thrombocytopenia, anti-coagulant and anti-platelet therapy, and a history of heavy alcohol consumption and/or tobacco intake. Recognizing the limitations of the study, large intra-operative blood loss and wide craniotomy area are implicated with an increased risk of post-operative EDH after intracranial surgery.

The cochlea in skull base surgery: an anatomy study

OBJECTIVE The object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea. METHODS Twenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40. RESULTS The cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial nerve and greater petrosal nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem. CONCLUSIONS An understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.