Microsurgical anatomy of the glossopharyngeal nerve.

The glossopharyngeal nerve is a complicated and mixed nerve including sensory, motor, parasympathetic, and visceral fibers. It mediates taste, salivation, and swallowing. The low cranial nerves, including IXth, Xth, and XIth, are closely related, sharing some nuclei in the brainstem. The glossopharyngeal nerve arises from the spinal trigeminal nucleus and tract, solitary tract and nucleus, nucleus ambiguous, and inferior salivatory nucleus in the brainstem. There are communicating branches forming a neural anastomotic network between low cranial nerves. Comprehensive knowledge of the anatomy of the glossopharyngeal nerve is crucial for performing surgical procedures without significant complications. This review describes the microsurgical anatomy of the glossopharyngeal nerve and illustrates some pictures involving the glossopharyngeal nerve and its connective and neurovascular structures.

Effects of an Infection Control Protocol for Coronavirus Disease in Emergency Mechanical Thrombectomy.

OBJECTIVE: Since the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, neurointerventionists have been increasingly concerned regarding the prevention of infection and time delay in performing emergency thrombectomy procedures in patients with acute stroke. This study aimed to analyze the effects of changes in mechanical thrombectomy protocol before and after the COVID-19 pandemic on procedure time and patient outcomes and to identify factors that significantly impact procedure time. METHODS: The last-normal-to-door, first-abnormal-to-door, door-to-imaging, door-to-puncture, and puncture-to-recanalization times of 88 patients (45 treated with conventional pre-COVID-19 protocol and 43 with COVID-19 protection protocol) were retrospectively analyzed. The recanalization time, success rate of mechanical thrombectomy, and modified Rankin score of patients at discharge were assessed. A multivariate analysis was conducted to identify variables that significantly influenced the time delay in the door-to-puncture time and total procedure time. RESULTS: The door-to-imaging time significantly increased under the COVID-19 protection protocol (p=0.0257) compared to that with the conventional pre-COVID-19 protocol. This increase was even more pronounced in patients who were suspected to be COVID-19-positive than in those who were negative. The door-to-puncture time showed no statistical difference between the conventional and COVID-19 protocol groups (p=0.5042). However, in the multivariate analysis, the last-normal-to-door time and door-to-imaging time were shown to affect the door-to-puncture time (p=0.0068 and 0.0097). The total procedure time was affected by the occlusion site, last-normal-to-door time, door-to-imaging time, and type of anesthesia (p=0.0001, 0.0231, 0.0103, and 0.0207, respectively). CONCLUSION: The COVID-19 protection protocol significantly impacted the door-to-imaging time. Shortening the door-to-imaging time and performing the procedure under local anesthesia, if possible, may be required to reduce the door-to-puncture and doorto- recanalization times. The effect of various aspects of the protection protocol on emergency thrombectomy should be further studied.

Association between height and the risk of primary brain malignancy in adults: a nationwide population-based cohort study.

BACKGROUND: The association between height and the risk of developing primary brain malignancy remains unclear. We evaluated the association between height and risk of primary brain malignancy based on a nationwide population-based database of Koreans. METHODS: Using data from the Korean National Health Insurance System cohort, 6 833 744 people over 20 years of age that underwent regular national health examination were followed from January 2009 until the end of 2017. We documented 4771 cases of primary brain malignancy based on an ICD-10 code of C71 during the median follow-up period of 7.30 years and 49 877 983 person-years. RESULTS: When dividing the population into quartiles of height for each age group and sex, people within the highest height quartile had a significantly higher risk of brain malignancy, compared to those within the lowest height quartile (HR 1.21 CI 1.18-1.32) after adjusting for potential confounders. We also found that the risk of primary brain malignancy increased in proportion with the quartile increase in height. After analyzing subgroups based on older age (≥ 65) and sex, we found positive relationships between height and primary brain malignancy in all subgroups. CONCLUSIONS: This study is the first to suggest that height is associated with an increased risk of primary brain malignancy in the East-Asian population. Further prospective and larger studies with precise designs are needed to validate our findings.

Microsurgical anatomy of the facial nerve.

The facial nerve connections and pathways from the cortex to the brainstem are intricate and complicated. The extra-axial part of the facial nerve leaves the lateral part of the pontomedullary sulcus and enters the temporal bone through the internal acoustic meatus. In the temporal bone, the facial nerve branches into fibers innervating the glands and tongue. After it emerges from the temporal bone it supplies various facial muscles. It contains a motor, general sensory, special sensory, and autonomic components. The physician needs comprehensive knowledge of the anatomy and courses of the facial nerve to diagnose and treat lesions and diseases of it so that surgical complications due to facial nerve injury can be avoided. This review describes the microsurgical anatomy of the facial nerve and illustrates its anatomy in relation to the surrounding bone, connective, and neurovascular structures.

Temperature Difference between Brain and Axilla according to Body Temperature in the Patient with Brain Injury.

OBJECTIVE: Commonly, brain temperature is estimated from measurements of body temperature. However, temperature difference between brain and body is still controversy. The objective of this study is to know temperature gradient between the brain and axilla according to body temperature in the patient with brain injury. METHODS: A total of 135 patients who had undergone cranial operation and had the thermal diffusion flow meter (TDF) insert were included in this analysis. The brain and axilla temperatures were measured simultaneously every 2 hours with TDF (2 kinds of devices: SABER 2000 and Hemedex) and a mercury thermometer. Saved data were divided into 3 groups according to axillary temperature. Three groups are hypothermia group (less than 36.4°C), normothermia group (between 36.5°C and 37.5°C), and hyperthermia group (more than 37.6°C). RESULTS: The temperature difference between brain temperature and axillary temperature was 0.93±0.50°C in all data pairs, whereas it was 1.28±0.56°C in hypothermia, 0.87±0.43°C in normothermia, and 0.71±0.41°C in hyperthermia. The temperature difference was statistically significant between the hypothermia and normothermia groups (p=0.000), but not between the normothermia and hyperthermia group (p=0.201). CONCLUSION: This study show that brain temperature is significantly higher than the axillary temperature and hypothermia therapy is associated with large brain-axilla temperature gradients. If you do not have a special brain temperature measuring device, the results of this study will help predict brain temperature by measuring axillary temperature.

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. © 2016 Wiley Periodicals, Inc.

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.

Microsurgical anatomy of the trochlear nerve.

The trochlear nerve is the cranial nerve with the longest intracranial course, but also the thinnest. It is the only nerve that arises from the dorsal surface of the brainstem and decussates in the superior medullary velum. After leaving the dorsal surface of the brainstem, it courses anterolaterally around the lateral surface of the brainstem and then passes anteriorly just beneath the free edge of the tentorium. It passes forward to enter the cavernous sinus, traverses the superior orbital fissure and terminates in the superior oblique muscle in the orbit. Because of its small diameter and its long course, the trochlear nerve can easily be injured during surgical procedures. Therefore, precise knowledge of its surgical anatomy and its neurovascular relationships is essential for approaching and removing complex lesions of the orbit and the middle and posterior fossae safely. This review describes the microsurgical anatomy of the trochlear nerve and is illustrated with pictures involving the nerve and its surrounding connective and neurovascular structures.

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

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.

Brain Metastases of Papillary Thyroid Carcinoma with Horner's Syndrome.

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy and has relatively favorable prognosis. Blood-borne metastases of PTC are very rare among the thyroid malignancies. Moreover a case of blood-borne central nervous system metastasized PTC with only unilateral Horner's syndrome, and without any abnormalities in laboratory or physical examinations has not been described before. A 53-year-old female patient had been managed in ophthalmologic clinic due to vague symptoms of right monocular blurred vision with eye dryness for 3 months, but showed no signs of improvement. So it was performed a magnetic resonance imaging and magnetic resonance angiography to evaluate the possibilities of cerebral lesion. And a left frontal mass was incidentally found, and the tumor turned out to be a PTC that had metastasized to brain, regional lymph node, cervical, thoracic spine, and lung. We describe a PTC with extraordinary initial symptoms that metastasized to an unusual site. We recommend that if a papillary thyroid tumor with unusual symptoms or at an advanced stage is found, further investigation should be performed for distant metastasis.

Microsurgical anatomy of the trigeminal nerve.

The objective of this study is to review surgical anatomy of the trigeminal nerve. We also demonstrate some pictures involving the trigeminal nerve and its surrounding connective and neurovascular structures. Ten adult cadaveric heads were studied, using a magnification ranging from 3× to 40×, after perfusion of the arteries and veins with colored latex. The trigeminal nerve is the largest and most complex of the cranial nerves. It serves as a major conduit of sensory input from the face and provides motor innervation to the muscles of mastication. Because of its size and complexity, it is essential to have thorough knowledge of the nerve before diagnoses and treatment of the pathologic processes in the orofacial, temporomandibular, infratemporal, and pterygopalatine areas. The trigeminal nerve is encountered with imaging or surgery of the skull base surgery. Thus, a comprehensive knowledge of the anatomy of the trigeminal nerve is crucial for performing the surgical procedures without significant complication.

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.

Focal transnasal approach to the upper, middle, and lower clivus.

BACKGROUND: Carefully tailoring the transclival approach to the involved parts of the upper, middle, or lower clivus requires a precise understanding of the focal relationships of the clivus. OBJECTIVE: To develop an optimal classification of the upper, middle, and lower clivus and to define the extra and intracranial relationships of each clival level. METHODS: Ten cadaveric heads and 10 dry skulls were dissected using the surgical microscope and endoscope. RESULTS: The clivus is divided into upper, middle, and lower thirds by 2 endocranial landmarks: the dural pori of the abducens nerves and the dural meati of the glossopharyngeal nerves. Useful surgical landmarks exposed in the transnasal approach that aid in locating the junction of the clival divisions are the lower limit of the paraclival segment of the internal carotid artery, which is located 4.9 mm above the posterior opening of the vidian canal, and the pharyngeal tubercle. The upper, middle, and lower clival approaches provide access to the anterior midline parts of the previously described upper, middle, and lower neurovascular complexes in the posterior fossa. The nasal and nasopharyngeal relationships important in expanding the transnasal approach to the borders of the clivus are reviewed. CONCLUSION: The transclival approach can be carefully tailored to expose focal lesions in the anterior part of the posterior fossa.

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.

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.

Microsurgical anatomy of the carotid cave.

BACKGROUND: The carotid cave was first described more than 20 years ago, but its relationships to the dural rings defining the clinoid segment of the internal carotid artery (ICA), the carotid collar, and the adjacent osseous structures need further definition. OBJECTIVE: To further define the microanatomy of the carotid cave and its relationships to the adjacent structures. METHODS: : The cave and its relationships were examined in cadaveric specimens using 3 to 40× magnification. RESULTS: The cave is an intradural pouch, found in 19 of 20 paraclinoid areas, that extends below the level of the distal dural ring between the wall of the ICA and the dural collar surrounding the ICA. The distal dural ring is tightly adherent to the anterior and lateral walls of the ICA adjacent the anterior clinoid process and optic strut but not on the medial and posterior sides of the artery facing the upper part of the carotid sulcus where the carotid cave is located. The superior hypophyseal artery frequently arises in the cave. The depth and circumferential length of the cave averaged 2.4 mm (range, 1.5-5 mm) and 9.9 mm (range, 4.5-12 mm), respectively. Aneurysms arising at the level of the cave, although appearing on radiological studies to extend below the level of the upper edge of the anterior clinoid, may extend into and may be a source of subarachnoid space. CONCLUSION: The surgical treatment of aneurysms arising in the cave requires an accurate understanding of the relationships of the cave to the ICA, dural rings, and carotid collar.

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.

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.

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.

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.