Chordae Willisii of the dural sinuses: an anatomical study using magnetic resonance imaging.

PURPOSE: The chordae Willisii (CWs), trabecular projections into the lumen of the dural sinuses, are not well understood. We aimed to explore them using magnetic resonance imaging (MRI). METHODS: Eighty-five patients underwent volumetric contrast-enhanced MRI, while another 30 underwent a fluid-attenuated inversion recovery (FLAIR) sequence in the coronal section. RESULTS: The CWs were detected as linear filling defects lying in the dural sinuses, adjacent to the surrounding dura mater. They were found in the superior sagittal sinus (SSS) in 68.2% of the patients, most frequently in the middle third, with laminar appearance. In 27.1% of the patients, the CWs divided the SSS lumen into separate channels. The CWs were identified in the transverse sinus, transverse-sigmoid sinus junctional area and sigmoid sinus, and straight sinus in 54.1, 47.1, and 8.2%, respectively. On the FLAIR images, dural septi partially dividing the SSS lumen were identified in all patients. In addition, in 73.3% of the patients, fine linear structures were observed in the lumen with inconstant arrangements. CONCLUSIONS: The CWs may be constant structures distributed over the lumen of the intracranial dural sinuses. Contrast-enhanced MRI may be useful for detecting laminar CWs. The FLAIR sequence may be advantageous for delineating the dural septi projecting into the lumen of the dural sinuses.

Acute epidural hemorrhage following burr-hole irrigation for chronic subdural hematoma: A possible association with the diploic veins.

A 50-year-old man presented with headache and left hemiparesis. No noticeable preceding head trauma was observed. Computed tomography (CT) scans revealed a compressive chronic subdural hematoma (CSDH). The patient underwent burr-hole irrigation, during which he was considerably restless. In addition, extensive avulsion was found in the parietal dura mater posterior to the burr hole. CT performed immediately after the surgery revealed the emergence of a thick epidural hematoma (EDH) located posterior to the burr-hole. During emergency craniotomy for the EDH, there was no identifiable injury to the dura mater or the meningeal vessels. However, a review of the CT scans confirmed well-developed diploic spaces just above the center of the EDH, with connecting channels between the diploic spaces and extracranial sites. Based on these observations, we assumed that the diploic vein might have caused the EDH. Diploic veins can cause AEDH after burr hole irrigation for CSDH. Appropriate intraoperative sedation and protective irrigation maneuvers can reduce the risk of such AEDH.

Idiopathic thoracic spinal cord herniation into the vertebra progressing for 3 years.

A 43-year-old, previously healthy man experienced a decreased sensation in the left lower extremity without preceding spinal trauma. At presentation, the patient exhibited slight motor weakness in the left lower extremity, in addition to decreased pain sensation below the ipsilateral T7. Spinal magnetic resonance imaging (MRI) revealed abnormal findings consistent with idiopathic thoracic spinal cord herniation (ITSCH) at the T5/6 level. Computed tomography (CT) revealed a small vertebral erosion at the lower T5. The patient's symptoms gradually progressed over the next 3 years. MRI revealed marked lateral elongation of the cord at the T5/6 and apparent intravertebral cord herniation. The patient underwent ITSCH reduction through T5-6 laminectomies. The herniated cord was vertically long with a bulbous rostral part. Successful ITSCH reduction was achieved and the patient's postoperative course was uneventful. ITSCH is a progressive pathology that requires prompt surgical reduction. Certain ITSCHs may be complicated by intravertebral cord herniation.

Unusually elongated superior thyroid cornu associated with recurrent cerebral embolisms.

The superior thyroid cornu (STC) is a normal anatomic structure that forms part of the thyroid cartilage. Here, we report a patient with unusually elongated and ossified STC that might result in recurrent cerebral embolisms. During a second endovascular therapy for recurrent middle cerebral artery embolism, a segment with an irregular filling defect was noted in the internal carotid artery (ICA), at the C1 level. This defect was unnoticed during the initial endovascular procedure. Three-dimensional computed tomography angiography performed after the second endovascular procedure revealed an ICA segment located between the STC and C1 with a tortuous course and irregular wall of the ICA. Therefore, we assumed that STC compression of the ICA could have resulted in thrombus formation at the site and consequent cerebral embolism. The STC should be considered a structure responsible for cerebral embolism. Careful evaluation of the entire ICA course is imperative prior to performing an endovascular thrombectomy for acute embolic occlusion of the middle cerebral artery.

Are there characteristic indicators for increased pressure in chronic subdural hematoma?

Chronic subdural hematoma (CSDH) is one of the most common neurosurgical disorders. However, no study has yet documented biomarkers indicating increased CSDH pressure. This study aimed to explore such indicators. A total of 50 patients underwent measurement for CSDH pressure during burr-hole irrigation. The mean hematoma pressure was 16.8 ± 7.6 cmH2O with no significant difference between new-onset and recurrent CSDHs. In 12 patients with a CSDH pressure ≥25 cmH2O, further analyses were carried out. Eight of them had bilateral CSDHs. All six patients with a CSDH pressure ≥28 cmH2O suffered headaches before surgery. Two out of three patients with a CSDH pressure ≥29 cmH2O felt nauseous. In statistical analyses, headache was positively correlated with a high CSDH pressure, whereas age and hematoma thickness were negatively correlated with it. Patients' sex, initial Glasgow coma scale score, motor weakness, midline shift on computed tomography scans, and administration of anticoagulants/antiplatelet agents, showed no significant correlation. When patients with bilateral CSDHs are not older adults and suffering headaches, an increased CSDH pressure should be assumed. For such patients, a prompt hematoma evacuation is indicated.

Dural-based large B-cell lymphoma masquerading as a tentorial meningioma.

A 53-year-old woman presented with a 2-week history of headache and vertigo. Computed tomography revealed a hyperdense tumor, measuring 30 × 31 × 36 mm in diameter, in the anteromedial parts of the cerebellar hemispheres. Cerebral magnetic resonance imaging 10 days later revealed an apparent extra-axial tumor with broad attachment to the medial tentorium cerebelli and rapid growth to a diameter of 40 × 41 × 46 mm. Cerebral angiography revealed no obvious feeding vessels or tumor stains. The patient underwent biopsy through the left occipital transtentorial route. The histological appearance was consistent with diffuse large B-cell lymphoma. Intracranial lymphoma may present as a dural tumor that mimics a meningioma. Rapid tumor growth incongruous with benign meningiomas should be assumed to be possible lymphoma, and prompt biopsy should be performed.

Diameters of the optic sheath and superior ophthalmic vein can expand and contract at positional changes: a magnetic resonance imaging study.

PURPOSE: This study aimed to explore the diameters of the optic sheath (OSD) and superior ophthalmic vein (SOVD) in response to positional changes using magnetic resonance imaging (MRI). MATERIALS AND METHODS: Fifty adult outpatients who presented to the hospital underwent thin-slice coronal T2-weighted MRI in the supine position followed by the prone position. RESULTS: The OS and SOV were well delineated in all the patients. The OSD in the anterior orbit was measured in the supine and prone positions on both sides. In addition, the SOVD in the anterior and posterior orbits was measured in the supine and prone positions on both sides. The OSD demonstrated an increase on both sides in 100% of the cases. The SOVD demonstrated an increase on both sides in 94% of the cases, whereas the remaining 6% demonstrated a decrease. The OSD measured at the anterior orbit and the SOVD at the anterior and posterior orbits significantly increased on both sides with positional changes from the supine to the prone position. CONCLUSION: OSD and SOVD may expand and contract in response to alterations in the intracranial pressure and venous flow patterns. MRI examination in the supine position combined with positional changes can help to better understand the OS and SOV as dynamic structures.

Delineation of the central retinal artery using computed tomography: a pilot study.

PURPOSE: The prospective study aimed to examine the central retinal artery (CRA) using computed tomography (CT). MATERIALS AND METHODS: Seventy adult outpatients comprising 32 men and 38 women, at a mean age of 60.6 ± 13.3 years, were enrolled in the study. The patients underwent contrast-enhanced CT. The scan timing was set to start 5.0 s after the circle of Willis began to be delineated. RESULTS: The ophthalmic arteries (OphAs) were comfortably delineated in all. In 97% of the patients, the CRA was delineated from the original site on the OphA to a more distal segment coursing on the optic sheath. Unilateral and bilateral CRA delineations were observed in 44% and 53% of cases, respectively. The delineated CRAs demonstrated highly variable morphologies in terms of the course and length on the optic sheath. In addition, the distance between the original site of the CRA and the posterior limit of the bulb was measured. The mean distance was 18.6 ± 5.0 mm on the right and 17.8 ± 4.3 mm on the left, respectively. No significant right-to-left differences in the measurements (p > 0.05) were observed. CONCLUSIONS: If optimal scan timing is adopted, the CRA segments coursing on the optic sheath can be delineated using contrast-enhanced CT. CT may be a useful diagnostic modality for the CRAs and associated pathological conditions.

Large rhabdoid meningioma presenting prominent hyperintensity in the optic nerve: An indicator of visual disturbance on constructive interference steady-state sequence?

Background: Rhabdoid meningiomas (RMs) are a rare type of malignant meningioma. Here, we report a case of intracranial RM presenting with visual disturbance and prominent hyperintensity in the optic nerve (ON). Case Description: A 20-year-old female presented with a 1-year history of headache. At presentation, her visual acuity (VA) was 20/50 on the right side and 20/40 on the left, with an intraocular pressure of 17 mmHg on both sides. Cerebral magnetic resonance imaging revealed a broad-based tumor in the right frontal convexity. It measured 82 mm × 65 mm × 70 mm in diameter, accompanied by cystic components, and was inhomogeneously enhanced. The intraorbital ONs demonstrated prominent intramedullary hyperintensity on the constructive interference steady-state sequence. Gross total tumor resection was performed and the pathology was consistent with RM. Immediately after surgery, her VA and IOP were 20/17 and 10 mmHg, respectively, with a remarkable resolution of the intramedullary hyperintensity. Conclusion: Prominent hyperintensity in the ON identified in patients with chronic intracranial hypertension may be an indicator of visual disturbance. It can rapidly resolve after resolution of intracranial hypertension with functional recovery.

Large arachnoid granulation protruding into the transverse sinus: A probable cause of intermittent otologic symptoms.

A 69-year-old woman suffered attacks of hearing disturbance and vertigo for seven years. Her otologic and ophthalmological examinations did not show any significant findings. Cerebral magnetic resonance imaging revealed a cystic mass in the left cerebellar convexity. Computed tomography demonstrated a contrast defect of the distal left transverse sinus. Magnetic resonance imaging revealed a cyst protruding into the transverse sinus, and enlarging in the supine. Cerebral angiography demonstrated a congestive venous flow in the left transverse sinus, at the upstream of the cyst. At rest, the venous sinus pressure was 13 cm H2O at the upstream of the cyst and 8 cm H2O at the downstream. When the patient held a breath, the upstream pressure increased to 37 cm H2O, while the maximal downstream pressure was 22 cm H2O. A large AG protruding into the cranial dural sinus may cause intermittent venous congestion and associated otologic symptoms. Movements accompanied by a transient decrease in cardiac venous return and changes in head position can attribute to an enlargement of such AG.

Do the mammillary bodies atrophy with aging? A magnetic resonance imaging study.

PURPOSE: This retrospective study aimed to explore age-related atrophy of the mammillary bodies (MBs) based on their temporal change using magnetic resonance imaging (MRI). MATERIALS AND METHODS: The study included 30 adult outpatients who presented to the hospital and were followed for more than 100 months with annual MRIs. The bi-ventricular width (BVW), third ventricle width (TVW), and bi-mammillary dimension (BMD) were measured on axial T2-weighted imaging and analyzed. RESULTS: The 30 patients comprised 1 in their 40s, 5 in their 50s, 6 in their 60s, 11 in their 70s, 5 in their 80s, and 2 in their 90s. The MBs were consistently detected with left-to-right symmetry. The mean BVW was 32 ± 2.2 mm on the initial (BVW1) and 32 ± 2.4 mm on the last (BVW2) MRI. The mean TVW was 7.0 ± 2.3 mm on the initial (TVW1) and 7.6 ± 2.7 mm on the last (TVW2) MRI. Furthermore, the mean BMD was 9.9 ± 1.3 mm on the initial (BMD1) and 10 ± 1.3 mm on the last (BMD2) MRI. Statistically, no age ranges had a large dimension for BVW1, BVW2, TVW1, TVW2, BMD1, or BMD2. Changes between TVW1 and TVW2 were significantly different in the patients in their 80s; changes between BMD1 and BMD2 were not different for any age range or between sexes. CONCLUSIONS: Aging alone does not seem to promote MB atrophy. In healthy brains, the MBs may be stationary structures throughout life.

Does the superior ophthalmic vein dilate in acute intracranial hypertension due to hemorrhagic stroke?

A 65-year-old man presented with coma. The cranial computed tomography (CT) revealed a massive hematoma in the left cerebral hemisphere, accompanied by intraventricular hemorrhage (IVH) and ventriculomegaly. Contrast examination revealed ectatic superior ophthalmic veins (SOVs). The patient underwent emergent hematoma evacuation. Contrast CT performed on postoperative day (POD) 2 showed a remarkable reduction in the diameters of both SOVs. A second patient, a 53-year-old man, presented with consciousness disturbance and right hemiparesis. CT revealed a large hematoma in the left thalamus, accompanied by massive IVH. Contrast CT demonstrated the bold delineation of the SOVs. The patient underwent endoscopic IVH removal. Contrast CT performed on POD 7 showed a remarkable reduction in the diameters of both SOVs. A third patient, a 72-year-old woman, presented with severe headache. CT revealed diffuse subarachnoid hemorrhage and ventriculomegaly. Contrast CT demonstrated a saccular aneurysm on the internal carotid artery-anterior choroidal artery branching site with the bold delineation of the SOVs. The patient underwent microsurgical clipping. Contrast CT performed on POD 68 showed a remarkable reduction in the diameters of both SOVs. The SOVs may function as an alternative venous drainage pathway in the setting of acute intracranial hypertension due to hemorrhagic stroke.

Penetrating orbitocranial injury by shoji frame: A rare indoor accident in a Japanese style house.

Background: To the best of our knowledge, there are no reports of penetrating orbitocranial injury (POCI) caused by a shoji frame. Case Description: A 68-year-old man fell in his living room and was stuck headfirst by a shoji frame. At presentation, marked swelling was noted in the right upper eyelid, with the edge of the broken shoji frame exposed superficially. Computed tomography (CT) revealed a hypodense linear structure located in the upper lateral sector of the orbit, partially protruding into the middle cranial fossa. Contrast-enhanced CT revealed intact ophthalmic artery and superior ophthalmic vein. The patient was managed with frontotemporal craniotomy. The shoji frame was extracted by pushing out the extradurally located proximal edge from the cranial cavity and simultaneously pulling the distal edge from the stab wound in the upper eyelid. Postoperatively, the patient received intravenous antibiotic therapy for 18 days. Conclusion: POCI can be caused by shoji frames as a result of an indoor accident. The broken shoji frame is evidently delineated on CT, which can result in prompt extraction.

Possible association between minor head injury and intratumoral hemorrhage: A metastatic brain tumor from thyroid carcinoma.

A 78-year-old woman presented after a fall and injury in the left forehead. She had undergone surgery for papillary thyroid carcinoma 14 years prior and breast carcinoma 7 years prior. The patient had exhibited uneventful postoperative courses without relapse or metastasis. Anticoagulants or antiplatelet agents were not prescribed her. At presentation, the patient exhibited no focal neurological deficits. Computed tomography revealed a 19 × 20 mm hemorrhagic lesion in the right temporal lobe. On cerebral magnetic resonance imaging, the center of the lesion exhibited inhomogeneous intensity on both T1- and T2-weighted sequences with heterogeneous enhancement. In contrast, the perilesional hemorrhagic regions, appearing hyperintense on both T1- and T2-weighted sequences, showed temporary regression followed by marked enlargement over the subsequent 123 days. The patient underwent total tumor resection. The microscopic findings of the resected specimens were consistent with papillary thyroid carcinoma. Minor head injuries may trigger intratumoral hemorrhage in metastatic brain tumors. Metastasis should be assumed when patients with a history of thyroid carcinoma present with a solitary parenchymal lesion with the appearance of cerebral cavernous malformation, even if they have been disease free for a long period.

Delineation of the lacrimal vein: a magnetic resonance imaging study.

PURPOSE: To our knowledge, anatomical knowledge about the lacrimal vein (LV) is missed. Therefore, this retrospective study aimed to explore them using magnetic resonance imaging (MRI). MATERIALS AND METHODS: Eighty-one patients who underwent contrast-enhanced MRI and three donated bodies to science were enrolled. RESULTS: On the sagittal images, the measured mean right long (LD) and short diameters (SD) of the lacrimal gland (LG) were 17.3 ± 2.4 mm and 13.7 ± 2.1 mm, while the left LD and SD were 17.0 ± 2.6 mm and 13.6 ± 2.6 mm, respectively. Laterality or sex differences were not found in the LD and SD groups. In addition, no specific age range was associated with a significantly longer LD or SD. LVs were identified in 94% of axial images. Their course was classified into as follows: three types: connecting to the superolateral cavernous sinus (CS), to the superior ophthalmic vein (SOV), and the diploic channels of the greater wing of the sphenoid bone (DCGW). The CS type was the most frequently identified, followed by the SOV and DCGW types. In dissected specimens, the LVs consistently coursed between the posterior margin of the LG and the superolateral part of the CS, above the upper margin of the lateral rectus muscle. CONCLUSIONS: The LV may consistently emerge from the upper posterior margin of the LG. It commonly pours into the SOV or superolateral part of the CS.

Atypical convexity meningioma presenting with photophobia and skull erosion.

A 41-year-old man presented with photophobia. The patient showed a choked disc and right-sided quadrantanopia with an intact sphincter reaction to light stimulation. Computed tomography revealed an isodense mass in the right frontal convexity, accompanied by extensive perifocal brain edema and smooth-contoured skull erosion. On cerebral magnetic resonance imaging, the tumor was dural-based, appeared inhomogeneous intensity on both T1- and T2-weighted sequences, and was intensely enhanced. Magnetic resonance angiography revealed unusually ectatic right-sided middle meningeal and superficial temporal arteries. The tumor, which was elastic hard, highly vascular, and severely adhered to the frontal cortices, was completely resected. The microscopic findings of the resected specimen were consistent with angiomatous meningioma. The patient's photophobia resolved after surgery, with resolution of the optic chiasm compression. Meningiomas arising in the frontal convexity may cause photophobia. Angiomatous meningioma should be considered when a broad-based tumor is found in the cerebral convexity accompanied by skull erosion and extensive perifocal edema.

Delineation of intermammillary relationships using magnetic resonance imaging.

PURPOSE: No study has investigated intermammillary relationships using neuroimaging modalities. This study aimed to explore them using magnetic resonance imaging (MRI). MATERIALS AND METHODS: We enrolled 72 patients who underwent conventional MRI examinations, followed by constructive interference steady-state sequence in the coronal plane. The intermammillary distances (IMDs) were measured at the uppermost level of the intermammillary gap (IMDupp) and the lowest level (IMDlow) of the mammillary bodies (MBs). RESULTS: MBs with varying morphologies were consistently delineated. The appearance of both MBs could be classified into four patterns based on the size and relative levels, with the symmetrical type being the most common. Intermammillary relationships exhibited five patterns. In 69%, the IMDupp was discernible and measured 0.7 ± 0.4 mm, while it was not discernible in 31% due to the presence of intermammillary connection and adhesion. The age distribution did not differ between populations with and without discernible IMDupp. The IMDlow was measured 4.4 ± 0.9 mm. Although the IMDlow was not significantly different between both sexes; it was longer in subjects in their 70s. CONCLUSIONS: Intermammillary relationships show variable morphologies with gaps formed between both MBs. The IMDlow may become more evident in association with age-related increase in the width of the third ventricle and atrophy of the MBs.

Anaplastic oligodendroglioma presenting with apoplectic intratumoral hemorrhage.

A 31-year-old woman presented with a headache and nausea. At presentation, her blood pressure was 114/71 mm Hg with left hemiparesis. Computed tomography revealed a large hyperdense mass in the right temporal lobe accompanied by intralesional calcifications and ventricular perforation. Spot signs were not identified, and cerebral angiography did not reveal any abnormal vasculature. The patient underwent emergency craniotomy assuming an intracerebral hemorrhage. Intraoperatively, grayish tumor tissue was found to intermingle with the clots. Microscopic findings of the tumor revealed neoplastic cells possessing perinuclear halo and cell atypia, and diffusely stained with glial fibrillary acidic protein, which were consistent with anaplastic oligodendrogliomas. However, genomic analyses of the tumor showed non-mutant isocitrate dehydrogenase 1 and telomerase reverse transcriptase, in addition to wild-type O6-methylguanine DNA-methyltransferase. These are equivalent to glioblastoma multiforme. Based on the results, we assumed that anaplastic oligodendrogliomas may develop apoplectic intratumoral hemorrhages that mimic intracerebral hemorrhage. Genomic exploration is recommended for such tumors, coupled with careful follow-up, owing to its potentially aggressive nature.

Does diploic venous flow drain extracranially in the pterional area? A magnetic resonance imaging study.

Background: To the best of our knowledge, no study using neuroimaging modalities has documented calvarial diploic veins (DVs) connected to the extracranial sites. This study aimed to characterize them using magnetic resonance imaging (MRI). Methods: A total of 88 patients underwent thin-sliced contrast MRI. In addition, the DVs coursing through the pterional area were observed on three injected cadaver heads. Results: On postcontrast MRI, the DVs of the pterional area directly drained into the temporalis muscle or supplied branches coursing into the muscle in 43% on the right side and 40% on the left. The DVs and their branches were highly variable in diameter and number. In 9% of cases, the DV of the pterional area was found to drain into an extracranial site and connected to large venous channels distributed in the temporalis muscle. Furthermore, in 17% of cases, the DVs drained into the extracranial sites in the frontal skull region, followed by 9% in the parietal, 2% in the occipital, and 1% in the temporal regions. The DVs coursed superficially in the pterional area on both sides of all three cadaver heads. On one side, the DV in the area was open to an extracranial site. Conclusion: Part of the diploic venous flow drains extracranially in the pterional area. This area may provide an important interface between the calvarial DVs and the extracranial venous system.

Oculomotor nerve segment between proximal posterior and superior cerebellar arteries: an MRI study.

PURPOSE: No study has documented the oculomotor nerve (OMN) segment lying between the posterior cerebral (PCA) and superior cerebellar (SCA) arteries adjacent to the brainstem. The present study aimed to characterize it. METHODS: A total of 71 patients underwent thin-sliced, sagittal T2-weighted magnetic resonance imaging for analysis. RESULTS: The OMN segments lying between the PCA and SCA were identified in all patients. The OMN segment in relation to the PCA and SCA was classified into five types. Of them, the PCA-OMN contact type was the most frequent and found in 35.2% of 71 sides on the right and 39.4% on the left. Also, the PCA-OMN compression type was identified in 12.7% on the right and 15.5% on the left. In these types, the mean distance between the brainstem and contact/compression sites were measured 4.4 ± 2.3 mm on the right and 4.4 ± 1.6 mm on the left. In more than forty percent, the sites were located at the level of the pontomesencephalic junction. CONCLUSIONS: The OMN may be frequently in contact with the PCA near the brainstem. The site located more distal than the central-peripheral myelin junction of the OMN can attribute to a low frequency of neurovascular compression syndrome of the nerve.