Craniocervical Junction Research Articles

Short-Latency Trigeminocervical Reflex Obtained Without Muscle Activation: Topographic Distribution and Methodological Approach

Purpose: Electrical stimulation of trigeminal nerve branches elicits early and late reflex responses in the cervical muscles, known as the trigeminocervical reflex (TCR). This study aimed to evaluate the neurophysiological aspects, stimulation patterns, and topographic distribution of short-latency TCR components in humans in the absence of voluntary muscle activation. Methods: This prospective observational study included 30 participants. Trigeminocervical reflex responses were simultaneously recorded from the bilateral sternocleidomastoid, trapezius, and splenius capitis muscles (without voluntary muscle activation), after electrical stimulation of the supraorbital and infraorbital nerves. Two different stimulation protocols were evaluated: a 3 Hz stimulation protocol (using averaging) and a single-pulse stimulation protocol. Results: Using a 3 Hz stimulation protocol, short-latency TCR responses were recorded in the sternocleidomastoid, trapezius, and splenius capitis muscles, ipsilateral and/or contralateral, but with variable recordability depending on the recording site. The most reliable response was obtained in ipsilateral sternocleidomastoid muscle. To the best of our knowledge, this is the first study to demonstrate the elicitation of short-latency TCR components in the sternocleidomastoid muscle in the absence of voluntary muscle activation in humans without craniocervical junction disorders or lower brainstem abnormalities. Conclusions: The choice of an appropriate stimulation protocol is particularly relevant for recording short-latency TCR components, considering that the visualization of early or late responses seems to be facilitated by different stimulation methodologies.

Covariation in the Craniocervical Junction of Carnivora.

The craniocervical junction is the transition between the skull and the vertebral column that provides mobility while maintaining sufficient stability (i.e., protection of the brainstem and the spinal cord). The key elements involved are the occiput, the first cervical vertebra (CV1, atlas) and the second cervical vertebra (CV2, axis). The two vertebrae forming the atlas-axis complex are distinct in their morphology and differences in form have been linked to differences in ecological function in mammals. Here, we quantified the morphological diversity of the cranium, CV1 and CV2 in a sample of Carnivora using 3D geometric morphometrics to reveal phylogenetic and ecological patterns. Our results indicate that the observed variation in CV2 is related to the taxonomic diversity (i.e., strong phylogenetic signal), whereas variation in CV1 appears to be decoupled from species diversity in Carnivora and, thus, is likely to reflect a functional signal. The phylogenetically informed correlation analyses showed an association between the CV1 morphology and diet. Taxa that primarily feed on large prey tend to have larger transverse processes on CV1 which provides larger muscle attachment areas and may correlate with stronger muscles. The latter needs to be verified by future quantitative covariation analyses between bone and muscle data. Morphological peculiarities within Pinnipedia and Mustelidae could be explained by differences in terrestrial locomotion between Phocidae and Otariidae and the exceptional defensive behavior (i.e., handstanding) in Mephitidae. Despite differences in the degree of morphological diversity, covariation between cranium, CV1 and CV2 morphology is consistently high (≥ 0.82) highlighting that overall, the craniocervical junction is an integrated structure, but there are traits that are not constrained.

Modified salpingopharyngeus myomucosal flap: a novel technique for skull base reconstruction.

Advancements in endoscopic skull base surgery have enabled complex tumor resections, necessitating a variety of reliable reconstructive techniques to repair resultant defects. Vascularized flaps represent optimal options, but frequently used local pedicled intranasal flaps may be unavailable due to tumor invasion or prior surgery. This study applies a modification to the previously described salpingopharyngeus myomucosal flap (Dicle flap) with potential for its use in extensive endoscopic skull base surgery defect's repair. Cadaveric dissections (n = 5) were performed utilizing endoscopic visualization to access the skull base via endonasal and transoral routes. A superiorly based posterior pharyngeal myomucosal flap along the salpingopharyngeus muscle was elevated off the superior pharyngeal constrictors, preserving their vascular pedicles. This combined flap could be 180 degrees transposed to reconstruct clival defects up to the sella turcica. The modified salpingopharyngeus myomucosal flap (Modified Dicle flap) provided approximately 40 cm2 of robust vascularized tissue based on the ascending pharyngeal artery and random posterior pharyngeal vessels. It was sufficiently mobilized to cover extensive skull base defects in the craniocervical junction, sella turcica, and protecting the exposed internal carotid artery segments. The modified Dicle flap offers a viable reconstructive option for extensive endoscopic endonasal skull base defects when commonly utilized vascularized flaps are unavailable. Further research on clinical cases is warranted to investigate postoperative function and refine techniques to minimize donor site morbidity. Not applicable.

Pediatric Cervical Spine Trauma: A Narrative Review.

Narrative review. To provide an updated overview of pediatric cervical spine trauma. Pediatric cervical spine trauma can cause debilitating morbidity and mortality and neurological impairment. The unique anatomic features of the developing cervical spine can predispose children to injuries. We reviewed the pediatric cervical spine trauma literature in PubMed and EMBASE. Pediatric cervical spine injury occurs in 1%-2% of pediatric trauma. The most frequent cause is motor vehicle collisions, with sports-related injuries being more common in older children. Larger head-to-body ratios and tissue elasticity can predispose young children to a greater risk of injury higher in the craniocervical junction and cervical spine. Standardized protocols and classification systems, such as the Pediatric Cervical Spine Clearance Working Group protocol and the AO Spine Injury and Subaxial Cervical Spine Injury Classifications, are valuable in triage as well as for assessing the need for operative versus nonoperative management. In general, operative approaches and principles are similar to those in adults, with modern instrumentation and fusion techniques achieving high rates of successful arthrodesis. Effective management and treatment of pediatric cervical spine injuries depends on early and accurate diagnosis, a thorough understanding of pediatric spinal anatomy, and a versatile surgical armamentarium.

Symptomatic Multi-Nodular Fourth Ventricular Choroid Plexus Papillary Fibrosis in the Context of Chiari II Malformation: Case Report and Literature Review

Introduction: Chiari II malformation (CM-II) is a congenital malformation characterized by the caudal displacement of the cerebellar tonsils, inferior cerebellar vermis, and fourth ventricle through the foramen magnum. Although rare, the association between CM-II and the development of a variety of mass lesions within the fourth ventricle and craniocervical junction has been described in the literature. Case Presentation: We present the case of a 9-year-old boy with a history of mid-lumbar myelomeningocele, CM-II, and ventriculoperitoneal shunt-dependent hydrocephalus who was discovered to have a syringomyelia and numerous spherical/ovoid masses within the caudal fourth ventricle and dorsal cervicomedullary subarachnoid space on a surveillance brain MRI. On questioning, the patient endorsed a longstanding history of poor bilateral hand dexterity and grip strength. After further imaging workup, the patient underwent suboccipital craniectomy and C1 laminectomy for resection of the mass lesions arising from the fourth ventricular choroid plexus (CP) and performance of an expansile pericranial duraplasty. The patient tolerated surgery well and had progressive improvement in hand dexterity/strength as well as radiographic improvement in the cervical cord syrinx after surgery. Pathologic analysis of the resected mass lesions demonstrated the lesions to be predominantly characterized by dense nodular fibrosis of the CP stromal cores which we are describing as choroid plexus papillary fibrosis. A minority of the lesional stromal cores were noted to be edematous, imparting a more “reticular” appearance. There were no features to suggest a neoplastic or infectious process. Conclusion: This combination of dysplastic/reactive CP histologic findings has not been previously reported in an extramedullary location. The unique pathology of this patient’s CP lesions will be discussed, and previously reported fourth ventricular mass lesions seen in association with CM-II will be reviewed.

Dural arteriovenous fistulas at the craniocervical junction: a systematic review and meta-analysis.

The management for craniocervical junction dural arteriovenous fistulas (CCJ-DAVFs) remains controversial and clinically challenging. We systemically summarized the clinical and angiographic outcomes of microsurgery, embolization, and conservative management. Relevant articles were retrieved from PubMed, Scopus, Web of Science, and Cochrane, following PRISMA guidelines. A systematic review and meta-analysis were conducted on the clinical characteristics, management approaches, and clinical and angiographic outcomes. We included 13 articles (166 patients). The weighted mean age was 58.9 years (95%CI: 53.2-64.5), 58.8 years (95%CI: 48.4-69.2), and 63.8 years (95%CI: 60.1-67.5), in microsurgery, embolization, and conservative groups respectively, with an overall male sex predominance (microsurgery [n = 51/77, 66.2%], embolization [n = 44/56, 78.6%], and conservative management [n = 6/8, 75.0%]). Patients were managed with microsurgery (n = 80/172, 46.5%), embolization (n = 79/172, 45.9%), and conservative treatment (n = 13/172, 7.6%). Foramen magnum was the most common location (microsurgery [n = 34/77, 44.2%], embolization [n = 31/56, 55.4%], and conservative treatment [n = 3/8, 37.5%]). Vertebral artery was the primary feeder (microsurgery [n = 58/84, 69.1%], embolization [n = 41/86, 47.6%], and conservative treatment [n = 4/7, 57.1%]). Complete fistula obliteration rates were 74.1% (95%CI:52.3-88.2%) in the microsurgery group and 54.9% (95%CI:30.7-77.0%) in the embolization group. Complications rates were 16.2% (95%CI:6.7-34.5%) in the embolization group, 11.6% (95%CI:3.8-30.4%) in the microsurgery group, and 7.7% (95%CI:1.1-39.1%) in the conservative group. Different rates of good clinical outcomes were observed [microsurgery: 66.4% (95%CI:48.1-80.8%), embolization: 51.9% (95%CI:30.8-72.4%), and conservative: 11.6% (95%CI:4.4-27.4%)]. In patients with CCJ-DAVFs, each management approach has its own merits based on the fistula and patient characteristics.

C0-C1 joint injection: Anatomical, clinical and technical review

BackgroundCervicogenic headaches (CGH) are proven clinical entities. The prevalence of CGH arising from the atlanto-occipital (AO) joint is unknown. The best evidence for treatment of CGH is for third occipital nerve radiofrequency neurotomy. Treatment of CGH includes intra-articular injections into upper cervical spine joints. ObjectiveTo perform a review of the anatomy and clinical presentation of AO joint (AOJ) pain referral as well as a technical description to safely access the AOJ. MethodsA literature review was performed to explore the intricacies of the cranio-cervical junction (CCJ) with a focus on the relation between the AOJ and vascular anatomy. Our technical approach is described with complementary images. ResultsThe AOJ lies anterior to a venous sinus and slightly superior to the horizontally oriented vertebral artery crossing the joint line. ConclusionThe authors propose a modified superior needle trajectory that seeks to avoid these vascular structures and to access the AOJ safely.

Significant individual variation in cardiac-cycle-linked cerebrospinal fluid production following subarachnoid hemorrhage

BackgroundSpontaneous subarachnoid hemorrhage (SAH) often results in altered cerebrospinal fluid (CSF) flow and secondary hydrocephalus, yet the mechanisms behind these phenomena remain poorly understood. This study aimed to elucidate the impact of SAH on individual CSF flow patterns and their association with secondary hydrocephalus.MethodsIn patients who had experienced SAH, changes in CSF flow were assessed using cardiac-gated phase-contrast magnetic resonance imaging (PC-MRI) at the Sylvian aqueduct and cranio-cervical junction (CCJ). Within these regions of interest, volumetric CSF flow was determined for every pixel and net CSF flow volume and direction calculated. The presence of acute or chronic hydrocephalus was deemed from ventriculomegaly and need of CSF diversion. For comparison, we included healthy subjects and patients examined for different CSF diseases.ResultsTwenty-four SAH patients were enrolled, revealing a heterogeneous array of CSF flow alterations at the Sylvian aqueduct. The cardiac-cycle-linked CSF net flow in Sylvian aqueduct differed from the traditional figures of ventricular CSF production about 0.30–0.40 mL/min. In 15 out of 24 patients (62.5%), net CSF flow was retrograde from the fourth to the third and lateral ventricles, while it was upward at the cranio-cervical junction in 2 out of 2 patients (100%). The diverse CSF flow metrics did not distinguish between individuals with acute or chronic secondary hydrocephalus. In comparison, 4/4 healthy subjects showed antegrade net CSF flow in the Sylvian aqueduct and net upward CSF flow in CCJ. These net CSF flow measures also showed interindividual variability among other patients with CSF diseases.ConclusionsThere is considerable inter-individual variation in net CSF flow rates following SAH. Net CSF flow in the Sylvian aqueduct differs markedly from the traditional ventricular CSF production rates of 0.30–0.40 mL/min in SAH patients, but less so in healthy subjects. Furthermore, the cardiac-cycle-linked net CSF flow rates in Sylvian aqueduct and CCJ suggest an important role of extra-ventricular CSF production.

Delayed Diagnosis of a Ruptured Distal Posterior Inferior Cerebellar Artery (PICA) Dissecting Aneurysm Presenting as Craniocervical Junction and Spinal Subdural Hematoma

Delayed Diagnosis of a Ruptured Distal Posterior Inferior Cerebellar Artery (PICA) Dissecting Aneurysm Presenting as Craniocervical Junction and Spinal Subdural Hematoma

Desmoid fibromatosis following surgery of an intradural spinal lipoma in a young cat

BackgroundIntradural lipomas have been previously reported in individuals with spinal dysraphism; however, they have not been reported in cats with an intact spinal canal. Desmoid tumors are a rare finding in veterinary medicine, and there is no prior description of these tumors invading the spinal cord. Furthermore, the etiopathogenesis remains debated, with trauma, such as surgical intervention of an intradural structure, potentially contributing to its development.Case descriptionA 10-month-old domestic shorthair cat was presented initially with progressive proprioceptive ataxia. The MRI identified an intradural compressive lesion at the cranio-cervical junction, confirmed as a lipoma by histopathology. Despite surgical removal, postoperative complications led to the cat's euthanasia. Postmortem examination revealed invasion of a desmoid tumor at the surgical site.ConclusionsThis case highlights the rarity of intradural lipomas in this location and the unusual complication of desmoid tumor invasion. It underscores the need for further research into the underlying mechanisms and potential diagnostic and therapeutic strategies for similar cases and suggests that these findings may be added to the list of potential post-surgical complications.

Differentiating the Structural and Functional Instability of the Craniocervical Junction.

This paper presents the anatomical and biomechanical aspects of chronic instability of the craniocervical junction (CCJ) with a discussion on clinical diagnostics based on mobility tests and provocative tests related to ligamentous system injuries, as well as radiological criteria for CCJ instability. In addition to the structural instability of the CCJ, the hypothesis of its functional form resulting from cervical proprioceptive system (CPS) damage is discussed. Clinical and neurophysiological studies have shown that functional disorders or organic changes in the CPS cause symptoms similar to those of vestibular system diseases: dizziness, nystagmus, and balance disorders. The underlying cause of the functional form of CCJ instability may be the increased activity of mechanoreceptors, leading to "informational noise" which causes vestibular system disorientation. Due to the disharmony of mutual stimulation and the inhibition of impulses between the centers controlling eye movements, the cerebellum, spinal motoneurons, and the vestibular system, inadequate vestibulospinal and vestibulo-ocular reactions occur, manifesting as postural instability, dizziness, and nystagmus. The hyperactivity of craniocervical mechanoreceptors also leads to disturbances in the reflex regulation of postural muscle tone, manifesting as "general instability". Understanding this form of CCJ instability as a distinct clinical entity is important both diagnostically and therapeutically as it requires different management strategies compared to true instability. Chronic CCJ instability significantly impacts the quality of life (QOL) of affected patients, contributing to chronic pain, psychological distress, and functional impairments. Addressing both structural and functional instability is essential for improving patient outcomes and enhancing their overall QOL.

Upper cervical epidural abscess with emphasis on diabetes as a risk factor: a case report

BackgroundAn upper cervical spine epidural abscess (UCEA) is an epidural abscess that develops in the area between the occiput and the second cervical spine (axis). It is a rare diagnosis that carries the risk of instability of the atlantoaxial joint, and its management is not well-defined. It is known that the skin is the most common source of infection, and that diabetes mellitus (DM) is the most frequently reported risk factor. In this case, we present a patient diagnosed with UCEA, who achieved full neurological recovery postoperatively despite having neurological deficits for over five days prior to surgery.Case presentationWe report the case of a 56-year-old male patient with no history of any prior medical conditions, who presented with headache, neck pain, and weakness of the left side. The weakness started approximately three days prior to his presentation. His initial work up revealed hyperglycemia and elevated HbA1c of 86 mmol/mol (10%). Magnetic resonance imaging (MRI) of the cervical spine revealed spondylitis of the C2 spine with an abscess at the craniocervical junction. He underwent a two-staged surgical approach: decompression and stabilisation. The patient achieved full motor recovery approximately three months postoperatively.ConclusionsWe recommend screening for DM when a spinal epidural abscess (SEA) is diagnosed without readily identifiable risk factors. The optimal management in most SEA cases is surgical, which is particularly true for UCEA because of the risk of atlantoaxial joint instability. Full neurological recovery is possible even when the patient has been having deficits for more than five days.

Surgical Treatment of Craniocervical Junction Tumors: Neurosurgery Department Experience of “Hôpital Principal De Dakar”

Introduction: Craniocervical tumors are uncommon but represent a medical emergency for diagnosis and treatment. Their approaches require of course surgical expertise in addition to adapted technical platform. In light of the limited resources available in our practice, we consequently made the decision to share our experience with the surgical treatment of this pathology. Patients and method: We performed a retrospective analysis on eight observations of patients treated in the neurosurgery department of “Hôpital Principal de Dakar” between July 2015 and December 2022 for progressive tumor spinal cord compression at the craniocervical junction. Results: We observed a 10% frequency, a mean age of 39.25 years, and extremes between 8 and 62 years. There was a 0.6 sex ratio. The most common risk factor was type I neurofibromatosis, and one case of Von Hippel-Lindau disease. All of our patients had pyramidal syndrome. Overall, there were 2 tumors with posterolateral extradural site and 4 tumors with extramedullary intradural location, including 2 posterolateral and 2 anterolateral. The location was intramedullary and cerebella-medullary in one case each. The posteromedial occipitocervical approach, which was employed on six patients, was the most utilized method. Five patients had total tumor resection, whereas three had partial resection. Two of our patients had postoperative complications: a worsening of motor deficit and a death following dependence on mechanical ventilation. We only received four histological confirmations for the anatomopathological samples. Our patients' evolution was positive over an average follow-up of 21 months, with neurological improvement and walking autonomy. Conclusion: Tumors affecting the craniocervical junction are still treated surgically. Despite the need for improvement in our working conditions, our results appear to be satisfactory.

Bipartition of the atlanto-occipital joint surfaces in a South African sample

BackgroundOne variation of the atlanto-occipital joint contains a groove or crest dividing the superior articulating facet of C1 and/or the corresponding occipital condyle. This study aimed to estimate the prevalence of bipartition of the facets associated with the atlanto-occipital joint and to determine the relationships between the corresponding joint surfaces, bilateral and unilateral facets as well as demographic factors in a South African sample. Materials and methodsData about shape and bipartition found on the superior articular facets of the atlas and the occipital condyles were collected from 109 skulls and atlases from the Pretoria Bone Collection, South Africa. Shape data was categorically classified according to existing criteria from literature. ResultsThe results revealed the occasional occurrence of a double facet at both the superior articular facet of the atlas (15.6 %), and the occipital condyle (7.34 %). Shape and facet number of the superior articulating facet and corresponding occipital condyle were significantly correlated. The prevalence of bipartition of neither the superior articular facets nor the occipital condyles were statistically significantly different between the left and right sides. Sex and age did not statistically significantly contribute to prevalence of bipartition in this population. However, population group statistically significantly contributed to prevalence of bipartition (p = 0.019), with the White South African sample having a much higher prevalence (88.24 % superior articulating facet, 100 % occipital condyle) of bipartition compared to the Black South African sample (11.76 % superior articular facet, 0 % occipital condyle). ConclusionAwareness of this joint variation and instances where it is more likely to occur may be valuable for neuro-vascular and orthopaedic surgeons when doing invasive treatments around the craniocervical junction, and chiropractors when assessing and treating patients.

Follow-Up Imaging in Angiography-Negative Spontaneous Subarachnoid Hemorrhage

BackgroundThe aim of this study was to assess the diagnostic yield of follow-up investigations in aneurysm negative SAH patients. Material and MethodsIn 109 (25%) of 435 patients with SAH and initial negative DSA, the diagnostic yield of repeat DSA and MRI of the brain and craniocervical junction was reviewed. ResultsOf the 109 patients with an initial negative DSA, 51 (47%) had perimesencephalic (PM), 54 (50%) had non-perimesencephalic (NPM) blood distribution, and 4 (3.7%) had CT-negative SAH. A delayed bleeding source was determined in 3 of 82 (3.7%) patients who underwent repeat DSA, and in 1/5 patients who underwent a third DSA. The bleeding patterns of these patients were all NPM (n=4). Repeat DSA did not identify a bleeding source in patients with PM-SAH. MRI of the brain and craniocervical junction after 2 days revealed a bleeding source in 1/105 patients (1%) in a CT-negative SAH. When all diagnostic modalities, including exploratory craniotomy and MRI of the spinal axis were considered, the rate of delayed diagnosis of the bleeding source was 6.4% (7/109). In addition to the bleeding pattern, patients with delayed diagnosis of the bleeding source were characterized by worse disease severity parameters, worse radiological grading scales, and more in-hospital complications than patients without delayed diagnosis of a bleeding source. ConclusionThe results of this study support the use of repeat DSA in patients with NPM-SAH, however, routine repeat DSA may not be indicated in PM-SAH patients. The routine use of MRI remains controversial.

Comprehensive comparative study ofChiari-like malformation inveterinary and human medicine.

This review aims toenrich our understanding ofChiari-like malformation (CLM) bycombining human and veterinary insights, and providing adetailed cross-species overview. CLM isadevelopmental abnormality characterised bycaudal displacement ofthe hindbrain into the foramen magnum due toan entire brain parenchymal shift caused byinsufficient skull volume. This malformation leads toaprogressive obstruction atthe craniocervical junction, which disrupts the normal cerebrospinal fluid flow, leading tosecondary syringomyelia. The clinical signs ofCLM and syringomyelia include phantom scratching, head tilt, head tremor, ataxia, tetraparesis, pain, muscle atrophy, and scoliosis ortorticollis. Magnetic resonance imaging remains the gold standard for diagnosing CLM, since itallows the visualisation ofabnormal findings such asthe caudal cerebellar herniation, caudal cerebellar compression from occipital dysplasia, and attenuated cerebrospinal fluid cisternae. Although various medical and surgical interventions, including foramen magnum decompression, can provide temporary symptomatic/clinical sign relief, current literature shows alack ofsustained long-term efficacy. Therefore, additional research isneeded toevaluate the long-term effects ofexisting treatment strategies and tocompare different techniques utilised inconjunction with foramen magnum decompression.

Endoscopy-assisted high cervical anterolateral retropharyngeal approach to clivus: a cadaveric study.

The surgical management of pathologies involving the clivus and craniocervical junction has always been considered a complex procedure because of the deeply located surgical targets and the surrounding complex neural and vascular anatomical structures. The most commonly used approaches to reach this area are the transnasal, transoral, and transcervical approaches. This approach was performed unilaterally on five cadaver heads and bilaterally on one cadaver head. We described a modified endoscope-assisted high cervical anterolateral retropharyngeal approach in which each stage of the procedure was demonstrated on human cadavers in a step-by-step manner using endoscopic camera views. This approach was broken down into nine steps. The neurovascular structures encountered at each step and their relationships with each other are demonstrated. The advantages and disadvantages of our modified approach were compared to the conventional transcervical, transoral, and endoscopic endonasal approaches.

Surgical resection of pediatric craniocervical junction Rosai-Dorfman histiocytosis-a case report and literature review.

Rosai-Dorfman disease (RDD) with craniocervical junction involvement is a rare clinical entity. We present herein a case of a pediatric patient with craniocervical junction RDD which was surgically treated. A 10-year-old female with a history of B-cell acute lymphoblastic leukemia (B-ALL) in remission and RDD presented with frontal migraine headaches. She previously had a right posterior chest wall lesion which was biopsy-proven RDD. She was found on imaging to have a dural-based right craniocervical junction lesion. Given her history of B-ALL, after a multidisciplinary discussion, the decision was made to proceed with resection with possible initiation of cobimetinib or clofarabine. The patient underwent a suboccipital craniotomy, C1 laminectomy, and resection of the dural-based lesion. Gross total resection was achieved, and histopathology confirmed the diagnosis of RDD. She was discharged home on postoperative day 4. No recurrence was seen on follow-up imaging at 3months. We conducted a systematic literature review examining all cases of pediatric intracranial RDD and all cases of craniocervical junction RDD. This represents, to the best of our knowledge, only the second case of pediatric craniocervical junction RDD. Although RDD is often self-limiting, medical treatment is often considered for intracranial disease, but tissue confirmation is necessary. Surgical resection provides histopathologic diagnosis and can sometimes serve as definitive treatment for a particular lesion.

Enlarging neurenteric cyst at the craniocervical junction with a fluid-fluid level on magnetic resonance imaging: illustrative case.

Neurenteric cysts are relatively rare benign congenital intracranial cystic lesions that enlarge rarely and very slowly. The authors present a case of an enlarging neurenteric cyst at the craniocervical junction with a fluid-fluid level on magnetic resonance imaging (MRI). A 34-year-old man with no significant medical history underwent head MRI to investigate mild headaches. An incidental cystic lesion, approximately 8 mm in diameter, was revealed at the craniocervical junction. Serial follow-up MRI showed cyst enlargement with a fluid-fluid level. Four years later, the cyst reached a size of 15 mm and was surgically removed. The cyst contained cloudy fluid with a high protein concentration, without any bleeding or tissue fragments. Pathological examination confirmed the diagnosis of a neurenteric cyst. The patient recovered well, was discharged home, and has remained recurrence free for 2 years. The growth dynamics of the relatively rapidly expanding neurenteric cyst at the craniocervical junction were monitored over time using MRI. This cyst exhibited the distinctive feature of a fluid-fluid level as it enlarged. Investigating the mechanisms underlying fluid-fluid level formation may offer novel insights into the pathogenesis of cyst enlargement. https://thejns.org/doi/10.3171/CASE24180.

Transient Decrease in Cerebrospinal Fluid Motion Is Related to Cough-Associated Headache in Chiari I Malformation

Short-lasting cough-associated Headache (CAH) in patients with Chiari I Malformation (CMI) is believed to be due to transient worsening of CSF flow obstruction at the foramen magnum. We assessed changes in CSF flow in response to coughing in CMI patients with CAH and compared to those without CAH and healthy participants (HP) using real-time MRI. Seventeen CMI patients (12 with CAH, 5 without CAH) and 6 HP were prospectively assessed using real-time pencil-beam imaging (PBI) MR sequence. A 64-mm length PBI cylinder was placed at the cranio-cervical junction. CSF stroke volume (SVCSF) was assessed during resting, post-coughing and relaxation phases via a 90-second scan. SVCSF was measured at six levels at 5-mm intervals between 10 and 35 mm below the foramen magnum. During each phase, SVCSF was compared between CMI with and without CAH and HP and corrected for multiple comparisons. At multiple consecutive levels, post-coughing SVCSF was significantly lower in CMI with CAH compared to both CMI without CAH and HP (p <0.05). No differences in post-coughing SVCSF were seen between CMI without CAH and HP. At rest or relaxation phase, no differences in SVCSF were seen between patients with and without CAH but minimal differences were seen between CMI with CAH and HP. A decrease in CSF flow after coughing in CMI patients with CAH supports the notion that CAH is caused by transient worsening of CSF flow obstruction at the foramen magnum.