Primary glioblastoma multiform (GBM) of the optic nerve and chiasma: A case report and systematic review of the literature.

Key Clinical Message: Primary GBM of the optic nerve and chiasma should be included in the differential diagnosis of progressive lesions despite initial treatment; clinicians should avoid delay in confirming the histology to initiate proper treatment and improve prognosis. Abstract: Primary GBM of the optic nerve or chiasma is very rare. The characteristics of this condition have not been well-described, which poses difficulties in establishing the correct diagnosis, affecting the treatment and the prognosis. We present a case of GBM of the optic chiasma diagnosed through an open biopsy at our centre. Following the PRISMA statement, we also conducted a systematic review after protocol registration in PROSPERO (CRD42021285855). We searched Medline and Embase through Ovid from inception until December 31, 2021. Two reviewers independently screened the studies. Studies were eligible for inclusion if they reported cases of primary GBM confined to the optic nerve or chiasma as the initial radiological diagnosis. A 77-year-old female was referred for progressive visual loss lasting 8 weeks. MRI revealed a suspected lesion in the left chiasma. The patient's vision deteriorated further despite initially diagnosing an inflammatory process and empirical treatment with corticosteroids. Subsequently, the patient underwent an open biopsy and surgical debulking. Histology, including epigenetic analysis, confirmed GBM grade IV. Radiochemotherapy was administered. The patient died 19 months after surgery. We identified 45 similar cases (22 female) reported in 35 studies between 1949 and 2020. The mean age of the cases was 61 (SD = 14.6). Most cases were misdiagnosed and mistreated accordingly, so there was a median delay of 8 weeks (IQR: 5-14 weeks) in obtaining histological confirmation of the diagnosis, delaying the initiation of appropriate treatment. Five cases became no treatment since the patients died shortly after the delayed histologic diagnosis. The Kaplan-Meier estimate indicated that most patients died within 20 months of presentation, with a 1-year survival rate of 50%, and untreated cases had very low survival rates compared to treated cases. Primary GBM of the optic nerve and chiasma is a rare condition primarily affecting adults. The rarity of this condition contributes to initial misdiagnosis, mistreatment, and delays in confirming the histology and initiating appropriate treatment. The prognosis remains poor, but treatment, including surgery and radiochemotherapy, improves survival.

Synthetically induced Arabidopsis thaliana autotetraploids provide insights into the analysis of meiotic mutants with altered crossover frequency.

Mutations affecting crossover (CO) frequency and distribution lead to the presence of univalents during meiosis, giving rise to aneuploid gametes and sterility. These mutations may have a different effect after chromosome doubling. The combination of altered ploidy and mutations could be potentially useful to gain new insights into the mechanisms and regulation of meiotic recombination; however, studies using autopolyploid meiotic mutants are scarce. Here, we have analyzed the cytogenetic consequences in colchicine-induced autotetraploids (colchiploids) from different Arabidopsis mutants with an altered CO frequency. We have found that there are three types of mutants: mutants in which chiasma frequency is doubled after chromosome duplication (zip4, mus81), as in the control; mutants in which polyploidy leads to a higher-than-expected increase in chiasma frequency (asy1, mer3, hei10, and mlh3); and mutants in which the rise in chiasma frequency produced by the presence of two extrachromosomal sets is less than doubled (msh5, fancm). In addition, the proportion of class I/class II COs varies after chromosome duplication in the control. The results obtained reveal the potential of colchiploid meiotic mutants for better understanding of the function of key proteins during plant meiosis. This is especially relevant considering that most crops are polyploids.

Objective Assessment of Visual Field Defects Caused by Optic Chiasm and Its Posterior Visual Pathway Injury.

OBJECTIVES: To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury. METHODS: Typical cases of visual field defects caused by injuries to the optic chiasm, optic tracts, optic radiations, and visual cortex were selected. Visual field examinations, visual evoked potential (VEP) and multifocal visual evolved potential (mfVEP) measurements, craniocerebral CT/MRI, and retinal optical coherence tomography (OCT) were performed, respectively, and the aforementioned visual electrophysiological and neuroimaging indicators were analyzed comprehensively. RESULTS: The electrophysiological manifestations of visual field defects caused by optic chiasm injuries were bitemporal hemianopsia mfVEP abnormalities. The visual field defects caused by optic tract, optic radiation, and visual cortex injuries were all manifested homonymous hemianopsia mfVEP abnormalities contralateral to the lesion. Mild relative afferent pupil disorder (RAPD) and characteristic optic nerve atrophy were observed in hemianopsia patients with optic tract injuries, but not in patients with optic radiation or visual cortex injuries. Neuroimaging could provide morphological evidence of damages to the optic chiasm and its posterior visual pathway. CONCLUSIONS: Visual field defects caused by optic chiasm, optic tract, optic radiation, and visual cortex injuries have their respective characteristics. The combined application of mfVEP and static visual field measurements, in combination with neuroimaging, can maximize the assessment of the location and degree of visual pathway damage, providing an effective scheme for the identification of such injuries.

MRI-Based Evaluation of the Flexor Digitorum Superficialis Anatomy: Investigating the Prevalence and Morphometry of the "Chiasma Antebrachii".

Recent dissection studies resulted in the introduction of the term "chiasma antebrachii", which represents an intersection of the flexor digitorum superficialis (FDS) tendons for digits 2 and 3 in the distal third of the forearm. This retrospective investigation aimed to provide an MRI-based morphologic analysis of the chiasma antebrachii. In 89 patients (41 women, 39.3 ± 21.3 years), MRI examinations of the forearm (2010-2021) were reviewed by two radiologists, who evaluated all studies for the presence and length of the chiasma as well as its distance from the distal radioulnar and elbow joint. The chiasma antebrachii was identified in the distal third of the forearm in 88 patients (98.9%), while one intersection was located more proximally in the middle part. The chiasma had a median length of 28 mm (interquartile range: 24-35 mm). Its distances to the distal radioulnar and elbow joint were 16 mm (8-25 mm) and 215 mm (187-227 mm), respectively. T1-weighted post-contrast sequences were found to be superior to T2- or proton-density-weighted sequences in 71 cases (79.8%). To conclude, the chiasma antebrachii is part of the standard FDS anatomy. Knowledge of its morphology is important, e.g., in targeted injections of therapeutics or reconstructive surgery.

Recombination and sterility in inversion homo- and heterokaryotypes under a general counting model of chiasma interference.

It has long been known that the chiasmata are not independently distributed in most organisms, a phenomenon known as chiasma interference. In this paper, I suggest a model of chiasma interference that generalizes the Poisson model, the counting model, the Poisson-skip model, and the two-pathway counting model into a single framework, and use it to derive infinite series expressions for the sterility and recombination pattern probabilities in inversion homo- and heterokaryotypes, and a closed-form expression for the special case of the two-pathway counting model in homokaryotypes. I then use these expressions to perform maximum likelihood parameter estimations for recombination and tetrad data from various species. The results imply that the simpler counting models perform well compared to more complex ones, that interference works in a similar way in homo- and heterokaryotypes, and that the model fits well with data for the latter as well as the former. I also find evidence that the interference signal is broken by the centromere in some species, but not others, suggestions of negative interference in Aspergillus nidulans, and no consistent support for the theory that a second noninterfering chiasma pathway exists only in organisms that require double-strand break for synapsis. I suggest that the latter finding is at least partly due to issues involved in analyzing aggregate data from different experiments and individuals.

ASYNAPSIS 1 ensures crossover fidelity in polyploid wheat by promoting homologous recombination and suppressing non-homologous recombination.

During meiosis, the chromosome axes and synaptonemal complex mediate chromosome pairing and homologous recombination to maintain genomic stability and accurate chromosome segregation. In plants, ASYNAPSIS 1 (ASY1) is a key component of the chromosome axis that promotes inter-homolog recombination, synapsis and crossover formation. Here, the function of ASY1 has been cytologically characterized in a series of hypomorphic wheat mutants. In tetraploid wheat, asy1 hypomorphic mutants experience a reduction in chiasmata (crossovers) in a dosage-specific manner, resulting in failure to maintain crossover (CO) assurance. In mutants with only one functional copy of ASY1, distal chiasmata are maintained at the expense of proximal and interstitial chiasmata, indicating that ASY1 is required to promote chiasma formation away from the chromosome ends. Meiotic prophase I progression is delayed in asy1 hypomorphic mutants and is arrested in asy1 null mutants. In both tetraploid and hexaploid wheat, single asy1 mutants exhibit a high degree of ectopic recombination between multiple chromosomes at metaphase I. To explore the nature of the ectopic recombination, Triticum turgidum asy1b-2 was crossed with wheat-wild relative Aegilops variabilis. Homoeologous chiasmata increased 3.75-fold in Ttasy1b-2/Ae. variabilis compared to wild type/Ae. variabilis, indicating that ASY1 suppresses chiasma formation between divergent, but related chromosomes. These data suggest that ASY1 promotes recombination along the chromosome arms of homologous chromosomes whilst suppressing recombination between non-homologous chromosomes. Therefore, asy1 mutants could be utilized to increase recombination between wheat wild relatives and elite varieties for expediting introgression of important agronomic traits.

Isolated Flexor Digitorum Profundus Injuries in Flexor Zone II of the Hand: A Report of Five Cases.

Injuries of the hand's flexor tendons carry a poor prognosis, mainly if they are in zone II (also called 'the critical zone' or 'no man's land'). The superficial tendon in this zone ends by bifurcating and attaching to the sides of the middle phalanx, exposing the deep tendon that attaches to the distal phalanx. Thus, trauma to this zone may result in a complete cut to the deep tendon while the superficial one remains intact. The lacerated tendon, in turn, would be retracted proximally to the palm making it difficult to be found during wound exploration. The complex anatomy of the hand, particularly that of the flexor zones, may contribute to the misdiagnosis of a tendon injury. We report five cases of an isolated cut of the flexor digitorum profundus (FDP) tendon after traumatic injury to the flexor zone II of the hand. The mechanism of injury of each case is reported together with a clinical approach that guides ED physicians toward diagnosing flexor tendon injuries in hand. In cut wounds involving the flexor zone II of the hand, it should be not surprising to find that the deep tendon (FDP) is completely lacerated without an injury to the superficial one (FDS). Therefore, we conclude that a systematic examination approach for traumatic hand injuries is essential to ensure the proper assessment. Understanding the mechanism of injury, performing a systemic examination approach, and having basic anatomical knowledge of flexor tendons of the hand are essential to identifying tendon injuries, anticipating complications, and providing adequate healthcare.

Old name, new face: A systematic analysis of flexor digitorum superficialis muscle with "chiasma antebrachii".

The gross anatomy of the forearm flexors, particularly that of the flexor digitorum superficialis (FDS) muscle, has been described and graphically illustrated in several anatomical books and atlases starting in the middle of the century before last. However, in anatomical dissection studies as well as in clinical-anatomical courses training muscle-specific targeted injections due to movement disorders such as dystonia or spasticity, it has become apparent that there is a need for a closer investigation of the complex construction of the FDS muscle. To this end, we studied the structure of the muscle bellies and tendons of FDS on 46 human body donates that have been used either in our dissection or clinical-anatomical training courses. With this, we demonstrate here the topographical configuration of the individual muscle belly for each of digits 2 through 5 and the exact paths of their tendons until their passing through the carpal tunnel. Furthermore, we demonstrate the presence of a chiasm of the FDS tendons for the digits 2 and 3, approximately 3-4 cm proximal of the carpal tunnel. Thus, we introduce herewith the terminology "chiasma antebrachii". These findings were confirmed in situ by imaging of fixed human body donates via MRI and corroborated by MRI and ultrasound imaging in two volunteers. Taken together, the present findings enable an updated understanding of the complex organization of the heads, bellies, and tendons of FDS that is relevant not only for anatomical teaching but also clinical interventions.

Cytogenetic Analysis of the Bimodal Karyotype of the Common European Adder, Vipera berus (Viperidae).

Vipera berus is the species with the largest range of snakes on Earth and one of the largest among reptiles in general. It is also the only snake species found in the Arctic Circle. Vipera berus is the most involved species of the genus Vipera in the process of interspecific hybridization in nature. The taxonomy of the genus Vipera is based on molecular markers and morphology and requires clarification using SC-karyotyping. This work is a detailed comparative study of the somatic and meiotic karyotypes of V. berus, with special attention to DNA and protein markers associated with synaptonemal complexes. The karyotype of V. berus is a remarkable example of a bimodal karyotype containing both 16 large macrochromosomes and 20 microchromosomes. We traced the stages of the asynchronous assembly of both types of bivalents. The number of crossing-over sites per pachytene nucleus, the localization of the nucleolar organizer, and the unique heterochromatin block on the autosomal bivalent 6-an important marker-were determined. Our results show that the average number of crossing-over sites per pachytene nucleus is 49.5, and the number of MLH1 sites per bivalent 1 reached 11, which is comparable to several species of agamas.

Evaluation of Crossover Number, Distribution, and Interference Using Cytological Assays in Arabidopsis.

Meiosis involves the replication of nuclear chromosomes in a parent cell, followed by two successive nuclear divisions to produce haploid spores, which differentiate into the gametophyte generations that produce the egg and sperm in plants. Meiotic recombination or crossover (CO) is a hallmark of meiosis that allows shuffling of genetic information between homologous chromosomes (homologs), thereby giving rise to genetically diverse progeny cells and, ultimately, individuals in the progeny; this opens vast opportunities for genetic differentiation and hence speciation. Meiotic COs also ensure the formation of bivalents and fidelity of their equal segregation. Therefore, mechanisms that regulate meiotic recombination have been extensively studied in multiple species. Several approaches have been developed to observe or estimate the frequency of CO, in which CO can be visualized and analyzed cytologically by estimating the number of chiasma (plural chiasmata), a position where non-sister chromatids exchange genetic material between homologs. Furthermore, one CO event might influence the occurrence of another one nearby, along a chromosome; this is known as CO interference. Over the past decades, visualizing CO events and measuring CO interference have contributed greatly to our understanding of the regulatory mechanisms of meiotic recombination. Here, we describe protocols to estimate the number of chiasmata and CO interference in Arabidopsis using cytological methods involving chromosome spreads and immunostaining. Specifically, we describe how chromosome spreads can be used to estimate the number of chiasmata based on the conformations of metaphase I bivalents and provide a revised acid-based quick immunostaining assay that permits high-throughput and quantitative digital estimation of the relative distance between adjacent interference-sensitive CO foci at diakinesis. These methods can be easily established or modified, if necessary, for studying meiotic recombination in other plants and crops. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Estimation of the number of chiasmata per nucleus based on metaphase I bivalent conformations Basic Protocol 2: A chromosome spread-based immunostaining method for relative distance analysis of adjacent interference-sensitive CO foci at diakinesis in Arabidopsis meiocytes.

Information-processing speed in mildly disabled relapsing-remitting multiple sclerosis patients correlates with volumetry of optic chiasma and subcortical grey matter nuclei.

INTRODUCTION: Multiple sclerosis (MS) is an inflammatory demyelinating disease leading not only to physical disability but also to cognitive dysfunction. The aim of our study was to test cognitive functions of MS patients with mild relapsing-remitting form and to find out the relationship between cognitive functions and brain volumetry. METHODS: 52 patients (RRMSp) and 23 age-related healthy participants (CON) were enrolled. Mild disability was defined by mean EDSS 2.4 (≤ 4.0), and by median of disease duration 5.2 years. Cognitive status was tested using Single Digit Modality Test (SDMT). Brain volumetry was processed in FreeSurfer 2.0.0. RESULTS: RRMSp patients showed significantly lower SDMT score than CON. SDMT results correlated positively with volume of thalamus, putamen and nc. caudate, and negatively with optic chiasma volume. Compared with CON, RRMSp presented with significantly lower volume in left and right nc. accumbent, cuneus and insular GM, right putamen, total brain cortical grey matter (GM), white matters hypointensities, and 3rd ventricular widths. CONCLUSION: To our best knowledge, this is the first study that presents results showing a correlation of lower SDMT with higher optic chiasma volume, due to its subclinical chronic demyelination. We confirmed that GM atrophy is involved in cognitive functions in MS (Tab. 3, Fig. 2, Ref. 73).

A Unique Variation of Quadratus Plantae in Relation to the Tendons of the Midfoot.

A novel combination of variations involving the quadratus plantae muscle (QP) and its relationship to the flexor hallucis longus (FHL) tendon was observed unilaterally in the right foot of an 88-year-old female cadaver during routine dissection. The medial head of QP was observed inserting onto the tendon of FHL rather than the tendon of flexor digitorum longus (FDL), while also contributing to an anomalous tendinous slip to the second digit in conjunction with the tendon of FHL. The tendon of FHL also gave off a slip to the third digit. Both tendinous slips attached distally to the digital tendons of FDL. Lastly, the lateral head of QP inserted onto the tendinous slip from FHL to the third digit. Ninety-five additional feet were assessed for these variations, but none were observed. This combination of variations expands upon the proposed actions of QP in the literature. Furthermore, connections between the tendons of the midfoot are of clinical significance for harvesting tendon grafts.

A Case of Suprasellar, Intrasellar, and Infrasellar Meningioma Presenting as a Visual Field Defect in an Obese Female.

Bitemporal hemianopia is the most common visual field defect encountered in suprasellar meningiomas compressing the optic chiasma and its vascular supply. It is hard to distinguish between meningioma and tumors that arise from suprasellar, intrasellar, and infrasellar extensions. Clinical findings, hormonal levels, and radiological findings could help in labeling it as meningioma. A 53-year-old obese woman with a history of blurred vision more in the right eye, loss of smell, and a headache was diagnosed with meningioma having suprasellar, intrasellar, and infrasellar extension on neuroimaging. She developed bitemporal hemianopia, which gradually worsened over the course of six months with concomitant headaches and dizziness that was treated with analgesics leading to a delayed diagnosis. As she was symptomatic, it was decided to resect her tumor. The patient underwent an endoscopic transsphenoidal approach for tumor resection. Successful excision of the tumor was accomplished. Postoperatively on further evaluation, the patient's anosmia and the visual deficit were resolved. This instance shows that meningioma located in the sella can cause symptoms like anosmia and visual field loss, which should not be neglected. It also underlines the significance of visual field evaluation on a regular basis as this might predict radiological and symptomatic progression.

Comparative Evaluation of Two SD-OCT Macular Parameters (GCC, GCL) and RNFL in Chiasmal Compression.

Purpose: To evaluate the relationship between different macular thickness parameters analyzed by SD-OCT and the central visual field (VF) evaluated with automated kinetic perimetry in a cohort of patients with pituitary tumors. Methods: Data from patients with pituitary adenoma treated at Reims University Hospital between October 1st, 2017, and May 31st, 2018 were collected. All patients underwent an automated kinetic perimetry and a SD-OCT to map the ganglion cell complex (GCC), the ganglion cell layer (GCL) thickness and the retinal nerve fiber layer (RNFL) using devices from two different manufacturers. Univariate and multivariate analysis were used to evaluate the correlation between the area of central VF in square degrees (deg2) and the SD-OCT parameters (µm). Results: Eighty-eight eyes were included in the analysis. All the thickness parameters measured in SD-OCT decreased with the visual field alteration. The best correlation was observed between superior thickness parameters (GCC, GCL) and the inferior central visual field. The most pertinent predictive factors for visual field loss were the inferior central GCL and the nasal RNFL (both AUC=0.775) with a sensitivity respectively of 86% and 70%. Conclusion: This study suggests that both GCC, GCL thickness parameters could be reliable predictors of central visual field impairment in patients with pituitary tumors. There was no significative difference between both devices.

Evaluation of optic nerve diameters in individuals with neurofibromatosis and comparison of normative values in different pediatric age groups.

AIM: Our study aimed to report the normative values for optic nerve diameter in different age groups in MR imaging (MRI) in the pediatric population and to find a cut-off value for diagnosis in different age groups to be used for the diagnosis of optic glioma in patients with Neurofibromatosis 1(NF1). MATERIALS-METHODS: Orbital MRI obtained from 2011 to 2021 for children with and without NF1 were reviewed. Patients were divided into three groups: NF1 with glioma (group 1, n = 38), NF1 without glioma (group 2, n = 57), and healthy controls (group 3, n = 295). Two radiologists assessed diameter and tortuosity using validated criteria. The optic nerve measurements were obtained by two radiologists in two plans (axial and coronal sections) at five locations; retroocular, midsegment, and prechiasmatic segment on axial plane and retroocular segment and chiasmatic on coronal plane. RESULTS: Optic nerves were divided into 4 age groups: 0-2 years, 2-6 years, 6-12 years, and 12-18 years. It was observed that optic nerve diameters increased with age in healthy individuals. In subjects in groups 1 and 2, the mean diameter of the optic nerve was significantly greater at all locations compared with control individuals. Tortuosity scores were significantly associated in NF1 subjects with optic glioma than in NF1 subjects without optic glioma. CONCLUSION: We present the normative values obtained by measuring optic nerve diameters in pediatric populations (0-18 years) on MRI of our center. A rapid increase in optic nerve diameter was observed in the first 6 years of life, followed by a slower increase. Quantitative reference values for optic nerve diameter will benefit the development of objective diagnostic criteria for optic nerve gliomas (ONGs) secondary to NF1.

Awake Microsurgical Resection for Optochiasmatic Cavernous Malformation.

Cavernous malformations (CM) affect approximately 0.5% of the population, with only a limited portion being located in the optic nerve and chiasma. The clinical presentation is determined by their locations. In the optochiasmatic CM, the acute visual disturbance is the most common presentation. Chronically, many show a progressive visual loss, chronic headache, and pituitary disturbances. The differential diagnosis includes optic glioma, arteriovenous malformations, aneurysm, craniopharyngioma, pituitary apoplexy, and inflammatory conditions. In Video 1, we present the case of a 39-year-old woman with a history of a hemorrhagic optochiasmatic cavernoma in 2016, who started using propranolol to reduce the lesion and symptoms of visual loss. Moreover, the first microsurgical resection of the cavernoma and evacuation of the hematoma were performed in the same year. Owing to evolvement from a partial to a total vision loss in the left eye and presentation of new symptoms in the right eye, the patient underwent microsurgical resection. The surgery was performed sequentially. An awake craniotomy was performed to monitor the chiasma and right optic nerve. The postoperative magnetic resonance imaging showed complete resection of the CM, and the patient fully recovered. The patient signed the institutional consent form, stating that he or she accepts the procedure and allows the use of his or her images and videos for any type of medical publications in conferences and/or scientific articles.

[Neuro-computational approaches for objective assessment of visual function]. / Neurocomputationelle Ansätze zur objektiven Funktionsüberprüfung des Sehens.

BACKGROUND: Retinal pathologies affect the structure and function of post-retinal visual pathways. These post-retinal alterations bear the potential to obstruct the aim of innovative retinal treatment to restore visual function. OBJECTIVE: Current developments in the field of neuroimaging and the associated neurocomputational approaches enable a detailed assessment of this interrelationship. As a consequence, they open up the possibility to anticipate the success of treatment. METHODS: This review article demonstrates how innovations particularly in magnetic resonance imaging (MRI)-based anatomical, functional, and diffusion imaging can guide visual pathway assessments that are relevant for ophthalmological applications. RESULTS: Specific examples of retinal and visual pathway pathologies in the context of a detailed analysis of the visual pathway are described. CONCLUSION: A concept is introduced of how to translate the meaningful but technically and computationally challenging neuroimaging procedures into a clinical setting in order to effectively connect these procedures to innovative treatment approaches.

Chiasmata and the kinetochore component Dam1 are crucial for elimination of erroneous chromosome attachments and centromere oscillation at meiosis I.

Establishment of proper chromosome attachments to the spindle requires elimination of erroneous attachments, but the mechanism of this process is not fully understood. During meiosis I, sister chromatids attach to the same spindle pole (mono-oriented attachment), whereas homologous chromosomes attach to opposite poles (bi-oriented attachment), resulting in homologous chromosome segregation. Here, we show that chiasmata that link homologous chromosomes and kinetochore component Dam1 are crucial for elimination of erroneous attachments and oscillation of centromeres between the spindle poles at meiosis I in fission yeast. In chiasma-forming cells, Mad2 and Aurora B kinase, which provides time for attachment correction and destabilizes erroneous attachments, respectively, caused elimination of bi-oriented attachments of sister chromatids, whereas in chiasma-lacking cells, they caused elimination of mono-oriented attachments. In chiasma-forming cells, in addition, homologous centromere oscillation was coordinated. Furthermore, Dam1 contributed to attachment elimination in both chiasma-forming and chiasma-lacking cells, and drove centromere oscillation. These results demonstrate that chiasmata alter attachment correction patterns by enabling error correction factors to eliminate bi-oriented attachment of sister chromatids, and suggest that Dam1 induces elimination of erroneous attachments. The coincidental contribution of chiasmata and Dam1 to centromere oscillation also suggests a potential link between centromere oscillation and attachment elimination.

Ultrasonographic test for detecting the chiasma plantare formation between the flexor hallucis longus and flexor digitorum longus.

PURPOSE: Flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendons are frequently used in surgery. Therefore, it is necessary to evaluate the chiasma plantare formation preoperatively. The development of ultrasonography (US) may help the chiasma plantare formation evaluation. The purpose of this study is to prove the usefulness of the US method using cadavers. METHODS: Eleven cases (twenty-two ankles) were obtained from Asian adult cadavers. At first, we evaluated and compared the chiasma plantare formation using US. Later, we evaluated that using the findings after dissection as type A (connection from FHL to FDL of the second toe), type B (connection from FHL to the second and third toes), type C (connection from FHL to the second through fourth toes), or type D (connection from FHL to all lesser toes). RESULTS: Chiasma plantare formation was classified as types A and B in fifteen and seven ankles, respectively. After dissection, chiasma plantare formation was classified as types A, B, and C in fourteen, six, and two ankles, respectively. Therefore, there was an 86% similarity between the two methods. CONCLUSIONS: Chiasma plantare formation can be reliably and noninvasively evaluated using US. This may be useful for preoperative rehabilitation or surgical procedure planning.