DOCSLIB.ORG

Halo-Gravity Traction for the Treatment of Pediatric Cervical Spine Disorders Bram P

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Halo-Gravity Traction for the Treatment of Pediatric Cervical Spine Disorders Bram P CLINICAL ARTICLE J Neurosurg Pediatr 25:384–393, 2020 Halo-gravity traction for the treatment of pediatric cervical spine disorders Bram P. Verhofste, MD,1,2 Michael P. Glotzbecker, MD,3,4 Craig M. Birch, MD,1,2 Nora P. O’Neill, BA,1,2 and Daniel J. Hedequist, MD1,2 1Department of Orthopaedic Surgery, Boston Children’s Hospital; 2Harvard Medical School, Boston, Massachusetts; 3Department of Orthopaedic Surgery, University Hospitals Cleveland Medical Center; and 4Department of Orthopaedic Surgery, Rainbow Babies and Children’s Hospital, Cleveland, Ohio OBJECTIVE Halo-gravity traction (HGT) is an effective and safe method for gradual correction of severe cervical defor- mities in adults. However, the literature is limited on the use of HGT for cervical spine deformities that develop in children. The objective of the present study was to evaluate the safety and efficacy of HGT for pediatric cervical spine deformities. METHODS Twenty-eight patients (18 females) whose mean age was 11.3 ± 5.58 years (range 2–24.9 years) underwent HGT. Common indications included kyphosis (n = 12), rotatory subluxation (n = 7), and basilar invagination (n = 6). Three children (11%) received traction to treat severe occipitocervical instability. For these 3 patients, traction combined with a halo vest, with bars attached rigidly to the vest, but with the ability to slide through the connections to the halo crown, was used to guide the corrective forces and moments in a specific and controlled manner. Patients ambulated with a wheelchair or halo walker under constant traction. Imaging was done before and during traction to evaluate traction ef- ficacy. The modified Clavien-Dindo-Sink classification was used to categorize complications. RESULTS The mean duration of HGT was 25 days (IQR 13–29 days), and the mean traction was 29% ± 13.0% of body weight (IQR 19%–40% of body weight). The mean kyphosis improved from 91° ± 20.7° (range 64°–122°) to 56° ± 17.6° (range 32°–96°) during traction and corresponded to a mean percentage kyphosis correction of 38% ± 13.8% (range 21%–57%). Twenty-five patients (89%) underwent surgical stabilization, and 3 patients (11%) had rotatory subluxation that was adequately reduced by traction and were treated with a halo vest as their definitive treatment. The mean hospi- tal stay was 35 days (IQR 17–43 days). Nine complications (32%) occurred: 8 grade I complications (28%), including 4 cases of superficial pin-site infec- tion (14%) and 4 cases of transient paresthesia (14%). One grade II complication (4%) was seen in a child with Down syndrome and a preexisting neurological deficit; this patient developed flaccid paralysis that rapidly resolved with weight removal. Six cases (21%) of temporary neck discomfort occurred as a sequela of a preexisting condition and resolved without treatment within 24–48 hours. CONCLUSIONS HGT in children is safe and effective for the gradual correction of cervical kyphosis, atlantoaxial sub- luxation, basilar invagination, and os odontoideum. Cervical traction is an additional tool for the pediatric spine surgeon if uncertainties exist that the spinal alignment required for internal fixation and deformity correction can be safely achieved surgically. Common complications included grade I complications such as superficial pin-site infections and transient paresthesias. Halo vest gravity traction may be warranted in patients with baseline neurological deficits and severe oc- cipitocervical instability to reduce the chance of catastrophic movement. https://thejns.org/doi/abs/10.3171/2019.10.PEDS19513 KEYWORDS pediatric; children; cervical spine; halo-gravity traction; halo vest; efficacy; complications; adverse events; modified Clavien-Dindo-Sink classification TAGNARA popularized halo-gravity traction (HGT) in nal alignment in an attempt to reduce the amount of force 1971 as a method to use the natural force of gravity or surgical exposure required for the stabilization of severe to counteract pathological forces causing severe tho- spinal deformities and to decrease the risk of perioperative racicS scoliosis, kyphosis, or kyphoscoliosis.26,27 Traction neurological deficits.1,3–5, 15, 22, 25, 27,30 A halo crown with 4–8 causes soft-tissue relaxation that gradually improves spi- pins is placed in the operating room and stepwise distrac- ABBREVIATIONS AE = adverse event; ARS = atlantoaxial rotatory subluxation; BW = body weight; HGT = halo-gravity traction; HVGT = halo-vest-gravity traction; IONM = intraoperative neuromonitoring; LOS = length of stay; NF1 = neurofibromatosis type 1; SAC = space available for the spinal cord; SCC = spinal cord compression. SUBMITTED September 4, 2019. ACCEPTED October 28, 2019. INCLUDE WHEN CITING Published online December 27, 2019; DOI: 10.3171/2019.10.PEDS19513. 384 J Neurosurg Pediatr Volume 25 • April 2020 ©AANS 2020, except where prohibited by US copyright law Unauthenticated | Downloaded 10/01/21 11:45 AM UTC Verhofste et al. tion is performed until 30%–50% of body weight (BW) is national patients are treated at our institution. These cases reached.3,15,19,22,30 Weight in this range is usually tolerated were included in the analysis, however, to accurately rep- well, and immediate mobilization is allowed with a wheel- resent the cervical spine population treated at the pediatric chair or halo walker.3,15 tertiary referral centers that perform HGT. These patients Daily pin-site care and neurological evaluation are had complete records of their in-hospital HGT admission, required and can prevent most traction-related compli- which was the objective of the study. cations. Mild complications such as cervical discomfort, pin-site infections, and pin loosening are common and are Radiographic Parameters easily managed with muscle relaxants, antibiotics, and pin 3,9,19,21,22,30 Serial radiographs were used to evaluate kyphosis be- tightening. More severe complications such as fore HGT, during traction, postoperatively, and at the latest cranial nerve dysfunction, subdural abscesses, vertebral follow-up. Absolute kyphosis correction was calculated as artery aneurysms, and paraplegia are also rarely report- 4,9,10,14,31 follows: [pre-HGT − in-traction], and % kyphosis correc- ed. tion as: [(absolute correction/pre-HGT) × 100%]. A meth- Good outcomes of preoperative HGT are reported in od was developed to maintain traction during CT scan- adults with severe basilar invagination, cervical kyphosis, ning. The severity of basilar invagination was assessed on or irreducible atlantoaxial subluxation in which single- serial CT scans using McRae’s line, defined as a line con- stage realignment or instrumentation may be problemat- 6 13,17,20,24,25,32 necting the inner foramen magnum (basion to opisthion). ic. Cervical traction reduces the difficulty of an- The distance from the tip of the odontoid process perpen- terior surgery in severely kyphotic patients and alleviates dicular to this line was evaluated before and during HGT. the need for transoral decompression in cases of complex Similarly, the space available for the spinal cord (SAC) craniocervical junction malformations. The literature on was used to measure the effect of traction in cases of os HGT for the management of cervical spine disorders that odontoideum. develop in children is limited to small case series that are often outdated, include adults, or utilize traction intra- and Complication Data postoperatively.1,10, 13, 14, 16, 18, 24, 28,31 To our knowledge, this is the largest series dedicated to evaluating the efficacy and All HGT-related adverse events (AEs) were recorded using the modified Clavien-Dindo-Sink classification safety of HGT for pediatric cervical spine disorders. 7 The goals of this retrospective case series were as fol- (grades I–V) for orthopedic complications. Superficial lows: 1) to describe the benefits and efficacy of HGT for pin-site infections or transient paresthesias were classi- the treatment of cervical spine disorders that develop in fied as grade I or as complications that did require a de- children; 2) to review the safety and complications using viation from routine care, had minimal clinical relevance, the modified Clavien-Dindo-Sink classification; and 3) to and were adequately treated with observation or minimal provide a protocol for HGT with recommendations from intervention (oral antibiotics, analgesics, or antipyretics). an experienced tertiary pediatric referral center. Grade II HGT-related complications included transient cranial nerve dysfunction, nerve palsies, or other tempo- rary neurological deficits that required a deviation from Methods HGT protocol (increased inpatient visits during hospital- A retrospective consecutive examination of children ization, close neurological monitoring, or weight removal). who underwent HGT during a 15-year period (2003–2018) Grades I and II are considered minor complications. was performed after IRB approval. All patients were Grade III–V complications are serious AEs classified treated at a single pediatric tertiary referral center (Boston as major complications. Subdural abscesses, cellulitis, or Children’s Hospital). Patients < 25 years of age diagnosed deep dermal infections were grade III complications that with occipitocervical or cervical instability, cervical ky- required surgical, interventional radiology, or endoscopic phosis, basilar invagination, atlantoaxial rotatory sublux- interventions, such as drainage, debridement, and intrave- ation (ARS), os odontoideum, or cervical arthritis with nous antibiotics. Grade
Load more

Recommended publications
  • Anterior Esthetic Crown-Lengthening Surgery: a Case Report
    C LINICAL P RACTICE Anterior Esthetic Crown-Lengthening Surgery: A Case Report • Jim Yuan Lai, BSc, DMD, MSc (Perio) • • Livia Silvestri, BSc, DDS, MSc (Perio) • • Bruno Girard, DMD, MSc (Perio) • Abstract The theoretical concepts underlying crown-lengthening surgery are reviewed, and a patient who underwent esthetic crown-lengthening surgery is described. An overview of the various indications and contraindications is presented. MeSH Key Words: case report; crown lengthening; periodontium/surgery © J Can Dent Assoc 2001; 67(10):600-3 This article has been peer reviewed. he appearance of the gingival tissues surrounding room for adequate crown preparation and reattachment of the teeth plays an important role in the esthetics of the epithelium and connective tissue.4 Furthermore, by T the anterior maxillary region of the mouth. altering the incisogingival length and mesiodistal width of Abnormalities in symmetry and contour can significantly the periodontal tissues in the anterior maxillary region, the affect the harmonious appearance of the natural or pros- crown-lengthening procedure can build a harmonious thetic dentition. As well nowadays, patients have a greater appearance and improve the symmetry of the tissues. desire for more esthetic results which may influence treat- Good communication between the restoring dentist and ment choice. the periodontist is important to achieve optimal results An ideal anterior appearance necessitates healthy and with crown-lengthening surgery, particularly in esthetically inflammation-free periodontal tissues. Garguilo1 described demanding cases. In addition to establishing the smile line, various components of the periodontium, giving mean the restoring dentist evaluates the anterior and posterior dimensions of 1.07 mm for the connective tissue, 0.97 mm occlusal planes for harmony and balance, as well as the for the epithelial attachment and 0.69 mm for the sulcus anterior and posterior gingival contours.
    [Show full text]
  • Human Anatomy and Physiology
    LECTURE NOTES For Nursing Students Human Anatomy and Physiology Nega Assefa Alemaya University Yosief Tsige Jimma University In collaboration with the Ethiopia Public Health Training Initiative, The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education 2003 Funded under USAID Cooperative Agreement No. 663-A-00-00-0358-00. Produced in collaboration with the Ethiopia Public Health Training Initiative, The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education. Important Guidelines for Printing and Photocopying Limited permission is granted free of charge to print or photocopy all pages of this publication for educational, not-for-profit use by health care workers, students or faculty. All copies must retain all author credits and copyright notices included in the original document. Under no circumstances is it permissible to sell or distribute on a commercial basis, or to claim authorship of, copies of material reproduced from this publication. ©2003 by Nega Assefa and Yosief Tsige All rights reserved. Except as expressly provided above, no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission of the author or authors. This material is intended for educational use only by practicing health care workers or students and faculty in a health care field. Human Anatomy and Physiology Preface There is a shortage in Ethiopia of teaching / learning material in the area of anatomy and physicalogy for nurses. The Carter Center EPHTI appreciating the problem and promoted the development of this lecture note that could help both the teachers and students.
    [Show full text]
  • Most Cited Publications in Cervical Spine Surgery
    Most Cited Publications in Cervical Spine Surgery Yu Chao Lee, Francis Brooks, Simon Sandler, Yun-Hom Yau, Michael Selby and Brian Freeman Int J Spine Surg 2017, 11 (3) doi: https://doi.org/10.14444/4019 http://ijssurgery.com/content/11/3/19 This information is current as of October 2, 2021. Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://ijssurgery.com/alerts The International Journal ofDownloaded Spine Surgery from http://ijssurgery.com/ by guest on October 2, 2021 2397 Waterbury Circle, Suite 1, Aurora, IL 60504, Phone: +1-630-375-1432 © 2017 ISASS. All Rights Reserved. Most Cited Publications in Cervical Spine Surgery Yu Chao Lee, Francis Brooks, Simon Sandler, Yun-Hom Yau, Michael Selby, Brian Freeman Royal Adelaide Hospital, Adelaide, Australia Abstract Purpose The purpose of this study is to perform a citation analysis on the most frequently cited articles in the topic of cervi- cal spine surgery and report on the top 100 most cited publication in this topic. Methods We used the Thomson Reuters Web of Science to search citations of all articles from 1945 to 2015 relevant to cer- vical spine surgery and ranked them according to the number of citations. The 100 most cited articles that matched the search criteria were further analyzed by number of citations, first author, journal, year of publication, country and institution of origin. Results The top 100 cited articles in the topic of cervical spine surgery were published from 1952-2011. The number of ci- tations ranged from 106 times for the 100th paper to 1206 times for the top paper.
    [Show full text]
  • Cervical Spine Considerations When Anesthetizing Patients with Down Syndrome Tara Hata, M.D.,* Michael M
    Ⅵ CLINICAL CONCEPTS AND COMMENTARY Richard B. Weiskopf, M.D., Editor Anesthesiology 2005; 102:680–5 © 2005 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Cervical Spine Considerations When Anesthetizing Patients with Down Syndrome Tara Hata, M.D.,* Michael M. Todd, M.D.† DOWN syndrome (DS) is the most common chromo- sion from the body of the vertebra. The dens passes somal disorder, occurring in 1 of every 600–800 births.1 cephalad immediately behind the anterior arch C1 and is It is characterized by mental retardation, as well as held in place by three ligaments (fig. 1). The transverse craniofacial, upper airway, cardiovascular, and gastroin- ligament (or the transverse component of the cruciate testinal anomalies. One manifestation of DS relevant to ligament) passes from side to side behind the odontoid anesthesiologists is upper cervical spine instability pro- and is anchored to the inside of the C1 ring. The atlan- duced by ligamentous laxity, skeletal anomalies, or both. todental ligament bridges the small space between the This instability can result in neurologic impairment, in- anterior aspect of the odontoid and the posterior aspect cluding quadriplegia. However, there are no evidence- of the anterior arch of C1 (this space is referred to as the based practical guidelines to aid anesthesiologists in car- anterior atlantodental interval [AADI]). The alar liga- ing for these patients. The risk of spinal cord injury ments extend from the dens upward and laterally to the during anesthesia is unknown, as are the preoperative occipital condyles, and the apical ligament extends from factors that might aid in accurately defining the risk in the tip of dens upward to the anterior margin of the specific patients.
    [Show full text]
  • Spinal Cord Injury (SCI) May Happen When You Are in an Accident, Fall, Or Have a Disease That Affects Your Spinal Cord
    uihc.org Introduction Spinal cord injury (SCI) may happen when you are in an accident, fall, or have a disease that affects your spinal cord. This book was written by health care providers who care for patients and their families as they deal with these injuries or conditions. We hope it teaches you about the injured spine and spinal cord, and answers your questions about what to expect in the days and months to come. Exact answers may not be known because the long-term effects of SCI can be hard to predict. Research is still being done to improve treatment and outcomes of SCI. Written by: Michele L. Wagner, RN, MSN, CNRN Department of Nursing APN, Neuroscience Janet A. Stewart, RN, BSN, ONC Department of Nursing, Orthopedics and Rehabilitation Karen M. Stenger, RN, MA, CCRN Department of Nursing APN, Critical Care In collaboration with: Joseph J. Chen, MD Lori Gingerich Roetlin, LISW, MSSA Clinical associate professor Neuroscience social work specialist Staff physiatrist and medical director Megan Farnsworth, RN, MNHP of Rehabilitation Services Department of Nursing Department of Orthopedics and Rehabilitation Intensive and Specialty Services Nursing Joseph D. Smucker, MD Division Assistant professor, Spine Surgery Judy A. Swafford, RN, BA, ONC Department of Orthopedics and Rehabilitation Department of Nursing Melanie J. House, MPT, NCS Orthopedics and Rehabilitation Senior physical therapist, Rehabilitation Therapies Neil A. Segal, MD Kimberly K. Hopwood, OTR/L Assistant professor and staff physiatrist Senior occupational therapist, Rehabilitation Therapies Department of Orthopedics and Rehabilitation Angela L. Carey, BSW Illustrations and design by: Social worker II, Social Services Loretta Popp, design artist, Graphics Department Center for Disabilities and Development The information in this publication is provided to educate and inform readers.
    [Show full text]
  • Thoracic Outlet Syndrome Medical Treatment Guidelines
    RULE 17, EXHIBIT 3 Thoracic Outlet Syndrome Medical Treatment Guidelines Adopted: December 8, 2014 Effective: February 1, 2015 Adopted: January 9, 1995 Effective: March 2, 1995 Revised: January 8, 1998 Effective: March 15, 1998 Revised: September 29, 2005 Effective: January 1, 2006 Revised: September 12, 2008 Effective: November 1, 2008 Presented by: DIVISION OF WORKERS' COMPENSATION TABLE OF CONTENTS SECTION DESCRIPTION PAGE A. INTRODUCTION .............................................................................................................................. 1 B. GENERAL GUIDELINES PRINCIPLES .......................................................................................... 2 1. APPLICATION OF GUIDELINES ....................................................................................... 2 2. EDUCATION ....................................................................................................................... 2 3. INFORMED DECISION MAKING ....................................................................................... 2 4. TREATMENT PARAMETER DURATION ........................................................................... 2 5. ACTIVE INTERVENTIONS ................................................................................................. 2 6. ACTIVE THERAPEUTIC EXERCISE PROGRAM .............................................................. 3 7. POSITIVE PATIENT RESPONSE ...................................................................................... 3 8. RE-EVALUATE TREATMENT EVERY
    [Show full text]
  • Developing a Standard of Care for Halo Vest and Pin
    Volume 42 & Number 3 & June 2010 169 Developing a Standard of Care for Halo Vest and Pin Site Care Including Patient and Family Education: A Collaborative Approach Among Three Greater Toronto Area Teaching Hospitals Angela Sarro, Tracy Anthony, Rosalie Magtoto, Julie Mauceri ABSTRACT Caring for an individual with a halo vest can be a frustrating and anxiety-provoking experience for healthcare professionals, the patient, and their families. Physicians or trained nurses apply halo vests in various situations in which cervical spine stabilization is required for an extended period. This device can be used as a first-line treatment in the management of nonoperative cervical trauma, that is, fractures, or placed following cervical surgery. Standardizing the application techniques and care associated with the halo vest, pin site care, and day-to-day activities of daily living will increase the comfort and self-confidence of healthcare professionals and the patient and family members in the provision of care. A collaborative approach among three greater Toronto area teaching hospitals aided in the development of standardizing care and patient educational materials for patients with halo vests. he halo brace is a device that is used to im- Literature Review mobilize the head and neck following a cervical A review of the nursing literature surrounding the Tfracture or postoperatively to allow bone heal- application, care, and management of halo vests and ing. The system consists of a ring that is attached to the pin sites is limited and outdated (Botte et al., 1996; outer table of the skull with four pins and supporting Marr & Edmonds, 1992; Marr & Reid, 1993; North, rods attached to a vest (Botte, Byrne, Abrams, & North, & Lee, 1992; Olson & Ustanko, 1990; Olson, Garfin, 1996).
    [Show full text]
  • Carpal Tunnel Syndrome, Humeral Epicondylitis, and the Cervical Spine
    BRITISH MEDICAL JOURNAL 12 JUNE 1976 1439 Discussion 1879.8 If there is clear evidence of clinical deterioration or there are focal neurological signs or there is a fractured skull, then One of the main aims in the management of head injuries is traumatic Br Med J: first published as 10.1136/bmj.1.6023.1439 on 12 June 1976. Downloaded from to ensure that complications are intracranial haematoma must be excluded before the prevented or, if this is not clinical state is ascribed to alcohol. In a patient who has taken possible, recognised soon enough to institute effective treat- alcohol and is in coma without focal ment. Even with reasonably prompt operations only a propor- signs or fracture some help of may be obtained from estimating the blood alcohol concentra- tion intracranial haematomas may be successfully treated, but tion; if it is under 43-4 this study indicates that when the operation is substantially mmol/l (200 mg/100 ml) altered con- delayed after clinical sciousness is unlikely to be due to alcohol alone.9 Whether a signs have been detected the mortalitv is traumatic intracranial haematoma is present, however, can be increased. Indeed, in this series several intracranial haematrsmas resolved were first discovered at necropsy. only by further investigation. The In the patient suspected of having had a cerebrovascular commonest reason for failing to recognise an intracranial accident the detection of a fractured skull haematoma is mistakenly attributing the depressed conscious is the best clue to to a management. All but four of the 33 patients with traumatic level cerebrovascular accident or excess alcohol.
    [Show full text]
  • Internet Movie Talking Points
    Distribution Information AAE members may reprint within their practice to help answer questions from patients or referring dentists. Internet Movie Talking Points When is a root canal treatment recommended? Root canal treatment is necessary when the pulp, the soft tissue inside the root canal, becomes inflamed or infected, most commonly due to decay. Root canal treatments are the recommended course of action when a tooth becomes infected because the procedure alleviates patients’ pain and saves a patient’s natural teeth from extraction. There are many clinical reasons for recommending root canal treatment, and there are also many practical reasons why saving the natural tooth is a wise choice, as opposed to extraction. What happens during a root canal? When a severe infection in a tooth requires endodontic treatment, that treatment is designed to eliminate bacteria from the infected root canal, prevent reinfection of the tooth and save the natural tooth. When one undergoes a root canal, the inflamed or infected pulp is removed and the inside of the tooth is carefully cleaned and disinfected, then filled and sealed. The following is a more detailed, step-by-step explanation of the root canal procedure: 1. The endodontist examines and takes x-rays of the tooth, then administers local anesthetic. After the tooth is numb, the endodontist places a small protective sheet called a “dental dam” over the area to isolate the tooth and keep it clean and free of saliva during the procedure. 2. The endodontist makes an opening in the crown of the tooth. Very small, specialized instruments are used to clean the pulp from the pulp chamber and root canals and to shape the space for filling.
    [Show full text]
  • The History of Craniotomy for Headache Treatment
    Neurosurg Focus 36 (4):E9, 2014 ©AANS, 2014 The history of craniotomy for headache treatment RACHID ASSINA, M.D., CHRISTINA E. SArrIS, B.S., AND ANTONIOS MAmmIS, M.D. Department of Neurological Surgery, New Jersey Medical School, Rutgers University, Newark, New Jersey Both the history of headache and the practice of craniotomy can be traced to antiquity. From ancient times through the present day, numerous civilizations and scholars have performed craniotomy in attempts to treat head- ache. Today, surgical intervention for headache management is becoming increasingly more common due to im- proved technology and greater understanding of headache. By tracing the evolution of the understanding of headache alongside the practice of craniotomy, investigators can better evaluate the mechanisms of headache and the therapeu- tic treatments used today. (http://thejns.org/doi/abs/10.3171/2014.1.FOCUS13549) KEY WORDS • headache • migraine • craniotomy • trepanation EADACHE has been described as long as human From Prehistory Through the Babylonian Period history has been recorded, having made its way into myth, magic, theology, and medicine. It has The prehistoric era was marked by the lack of un- Htouched ordinary, privileged, and famous people, baf- derstanding of the human body and of the concept of fling the minds of the earliest physicians, who eagerly disease and its origin. This period is also known in the sought for means to explain its occurrence and methods neurosurgical field as the age of trepanation; that is, the for its treatment. Its history can be traced back at least removal of a piece of bone from the skull. Whereas the 4000 years to Mesopotamian ritual texts.14 Headache was earliest documented descriptions of headache only date initially viewed as a spiritual entity rather than a symp- back 4000 years, its treatment may be traced back to the tom of various physical diseases.
    [Show full text]
  • Anatomical Network Analyses Reveal Oppositional Heterochronies in Avian Skull Evolution ✉ Olivia Plateau1 & Christian Foth 1 1234567890():,;
    ARTICLE https://doi.org/10.1038/s42003-020-0914-4 OPEN Birds have peramorphic skulls, too: anatomical network analyses reveal oppositional heterochronies in avian skull evolution ✉ Olivia Plateau1 & Christian Foth 1 1234567890():,; In contrast to the vast majority of reptiles, the skulls of adult crown birds are characterized by a high degree of integration due to bone fusion, e.g., an ontogenetic event generating a net reduction in the number of bones. To understand this process in an evolutionary context, we investigate postnatal ontogenetic changes in the skulls of crown bird and non-avian ther- opods using anatomical network analysis (AnNA). Due to the greater number of bones and bone contacts, early juvenile crown birds have less integrated skulls, resembling their non- avian theropod ancestors, including Archaeopteryx lithographica and Ichthyornis dispars. Phy- logenetic comparisons indicate that skull bone fusion and the resulting modular integration represent a peramorphosis (developmental exaggeration of the ancestral adult trait) that evolved late during avialan evolution, at the origin of crown-birds. Succeeding the general paedomorphic shape trend, the occurrence of an additional peramorphosis reflects the mosaic complexity of the avian skull evolution. ✉ 1 Department of Geosciences, University of Fribourg, Chemin du Musée 6, CH-1700 Fribourg, Switzerland. email: [email protected] COMMUNICATIONS BIOLOGY | (2020) 3:195 | https://doi.org/10.1038/s42003-020-0914-4 | www.nature.com/commsbio 1 ARTICLE COMMUNICATIONS BIOLOGY | https://doi.org/10.1038/s42003-020-0914-4 fi fi irds represent highly modi ed reptiles and are the only length (L), quality of identi ed modular partition (Qmax), par- surviving branch of theropod dinosaurs.
    [Show full text]
  • Diverging Development of Akinetic Skulls in Cryptodire and Pleurodire Turtles: an Ontogenetic and Phylogenetic Study
    69 (2): 113 –143 © Senckenberg Gesellschaft für Naturforschung, 2019. 2019 VIRTUAL ISSUE on Recent Advances in Chondrocranium Research | Guest Editor: Ingmar Werneburg Diverging development of akinetic skulls in cryptodire and pleurodire turtles: an ontogenetic and phylogenetic study Ingmar Werneburg 1, 2, *, Wolfgang Maier 3 1 Senckenberg Center for Human Evolution and Palaeoenvironment (HEP) an der Eberhard Karls Universität Tübingen, Sigwartstr. 10, 72076 Tü- bingen, Germany — 2 Universität Tübingen, Fachbereich Geowissenschaften, Hölderlinstraße 12, 72074 Tübingen, Germany — 3 Universität Tübingen, Fachbereich Biologie, Auf der Morgenstelle 28, 72076 Tübingen, Germany — * [email protected] Submitted September 5, 2018. Accepted January 15, 2019. Published online at www.senckenberg.de/vertebrate-zoology on February 19, 2019. Published in print on Q2/2019. Editor in charge: Uwe Fritz Abstract Extant turtles (Testudines) are characterized among others by an akinetic skull, whereas early turtles (Testudinata) still had kinetic skulls. By considering both ontogenetic and evolutionary adaptations, we analyze four character complexes related to the akinetic skull of turtles: (1) snout stiffening, (2) reduction of the basipterygoid process, (3) formation of a secondary lateral braincase wall, and (4) the fusion of the palatoquadrate cartilage to the braincase. Through ontogeny, both major clades of modern turtles, Pleurodira and Cryptodira, show strikingly different modes how the akinetic constructions in the orbitotemporal and quadrate regions are developed. Whereas mainly the ascending process of the palatoquadrate (later ossifed as epipterygoid) contributes to the formation of the secondary braincase wall in Cryptodira, only the descending process of the parietal forms that wall in Pleurodira. This is related to the fact that the latter taxon does not develop an extended ascending process that could ossify as the epipterygoid.
    [Show full text]