Atypical Presentation of Chiari I Malformation in a 13-Year-Old Adolescent Rachel S. Bronheim, BA* and Rachana Tyagi, MD† Abstract: In this report, we describe a 13-year-old with opisthotonos as the presenting symptom of Chiari I malformation. This presentation is rare and has previously been reported only in infants. We describe the physical and radiologic findings, literature regarding Chiari malformation, and dif- ferential diagnosis of opisthotonos in this patient. Key Words: Chiari malformation, neck pain, opisthotonos (Pediatr Emer Care 2019;35: e72–e75) C hiari type I malformation has a typical and well-known con- stellation of clinical symptoms. These most commonly include headache, cerebellar dysfunction, scoliosis, spasticity, and bulbar palsies. Typical presentation patterns include occipital or cervical headaches, sometimes accompanied by persistent neck and shoul- der pain and sometimes associated with Valsalva maneuvers. 1–3 Neurologic findings, such as weakness; hyperreflexia; long tract dysfunction affecting gait, bowel, and bladder function; and a Babinski response, are also common presentations of Chiari I malformation. 3 Opisthotonos is a rare manifestation of Chiari I malformation, usually in infants. More typically, opisthotonos oc- curs as a symptom of meningitis or tetanus. 4 We report a rare clin- ical presentation of Chiari I malformation in a 13-year-old male adolescent whose primary presenting symptom was opisthotonos and discuss the implications for diagnosis of Chiari I in the adoles- cent age group. CASE Clinical Presentation A 13-year-old male adolescent with a medical history of mild persistent asthma was admitted for development of muscle spasms in his left hand and neck. This mild episode was followed by 2 more severe spasms of the neck, back, and upper extremities, consistent with opisthotonos. Prior to these episodes, the patient had not exhibited these symptoms. Toxicology screens for salicylates, alcohol, acetaminophen, opiates, phencyclidine, cocaine, barbitu- rates, benzodiazepines, and tetrahydrocannabinol were performed and found to be negative. The neurological examination was signifi- cant for slight left hand weakness and difficulty with tandem gait. He had no cutaneous stigmata of tethered cord. Seizures were presumed to be unlikely, as the patient was fully awake during each episode. A computed tomography scan was obtained and revealed dila- tation of the lateral and third ventricles. Magnetic resonance imag- ing (MRI) of the brain was performed, demonstrating a Chiari I malformation with the tonsils herniating 13.2 mm below the fora- men magnum, a C6–C7 syrinx with a craniocaudal length of 19.9 mm, and a maximal transverse diameter of 5.1 mm (Fig. 1). Thoracic MRI ruled out the extension of the syrinx into the tho- racic cord, and a lumbar MRI ruled out a tethered cord (Figs. 2 and 3). The patient underwent flexion/extension imaging to rule out occipito-cervical instability (which would require fusion as well as decompression) associated with the abnormal retroverted dens, which contributed to the deformity and further compressed the brainstem/cord (Fig. 4). Intervention and Outcome A suboccipital craniectomy and C1 laminectomy were per- formed, and an intraoperative ultrasound was performed to assess ad- equacy of decompression. As persistent compression and pistoning of the tonsils was noted, a duraplasty without coagulation of the ton- sils was also performed. Repeat ultrasound imaging showed adequate cerebrospinal fluid present posterior to the tonsils after duraplasty. The postoperative course was uncomplicated. The patient initially complained of incisional headaches postoperatively, which eventu- ally resolved, and had otherwise normal neurological examinations without any new deficits. Follow-up imaging 2 months postopera- tively demonstrated an improvement in tonsil herniation magnitude (Fig. 5), and postoperative MRI approximately 11 months postoper- atively showed resolution of the syrinx (Fig. 6). The hand weakness also resolved. At this point in time, the patient was released to play football. DISCUSSION Chiari Malformation Chiari malformation is a congenital abnormality in which the cerebellar tonsils and medulla oblongata herniate through the fo- ramen magnum into the spinal canal. 5 It is classified into 3 differ- ent types, according to degree of herniation. Type I is classified by the movement of the cerebellar tonsils, but generally not the me- dulla, below the foramen magnum. 1 Type II is characterized by the herniation of the cerebellar tonsils, fourth ventricle, vermis, and medulla through the foramen magnum into the spinal canal This occurs in combination with a myelomeningocele. 2 Type III is characterized by a complete herniation of the cerebellar tonsils and the medulla through a posterior skull defect, forming a high cer- vical or occipital encephalocele. 6 Chiari malformation may be ac- companied by hydrocephalus, spina bifida, syringohydromyelia, or cognitive defects related to primary malformations associated with myelomeningocele. 5,7 The pathophysiology of Chiari I malformation is not clear, al- though several researchers have postulated the etiology of the anom- aly. Some hypotheses focus on the underdevelopment of posterior fossa structures, whereas others point to anomalies that increase intra- cranial pressure as causal mechanisms of Chiari I malformation. 8 More recently, it has been theorized that the small posterior fossa may be considered part of a spectrum of craniovertebral junction anomalies that result in abnormal osteoneural relationships. 9 Before MRI became widely utilized, Chiari I malformation was thought to be an adult disorder. However, as MRI became From the *Department of Medical Education, Icahn School of Medicine at Mount Sinai, New York, NY; and †Department of Neurosurgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ. Disclosure: The authors declare no conflict of interest. Reprints: Rachana Tyagi, MD, Clinical Academic Building, 125 Paterson St, Suite 2100, New Brunswick, NJ 08901 (e‐mail: tyagira@rwjms.rutgers.edu). Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0749-5161 ILLUSTRATIVE CASE e72 www.pec-online.com Pediatric Emergency Care • Volume 35, Number 4, April 2019 Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.