Chiari I Malformation With Syrinx Martha D. Carlson, MD, PhD*, and Karin M. Muraszko, MD † The Chiari I congenital malformation is characterized by caudal displacement of the cerebellar tonsils through the cervical canal. Although this malformation is often asymptomatic, coexisting syringomyelia can result in neurologic symptoms. We report a case of progressive ataxia with brainstem dysfunction in an adolescent female manifesting a severe Chiari I mal- formation with syrinx. Chiari decompression 4 years after initial presentation led to rapid improvement in most of her long-term symptoms. This case demon- strates the importance of consideration of Chiari I with syringomyelia in the differential diagnosis of progres- sive ataxia and brainstem symptoms. © 2003 by Elsevier Inc. All rights reserved. Carlson MD, Muraszko KM. Chiari I malformation with syrinx. Pediatr Neurol 2003;29:167-169. Introduction Chronic progressive ataxia can have multiple etiologies. In the adolescent age group, Friedreich’s ataxia or other genetic spinocerebellar ataxias are often a consideration. Congenital malformations such as Chiari I with syringo- myelia, one etiology to consider in the differential diag- nosis, can be overlooked if dedicated neuroimaging (cer- vical spine MRI) is not done. Chiari I malformation involves caudal displacement of the cerebellar tonsils into the spinal canal. A case of progressive ataxia with brain- stem dysfunction is described, in which neurosurgical decompression of the Chiari I and syrinx many years after the onset of symptoms resulted in a remarkable recovery. Case Report A 14-year-old female presented for a second opinion with a 4-year history of progressive ataxia. At referral, the presumptive diagnosis was atypical Friedreich’s ataxia. She described the fairly acute onset of dizziness and neck pain after a fall from the monkey bars on the school playground. The neck pain developed into posterior headaches with nausea and intermittent vomiting. Results of a computed tomography test of her head were unremarkable. Several months later, she began to notice changes in her gait and manifested poor balance. Throughout the next year, her family noticed a change in her speech and had difficulty understanding her. She developed swallowing difficulty and manifested an absent gag. She also described changes in her vision, stating that focusing was difficult because her eyes jerked (nystagmus). She had no history of seizure or cognitive decline (she was on the honor roll in the eighth grade). On examination, she was alert, with normal cognition and language. Her speech exhibited ataxic and spastic dysarthria. On cranial nerve testing, she manifested mild overshoot dysmetric saccades and down- beating nystagmus in all positions of gaze (but more notable to the left). She had full visual fields to confrontation testing and conjugate extraoc- ular movements. Funduscopic examination revealed sharp disc margins. Hearing was intact to finger rub. She manifested mild tongue atrophy and no gag. On sensory examination, she reported decreased sensation to pinprick and temperature on the left side of her face. On motor examination, there was mild diffuse muscle weakness at 4+/5. There was no obvious proximal or distal right or left gradient. She exhibited mild muscle atrophy but no fasciculation. On sensory testing, there was decreased pinprick and temperature sensation in the right hemibody. Vibration and proprioception testing were normal. Deep tendon reflexes were graded at 3+/5. Plantar responses were extensor bilaterally. On finger-to-nose testing, there was dysmetria bilaterally. She manifested a wide-based markedly ataxic gait but was able to walk on her heels and toes with assistance. Her feet exhibited mild hammertoe and pes cavus deformity. She could not tandem walk. Romberg’s test was negative. General examination revealed only mild scoliosis. In summary, a 14-year-old female presented withchronic progressive ataxia and lower brainstem dysfunction. On examination, she manifested ataxic and spastic dysarthria, gait ataxia, nystagmus, absent gag, crossed sensory findings, and mild diffuse weakness with hyperreflexia and upgoing toes, all suggestive of cerebellar and brainstem involvement (posterior fossa) with corticospinal tract dysfunction. The down-beating nystagmus localizes to the cervicomedullary junction. The diminished pinprick and temperature sensation in the left side of the face and right hemibody are consistent with brainstem localization. Dorsal column function was normal, with intact vibration and proprioception. She exhibited brisk reflexes with extensor plantar responses. Initial neurologic evaluation about 1 year into her treatment course was suggestive of a variant form of Friedreich’s ataxia with retained deep tendon reflexes, which was likely based in part on the negative results of her computed tomographic imaging. When the trinucleotide repeat genetic testing for Friedreich’s ataxia became available, her results were negative. The differential diagnosis of progressive ataxia includes other rare biochemical and genetic entities such as vitamin E deficiency, Abetali- poproteinemia, acanthocytosis, pyruvate dehydrogenase deficiency, Hartnup’s disease, Refsum’s disease, juvenile -galactosidase and aryl- sulfatase deficiencies, and biotinidase deficiency. From the *Division of Pediatric Neurology, Departments of Pediatrics and Neurology, and the † Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan. Communications should be addressed to: Dr. Carlson; Pediatric Neurology Metabolic Clinic; Box 0202/L3222; Women’s Hospital; University of Michigan Health System; 1500 East Medical Center Drive; Ann Arbor, MI 48109-0202. Received December 10, 2002; accepted March 3, 2003. 167 © 2003 by Elsevier Inc. All rights reserved. Carlson and Muraszko: Chiari I Malformation With Syrinx doi:10.1016/S0887-8994(03)00217-0 ● 0887-8994/03/$—see front matter