Rapidly progressing monoparesis caused by Chiari malformation type I without syringomyelia
An 11-year-old girl presented with the gradual onset over one day of sensory dysesthesia of her left forearm followed the day of admission by severe monoparesis of the ipsilateral forearm, increasing dysesthesia, and dysphagia. She recalled that the day the symptoms developed, she swam faster and for a longer duration than usual. She was referred to our hospital one week from the onset because her symptoms had not resolved. Her past history was significant for hydrocephalus from aqueductal stenosis that was diagnosed and treated when she was aged 1 year. Her ventriculomegaly and symptoms at that time resolved completely following endoscopic third ventriculoscopy. CM-I was diagnosed by radiographic criteria. During the subsequent 10 years, she received annual MRI and neurological examinations that documented persistent tonsillar ectopia but no neurological deficits.\nOn admission, her physical examination revealed spastic paresis of left upper limb, with the limb assuming a peculiar posture at rest, with the wrist in extension and the elbow joint in flexion []. The other elements of neurological examination, mental status, cranial nerves, motor, sensory, cerebellar, and deep tendon reflexes were normal except for decreased gag reflex. Besides, she had neither headache, neck pain nor motor deficits of lower extremities, and denied experiencing any Valsalva-induced symptoms. There was no known history of head trauma.\nMRI a week from the onset showed cerebellar tonsillar herniation of 8 mm below McRae's (basion-opisthion) line, which was the same amount as on previous imaging. No recurrence of hydrocephalus was demonstrated [Figure –]. There was no evidence of syringomyelia or abnormal T2 signal in the spinal cord [Figure and ]. Sagittal fast imaging employing steady state acquisition (FIESTA) MRI clearly showed that compared with the previous in detail, the tonsil changed into beaked shape and was asymmetry []. Clinical signs and symptoms pointed to dysfunction of the cervicomedullary junction despite stable imaging findings. Surgical treatment consisting of FMD, C1 laminectomy and duraplasty was performed without complication.\nAfter the operation, dysesthesia and monoparesis of left forearm and dysphagia improved steadily. She was discharged on the 14th postoperative day with complete neurological recovery. At the follow-up 6 months after FMD, she maintained her recovery. Postoperative MRI demonstrated an ascent of the cerebellar tonsil of 4 mm compared with before FMD [].