Type I Chiari malformation consists on the caudal displacement of cerebellar tonsils through the foramen magnum. It is often asymptomatic, although it may display symptoms as a result of cerebellum, brainstem, high cervical spinal cord or the lower cranial nerve, involvement.
We report our experience over the last 16 years. We have identified 16 patients with type I Chiari malformation. Only 2 cases showed common type I Chiari symptoms and just one had respiratory disorder as the first clinical sign.
A 15 year old girl presented with a 5 years' history of chronic daily cough aggravated by exercise. Snoring and sleep apnea had been noted by her mother for 1 year. The girl eventually suffered from migraine and diurnal hypersomnolence. The physical and neurological examination was normal with the only exception being the absence of bilateral nauseous reflex. A nocturnal polysomnography study demonstrated a pseudoperiodic pattern with apnea pauses associated to cycles of deep breathing, resulting in severe gasometric repercussion and bradycardia. Magnetic resonance imaging of the brain showed Chiari I malformation. Non-invasive mechanical ventilation treatment significantly improved the clinical symptoms and gasometric analysis.
Surgical posterior fossa decompression is discussed. Early decompression before appearance of irreversible neurological damage is recommended. It is associated with a significant reduction in the number of central apneas and sleep arousals. Surgical intervention is recommended in symptomatic patients and in cases of radiographic Chiari malformation or syrinx progression.