Acute deterioration in occult Chiari malformation following missile spinal trauma. Case report.

Patients with Chiari malformation (CM) Type I typically experience chronic, slowly progressive symptoms. Rarely, however, do they suffer acute neurological deterioration following an iatrogenic decrease in caudal cerebrospinal fluid pressure due to, for example, a lumbar puncture. To our knowledge, acute neurological deterioration following missile spinal injury in CM has not been previously described. The authors report on a 16-year-old girl who was shot in the abdomen and lumbar spine. Although neurologically intact on initial workup, she developed precipitous quadriplegia and apnea in a delayed fashion. Tonsillar herniation with medullary compression and cerebellar infarction was diagnosed on magnetic resonance imaging. Suboccipital decompression resulted in significant neurological improvement. Well-formed tonsillar ectopia diagnosed at surgery suggested a preexisting CM. The authors conclude that missile spinal trauma can precipitate medullary compression and acute neurological decline, especially in patients with preexisting tonsillar ectopia. Immediate operative decompression to relieve impaction at the cervicomedullary junction can result in significant neurological recovery.