No neurological involvement for more than 40 years in Klippel-Feil syndrome with severe hypermobility of the upper cervical spine

We report the case of a 42-year-old woman with Klippel-Feil syndrome, who s howed severe hypermobility of the upper cervical spine without neurological involvement for more than 40 years. Radiographs revealed the presence of t he odontoid bone and fusion of the atlas, odontoid bone, and occiput. Conge nital fusion was present from the axis to C5 as a block vertebra. Lateral f lexion-extension radiographs revealed severe hypermobility at the junction between the odontoid bone and the axis. Prophylactic surgical stabilization has been recommended in patients with severe hypermobility, but adjacent d isc problems may possibly occur at the unfused levels in the future. We bel ieve that early prophylactic stabilization should not be indicated for Klip pel-Feil syndrome without neurological involvement only because of hypermob ility.