Morbus de Anquin or spinous engagement syndrome. A rare cause of low-back pain syndrome and sciatica.

We report on a rare disease called to Anquin's disease or spinous engagement or impingement syndrome. Low-back pain in this specific syndrome probably combined with sciatica is caused by a hypertrophic spinous process along with a spina bifida occulta of the underlying vertebra. Mostly, the enlarged spinous process is seen at L5 and the spina bifida occulta at S1. Conservative therapy consists of physiotherapy with postural exercises including improvement of lumbar flexion. If conservative treatment is unsuccessful, surgical treatment is indicated. Surgical therapy should include resection of the hypertrophic spinous process, probably combined with revision of the nerve roots and division of adhesions. Between 1981 and 1993 six patients were treated surgically after long-lasting periods of conservative therapy. All patients were re-examined clinically and radiologically after a mean follow-up period of 2.9 years. In all but one patient a distinct release from lumbar back pain and/or sciatica was observed. Regarding this, the most important fact in de Anquin's disease is to be aware of this specific syndrome. If low-back pain can be traced to a hypertrophic spinous process the first choice of therapy should be conservative. In unsuccessful cases simple surgical resection probably combined with division of the adhesion can lead to significant release from pain and is recommended.