A previously unreported variation in the anatomy of the spinal dural sheath was observed during routine cadaveric dissection, consisting of a duplication of the dural layer, with layers adherent throughout their length. The double dural sheath completely enveloped the spinal cord and nerve roots, and extended from C2 to L5: both layers were of similar thickness to a single dural sheath. Duplication of the dura mater in the form of two complete dural sheaths has not been previously observed and/or reported in a cadaveric study. However, areas of localised duplication of the ventral aspect of the dural sheath have been observed during intra-operative dissection, particularly in association with idiopathic herniation of the spinal cord. Complete duplication of the spinal dura mater is of clinical interest in spinal surgery, particularly in relation to idiopathic spinal cord herniation.
