Rudimentary third lower limb in association with spinal dysraphism: Two cases

Spinal dysraphism is a common congenital anomaly with many associated variants. One of the rarest associated findings is a full grown or rudimentary third limb, collectively called Tripagus. We present two cases of spinal dysraphism with rudimentary third limb arising from the ilium.

efects in the early embryonic stages produce spinal urogenital abnormalities were detected. dysraphism, which is characterized by anomalous differentiation and fusion of dorsal midline Magnetic resonance imaging (MRI) confirmed these structures. Spinal dysraphism may be categorized clinically findings of lipomeningocele with dermal sinus and bony into two subsets, open spinal dysraphism and closed spinal strut. These bony structures may represent a dysraphism. Rudimentary accessory (third) limb is a very developmentally abortive accessory limb [ Figure 1]. rare anomaly seen in association with spinal dysraphism. We present two such cases.

Case 2
A nine-year-old boy presented with complaints of CASE REPORTS progressive difficulty in walking, urinary incontinence and deformity and nonhealing ulcers of the feet since past one year and a history of a swelling over the sacral region A 11-year-old boy presented with progressive weakness in present since birth, which was constant in size. the right lower limb and a soft swelling over the lower back since birth. Patient had history of urinary incontinence.
On examination, he had weakness in both his lower limbs, Examination revealed a soft, nontender, compressible muscle wasting of both legs (more on the left side) and his immobile swelling and presence of two nondischarging left foot had an equinus deformity. Plain radiograph of the lumbosacral spine [ Figure 2] showed absence of the left side of the sacrum (Scimitar sacrum) and spina bifida of the L5 vertebra. Soft tissue swelling over the sacrum was also visible. a mesodermal blastema that is a result of de-differentiation from Schwann cells. 2 A primary mesodermal defect involving both the limb bud and the adjacent para-axial mesoderm may explain the association of this anomaly with spina bifida. 7 A possibility of twinning has also been postulated in an accessory limb arm. 8 Developmentally aborted accessory limb may be an incidental finding in a patient presenting with neurological or other complaints associated with spinal dysraphism.
In cases like ours, diagnosis of an abortive limb is mainly radiological as there may be no clinical sign to suggest its presence. It may be seen on plain radiograph as a bony strut arising from pelvic bones. It is well appreciated on CT or MRI. These bones have well formed cortex and medulla and follow the intensity of normal bones on MRI. Rudimentary joint may be present as well. There may be muscles attached to these bones.
MRI is the modality of choice, as it can assess other associated conditions like myelomeningocele, lipomeningocele, split cord malformations, dermal sinuses and associated anomalies. Treatment in the form of surgical correction has been mentioned in cases with completely developed third limb. It includes excision of the accessory limb or at times disarticulation and reconstruction of the accessory limb which has no innervation with removal of one set of duplicated lower genitourinary and alimentary tracts with reconstruction of the pelvis. 9 In a case of dipegus, mentioned in the literature, with three accessory legs, the parasitic pelvis and rest of the legs were extirpated with an attempt to correct the associated anorectal or genitourinary malformation. 6 The exact role of surgery in rudimentary or aborted accessory limb as in our case, where there was no cosmetic  A full grown or rudimentary third limb is a very rare association seen with spinal dysraphism and few cases are mentioned in the literature 1-5 but its exact incidence is unknown. Various associations of urogenital duplication, anorectal malformation and other anomalies have been found. 6 Accessory limb may be a result of very early splitting of the limb bud arising from the paraxial mesoderm. It is proposed that the growth of the accessory limb occurs from defect or neurological manifestation due to it, remains questionable.