Spina Bifida Occulta

This common anomaly consists of a midline defect of the vertebral bodies without protrusion of the spinal cord or meninges. Most individuals are asymptomatic and lack neurologic signs, and the condition is usually of no consequence. In some cases, patches of hair, a lipoma, discoloration of the skin, or a dermal sinus in the midline of the lower back suggests a more significant malformation of the spinal cord .

A spine roentgenogram in simple spina bifida occulta shows a defect in closure of the posterior vertebral arches and laminae, typically involving L5 and S1; there is no abnormality of the meninges, spinal cord, or nerve roots. Spina bifida occulta is occasionally associated with more significant developmental abnormalities of the spinal cord, including syringomyelia, diastematomyelia, and a tethered cord. These are best identified with MRI . Some consider the term spina bifida occulta to denote merely a posterior vertebral body fusion defect. This simple defect does not have an associated spinal cord malformation.
 Other clinically more significant forms are more correctly termed occult spinal dysraphism.
In most of these cases, there are cutaneous manifestations such as a hemangioma, pit, lump, or hairy patch .
A dermoid sinus usually forms a small skin opening, which leads into a narrow duct, sometimes indicated by protruding hairs, a hairy patch, or a vascular nevus. Dermoid sinuses occur in the midline at the site of where meningoceles or encephaloceles may occur: the lumbosacral region or occiput. Dermoid sinus tracts may pass through the dura, acting as a conduit for the spread of infection. Recurrent meningitis of occult origin should prompt careful examination for a small sinus tract in the posterior midline region, including the back of the head. Lower back sinuses are usually above the gluteal fold and are directed cephalad. Tethered spinal cord syndrome may also be an associated problem.