Final answer:
Spina bifida occulta is the form of spina bifida associated with a tuft of hair or skin dimple at the level of the bone defect. It is the mildest form and usually asymptomatic.
Step-by-step explanation:
The form of spina bifida that is associated with a tuft of hair or skin dimple at the level of the bone defect is called spina bifida occulta.
Spina bifida occulta is the mildest form of spina bifida, where the vertebral bones do not fully surround the spinal cord, but the spinal cord itself is not affected. It is usually asymptomatic and may only be discovered incidentally when imaging studies are performed.
Other forms of spina bifida, such as meningocele and myelomeningocele, involve the protrusion of the meninges and spinal nerves with more severe neurological symptoms.