Wildervanck syndrome is typically characterized by three primary findings (triad). These include abnormal union or fusion of two or more bones of the spinal column (vertebrae) within the neck (Klippel-Feil syndrome); impairment or absence of certain eye (ocular) movements (Duane syndrome); and hearing impairment that is present at birth. However, according to some reports, this triad may be incomplete in some individuals with Wildervanck syndrome. In addition, in some cases, additional physical findings or intellectual disability may be present.
Researchers have described three major subtypes of Klippel-Feil syndrome (KFS). According to this classification, KFS type I is characterized by extensive fusion of vertebrae of the neck (cervical vertebrae) and the upper back (i.e., upper thoracic vertebrae). In KFS type II, there is localized union or fusion at one or two cervical or thoracic vertebrae associated with incomplete development of one half of certain vertebrae (hemivertebrae) or other malformations of cervical vertebrae. KFS type III is characterized by fusion of vertebrae of the neck as well as vertebrae of the upper or lower back (i.e., lower thoracic or lumbar vertebrae).
Individuals with Wildervanck syndrome who are affected by KFS also tend to have an unusually short neck. In severe cases, the head may appear to be situated directly on the trunk. KFS may also be associated with limited movements of the head and neck and a low hairline at the back of the head (posterior hairline) that may extend to the shoulders. In addition, the face often appears dissimilar from one side to the other (facial asymmetry), and the neck may be abnormally twisted (torticollis), with the head rotated into an abnormal position. Some individuals with KFS may have a risk of developing neurological complications due to instability of cervical vertebrae and associated spinal cord injury that may occur spontaneously or following minor trauma. Such complications may include associated pain; unusual sensations (paresthesia), such as tingling or prickling; increased reflex reactions (hyperreflexia), Weakness or Paralysis of one side of the body (hemiplegia) or of the legs and the lower part of the body (paraplegia), or other findings. According to some researchers, evidence suggests that Wildervanck syndrome may be a clinical variant of KFS. (For further information on KFS, please see the “Related Disorders” section of this report below.)
In some instances, Wildervanck syndrome may also be characterized by additional skeletal abnormalities. These may include incomplete development of certain vertebrae, leaving a portion of the spinal cord exposed (spina bifida); abnormal curvature of the spine (scoliosis), rib defects; and/or a condition known as Sprengel’s deformity. This condition is characterized by elevation and/or underdevelopment of the shoulder blade (scapula), limited movement of the arm on the affected side, and the development of a lump at the base of the neck due to elevation of the shoulder blade. There are some patients that only have an abnormal curvature of the spine (scoliosis).
As mentioned above, Wildervanck syndrome is also associated with Duane syndrome, a condition characterized by limitation or absence of certain horizontal eye movements and other eye (ocular) abnormalities. In those with Duane syndrome, there may be an impaired or absent ability to move the eyes outward (abduction), inward (adduction), or both. In addition, upon attempting to look inward, there may be abnormal narrowing of the eye slit (palpebral fissure narrowing) and retraction or “drawing back” of the eyeball into the eye cavity (orbit). Such abnormalities may affect one or both eyes (unilateral or bilateral). In some cases, affected individuals may also have abnormal inward or outward deviation of one eye in relation to the other (convergent or divergent strabismus).
In some individuals with Wildervanck syndrome, additional ocular abnormalities may be present. For example, some affected individuals may have pseudopapilledema, a condition in which Swelling of the optic disc may be present from birth for unknown reasons. The optic disc, also known as the “blind spot,” is the portion of the optic nerve that joins with the nerve-rich innermost region of the eye (retina). Additional ocular abnormalities may include incomplete or partial dislocation of the lenses of both eyes (bilateral subluxation), the formation of cysts on the eyeballs (epibulbar dermoids and lipodermoids) and drooping of the upper eyelids causing a narrowing of the palpebral aperture (blepharoptosis).
Wildervanck syndrome is also typically associated with hearing impairment at birth (congenital). Such Hearing loss may result from impaired transmission of sound from the outer or middle ear to the inner ear (conductive hearing loss); failed transmission of sound impulses from the inner ear to the brain (sensorineural hearing loss); or both (mixed hearing loss). One or both ears may be affected (unilateral or bilateral hearing impairment). According to some reports, most affected individuals have sensorineural Hearing loss due to structural abnormalities of the inner ear. For example, there may be abnormalities of the coiled bony passage (cochlea) that transforms sound vibrations into nerve impulses for transmission to the brain. Additional defects may include underdevelopment or malformation of regions involved with the sensation of position, movement, and balance (vestibular apparatus); absence of the nerve that conveys impulses for the sensation of sound and balance to the brain (vestibulocochlear nerve); and/or other abnormalities.
Some individuals with Wildervanck syndrome may also have additional abnormalities. For example, some may have malformations of the head and facial (craniofacial) area, such as an abnormally small head (microcephaly) or incomplete closure of the roof of the mouth (cleft palate). In addition, in some cases, Wildervanck syndrome may be associated with hydrocephalus, a condition in which there is obstructed flow or impaired absorption of the fluid surrounding the brain and spinal cord (cerebrospinal fluid [CSF]), resulting in increasing fluid pressure in the brain. Rarely, in some affected infants, there may be protrusion of the membranes surrounding the brain (meninges) through a defect in the back of the skull (occipital meningocele). Additional physical features may include abnormal outgrowths of skin (skin tags) or pits in front of the ears (preauricular tags and pits); kidney (renal) defects; the presence of lumps of solid matter (gallstones) within the gallbladder (cholelithiasis).
Some patients with structural malformations of the heart have been reported, (congenital heart [cardiac] defects). Cardiac defects may include an abnormal opening in the fibrous partition (septum) that separates the upper or lower chambers of the heart (atrial or ventricular septal defects) and little holes in the heart valves (aortic valve fenestration). Recently, some patients were reported with dilatation of the arteries from the heart (aneurism of the coronary artery) or rupture of the arteries of the spine (vertebral artery dissection). There are also some patients with associated vascular malformations such as only one artery of the heart (single coronary artery) or the persistence of a vena in the thorax that should disappear before birth (persistent left superior vena cava).
In addition, although intelligence is usually normal, intellectual disability has been reported in some affected individuals. Short stature has also been seen in some patients, and one individual was diagnosed with idiopathic growth hormone deficiency.