Congenital torticollis (abnormal head position, AHP) is typically caused by a tight sternocleidomastoid muscle. These cases are evident during the first weeks of life and persist during sleep.
By contrast, acquired torticollis in infancy is often an adaptive response to an ophthalmic problem. Ocular torticollis/AHP often presents at 3 to 4 months of age. Younger infants don’t have sufficient neck strength to compensate for ocular issues. Ocular AHP typically disappears during sleep because there are no vision problems to compensate for when the eyes are closed.
Differentiating congenital from ocular torticollis is important. The consequences of inappropriate management can be profound. Specifically, initiating physical therapy for ocular torticollis will override the adaptive mechanism—the torticollis will be “treated”—but amblyopia will result as the underlying pathology remains unaltered.
Ocular torticollis is fairly easy to identify. There are just three diagnoses in the differential: strabismus, nystagmus, and ptosis. When evaluating any infant or child with an AHP, position their head in the primary (straight) position and watch the eyes. Is there strabismus? Nystagmus? Ptosis? If there is a tilt toward one shoulder, tilt the head toward the opposite shoulder. If nystagmus, strabismus, or ptosis is present, the torticollis should be considered ocular until proven otherwise.
Why would torticollis be an adaptive mechanism? For patients with nystagmus, there is often a particular head position where the nystagmus is minimized, and visual acuity improves. With strabismus, an AHP can eliminate double vision and enhance depth perception. Finally, a chin-up head position for bilateral ptosis allows the child to use both eyes and achieve depth perception.
With this in mind, the appropriate treatment for ocular AHP is to address the underlying ophthalmic pathology. Overriding the adaptive mechanism of an ocular AHP through physical therapy will cause amblyopia; this vision loss can be profound and permanent.
A few categorical details are in order. A tilt describes a head tilted toward one shoulder; a turn describes a face turn toward the left or right. Thus, we have head tilts and face turns. Chin-up and chin-down positions are self-explanatory. Combinations occur.
Nystagmus
Retinal cells are organized in linear arrays. When light moves across these arrays, the retina is stimulated and the light is perceived by the brain. Depending on the animal, either movement of an object or movement of the eyes will stimulate the retina.
Some animals are incapable of initiating eye movements (saccades) and only see when an object moves past their eyes (or if they move their heads—think of a lion moving its head slowly side to side as it walks). In primates (yes, us!), the extraocular muscles are tonically active, causing very small movements of the eyes (micro-saccades) that effectively “paint” an image onto the retina. Saccades are characterized by amplitude and frequency (gain = amplitude × frequency). Our retina can sense motion within a certain range of gain.
When a normal person’s eye movements are measured with electrodes, microsaccades are detected even though the eyes appear perfectly still. These micro-saccades are essentially the same regardless of gaze direction.
People born with an abnormal saccadic gain mechanism have infantile nystagmus. Their saccades are not “micro,” but rather an exaggeration of normal. Visual acuity is reduced because the saccadic gain exceeds the retina’s ability to process the information.
Importantly, patients with nystagmus often have one gaze position where the gain is minimized (the null zone). By directing their eyes into this zone, nystagmus decreases, and visual acuity improves.
Infants quickly discover this null zone and assume an abnormal head position (AHP) to force their gaze into it.
People with congenital nystagmus also have a null zone at near. When the eyes converge on a near object, gain is diminishe,d and visual acuity improves. As a result, they often read smaller print than their distance acuity would predict and frequently read standard print without visual aids.
Eye muscle surgery can shift the null zone into the primary (straight-ahead) position, mitigating or eliminating the need for an AHP.
Another consideration is self-esteem. Adults with nystagmus frequently report lifelong feelings of inadequacy and shame related to looking different and difficulty maintaining normal social eye contact.
Most patients also report improvement in visual acuity following surgery.
Ptosis
In congenital ptosis, the muscle-tendon complex that elevates the eyelid (levator aponeurosis) is abnormal, with excess elastic tissue and insufficient muscle. This results in poor lid elevation, lid lag, and poor formation of the upper lid crease.
In cases of marked bilateral ptosis, patients lift their head to see; otherwise, the lids block both pupils. Congenital ptosis does not resolve spontaneously, and there is no advantage to surgical delay when it causes an AHP. Delayed treatment can result in musculoskeletal changes to the face and neck. Our preference is to operate at the earliest safe opportunity after diagnosis.
Unilateral ptosis can also cause an AHP. Infants may raise their chin to use both eyes and maintain depth perception. A chin-up AHP is a favorable sign, indicating preserved binocularity. More concerning is severe unilateral ptosis without an AHP, suggesting amblyopia. Marked unilateral ptosis in infancy should be corrected promptly.
If ptosis is not severe enough to cause amblyopia or an AHP, it is reasonable to delay surgery until 4–5 years of age. Surgery may still be performed earlier if the family is highly motivated.
There are two primary methods for ptosis repair: tightening the levator muscle or mechanically lifting the lid with a suspension (sling). Each approach has advantages and limitations, and all suspension materials may fail over time.
The most common issue after pediatric ptosis surgery is the need for reoperation. Corneal dryness due to initial overcorrection is a more serious concern, particularly with suspension procedures, and requires diligent lubrication during sleep.
While the primary goal of ptosis repair is functional—eliminating AHP, treating amblyopia, and restoring binocularity—we also strive for excellent cosmetic outcomes.
Strabismus
Strabismus occurs when the eyes point in different directions, disrupting fusion and causing diplopia. When deviation is equal in all gaze directions, it is comitant. When it varies with gaze, it is incomitant. Patients with incomitant strabismus often adopt an AHP to maintain single vision and depth perception.
The most common types of incomitant strabismus are superior oblique palsy, Duane syndrome, and A- or V-pattern strabismus.
Superior Oblique Laxity (“Palsy”)
Superior oblique “palsy” is mechanical rather than neurologic. A lax tendon allows inferior oblique overaction, rotating the eye up and out. To compensate, patients tilt their head toward the opposite shoulder.
Superior oblique palsy often presents in infancy with a head tilt and is sometimes mistaken for congenital torticollis.
Early surgical correction is recommended to prevent facial asymmetry and neck deformity. Most cases are effectively treated with a single surgery.
Duane Syndrome
Duane syndrome results from aberrant innervation between the abducens and oculomotor nerves. One-third of patients have associated cervical, thoracic, or hearing abnormalities; hearing evaluation is recommended.
To avoid diplopia, patients assume an AHP. Duane Type 1 is most common, characterized by limited abduction and esotropia in primary gaze. Lid fissure narrowing and widening with gaze distinguish it from sixth nerve palsy.
Types 2 and 3 involve adduction deficits or combined movement limitations. All types may be unilateral or bilateral.
Treatment is surgical. There is no benefit to prolonged delay when AHP is present. The goal is straight eyes with a straight head.
A- and V-Pattern Strabismus
Pattern strabismus occurs when deviation varies vertically. Patients adopt an AHP to achieve fusion.
Strabismus surgery is highly effective in treating pattern deviations.
