Chapter 81 Abnormal head postures
causes and management
General considerations
Abnormal head postures (AHPs) are frequent in pediatric ophthalmology. The medical term is torticollis from the Latin prefix “tortus” (twisted) and “collum” (neck).1,2 The term is applied to muscular or neurologic disorders that cause unnatural positions of the head.1,3 The eye-related conditions that lead to AHPs are termed ocular torticollis.4–6
Physiological basis of head postures
Normal head position is maintained by inputs from the otolith apparatus, the semicircular canals within the labyrinth, the proprioceptors in the neck and the retina. The labyrinth is the sense organ for static and dynamic head movement. The otolithic apparatus responds to static head position. It is activated during maneuvers such as head tilting to one shoulder. The semicircular canals respond to dynamic head movements in any of the three dimensions.1,3,7
Input from these sources travels to the vestibular brainstem nuclei and from there to the vestibular cortex and to the cervical cord and neck muscles. There are also direct pathways from the labyrinth to the extraocular muscles in response to changes in the semicircular canals. Cerebellar projections and cervical proprioceptive input are integrated into the system.2,4,7 Integration of input from the retinas leads to fine adjustments in head position.2
The muscles of the neck that maintain the vertical column which in turn supports the head are the sternocleidomastoid, thoracic, and semispinalis muscles. Torticollis manifests when the forces in these muscles are unbalanced due to a congenital or acquired problem within the spinal column, the muscles themselves, or as a result of abnormal neural inputs from a variety of sources including the vestibular apparatus.3 It is also a rare presenting sign of a psychiatric disorder.2,3
Ocular torticollis arises from disturbances in the input from the afferent visual pathway, ocular motor nerves, or the vestibular apparatus. Any of these disorders leads to alterations in the inputs to the neck muscles. In ocular torticollis, the abnormal posture is adopted for the following reasons:2,5–9
2. To maintain single binocular vision.
3. To center a narrowed visual field with respect to the body.
Torticollis due to an ocular problem that persists long-term can lead to a secondary musculoskeletal torticollis and even scoliosis.3–5,9–13 Torticollis is not a diagnosis, but a sign of an underlying disorder:3 a cause must be sought. The assessment in a child is often multidisciplinary, involving pediatricians, orthopedic surgeons, neurologists, and physiotherapists.3,14 It is common for an ophthalmologist to be consulted to rule out ocular causes for torticollis.
General categories of head postures
By orientation (Fig. 81.1)
Torticollis can involve rotation of the head around any of the three main axes. These include:
1. The vertical axis: the head is rotated to one side or the other away from the primary gaze.
2. The horizontal axis: the chin is elevated or depressed relative to the primary position.
3. The anteroposterior axis: the head is tilted to one or the other shoulder.
By onset
Most cases of childhood torticollis are not seen at birth but within a few months. There are cases of true congenital torticollis due to muscular or skeletal anomalies.1,3,14 Ocular torticollis almost never presents within the first few weeks of life. Trauma must be ruled out as a cause of any acquired AHP, whether as a result of damage to the neck or due to disruption of eye muscle balance.3
By timing
An AHP can be paroxysmal or persistent. It can be temporary in transient diseases, such as otitis media or benign paroxysmal torticollis of infancy. It can be constant, as with congenital nystagmus with an eccentric null zone or with restrictive strabismus. The head posture can be consistent in its orientation, as occurs in cases of superior oblique muscle paresis (see Chapter 83) and congenital nystagmus (see Chapter 89) or it may constantly change, as PAN.
Non-ocular causes of head postures (Box 81.1)
Congenital disorders
Muscular causes
Congenital muscular torticollis
Congenital muscular torticollis (CMT) is the most common type of congenital torticollis: it occurs in 0.4% of newborns. It manifests within 2 to 6 weeks of age, and in many cases there is a painless, discrete “fibroma” on one side of the neck adjacent to the sternocleidomastoid muscle.1,3,5,14–16 The infant develops a head tilt to the side of the involved muscle, with a forward flexion. The mass resolves with time over several months.
As the neck and facial bones enlarge, the fibrotic sternocleidomastoid muscle may fail to elongate properly. As a result, CMT can lead to various deformities including hemifacial hypoplasia, plagiocephaly, and compensatory thoracic scoliosis: these changes can be arrested by early intervention with passive physiotherapy.1,2,15 In a minority, surgery is needed.1,15
Postural torticollis
The head posture is evident shortly after birth but it is not associated with any mass in the sternocleidomastoid muscle. It may result from an abnormal fetal position. It is usually transient, although some cases require physiotherapy early in childhood to release muscle stiffness.1,16
Skeletal or osseous causes
Abnormalities in the cranial junction or cervical spine, including atlantoaxial rotatory displacement and odontoid hypoplasia, can lead to chronic torticollis.1,3
The Klippel-Feil syndrome can lead to torticollis as a result of the associated cervical vertebral anomalies, including congenital vertebral fusion and hemivertebrae, which can lead to reduced neck motion. Sprengel’s deformity is seen in 30% of Klippel-Feil cases. It is characterized by an elevated scapula with limited shoulder movement, and is associated with scoliosis, renal anomalies, and an omovertebral bone.1,3
There are several clinical syndromes that place the child at high risk of cervical spine instability as a result of congenital laxity of ligaments or abnormalities of their vertebral bodies. These include Down’s syndrome, mucopolysaccharidoses (see Chapter 62), and osteogenesis imperfecta.1
Acquired disorders
The acquired causes are divided into traumatic and non-traumatic. Trauma must be considered in any child with torticollis.1,16,17
Traumatic causes
Trauma can damage bones, ligaments, or muscle or soft tissue. The most common trauma affecting the neck involves rotatory subluxation of the atlantoaxial joint or subluxation of C2 and C3.1,3,16,17 Fractures of the scapula or clavicle can lead to AHPs.3 There is pain and limitation of movement, although there may be little or no neurologic deficit.3 Ligament injuries are less common, but they can be associated with severe neurologic complications, especially if the transverse ligament is ruptured.16 Direct trauma to the neck can lead to hematomas or tearing of muscle fibers, especially the sternocleidomastoid or the posterior capitis.3,16
Non-traumatic causes
Skeletal or osseous torticollis
Bone erosion in the cranial junction or cervical spine can lead to chronic torticollis. Erosion can arise from inflammation due to osteomyelitis, rheumatoid arthritis, or tuberculosis or from tumors. It leads to rotatory subluxation or anterior dislocation.1,3,16
Atlantoaxial rotatory displacement can arise from excessive transverse ligament laxity following a local infection, especially cervical adenitis or a retropharyngeal abscess.1,16 It can also arise from intrinsic changes in the ligament, e.g. in patients on prolonged systemic steroids.3 Most cases resolve spontaneously or once an underlying cause is reversed. A minority require immobilization or cervical traction.1,3
Postural torticollis
Rarely, torticollis can be produced by prolonged maintenance of the head in an awkward position that causes undue neck strain. Usually seen in older children, it develops gradually with permanent changes in the neck muscles.3
Neurologic
Posterior fossa and spinal pathology
Torticollis may be the only sign of a spinal cord or central nervous system anomaly or neoplasm.18 Acquired torticollis may be the presenting sign of syringomyelia leading to scoliosis and hyperhidrosis. Torticollis has also been described with colloid cysts of the third ventricle and with tumors of the posterior fossa, including ependymomas and hemangioblastomas.3 Astrocytomas of the cervicomedullary junction can stretch the meninges and cause neck muscle spasms on attempted passive flexion of the head, especially in young children.1 Tumors in the lower brain stem and cervical spine can cause anomalous head postures in young children, usually head tilts or chin-up postures. Torticollis accompanied by hyperactive tendon reflexes or extensor plantar responses may indicate a cervical cord disturbance, indicating the need for radiologic examination.2
The Arnold-Chiari malformation, in which there is a downward displacement of the cerebellar tonsils in the cervical canal, can lead to symptoms and signs including scoliosis, headache, and neck pain with torticollis.1 There is a triad of photophobia, epiphora, and torticollis associated with posterior fossa lesions. The postulated mechanism for the torticollis is irritation of the vestibular nuclear complex, herniation of the tonsils, oblique muscle paresis, or a combination of these.19,20
Dystonia
Spasmodic torticollis is a form of dystonia of the facial and cervical muscles that results from neurologic diseases or as an effect of medications that affect the basal ganglia. Loss of interneuron inhibition is a factor.1,2,5 Affected patients show sustained muscle contractions with repetitive movements and AHPs.
Spasmodic torticollis in children can be a reaction to psychiatric medications such as phenothiazine. It may be accompanied by other dystonic reactions such as trismus and oculogyric crises.2 Idiopathic spasmodic torticollis in children is rare; it often progresses from a focal dystonia to a more generalized disorder.1 Two other conditions that can present in the first two years of life are benign paroxysmal dystonia of infancy and paroxysmal choreoathetosis.2,3
Infections
AHPs, usually head tilts, have been reported with acute bacterial meningitis; the mechanism may be involvement of the cranial nerves, especially the fourth cranial nerve.2,5 Torticollis can also follow encephalitis with damage to the basal ganglia.3 It can occur after systemic infections including scarlet fever, measles, influenza, poliomyelitis, and diphtheria, or from postinfectious neuritis or as a result of osteomyelitis from a cervical abscess.3
Otolaryngologic
Nasopharyngeal torticollis
Non-traumatic acute torticollis in children commonly results from inflammations and infections of the the pharynx, tonsils, sinuses, mastoids, and the ears.16 The deep cervical lymph nodes are frequently enlarged and the sternocleidomastoid muscle becomes painful due to spasm,1,3,16 a condition termed Grisel’s syndrome.16
The head postures seen with otitis media may be due to labyrinthine disturbances.3 Retrotonsillar and retropharyngeal abscesses can lead to torticollis. A presumed cause is fluid accumulation between the ring of C1 and the odontoid bone.3,16
Benign paroxysmal torticollis of infancy
This consists of recurrent attacks of head tilting often accompanied by vomiting, pallor, and agitation21 in female infants. When the child begins to walk there is ataxia and older children may have headaches or vertigo.1,2,16,21 It is considered a migraine variant that affects the vestibular system. There is often a strong family history of migraine. This tends to subside over several months or years.2,16,21
Deafness
In infants an intermittent, unilateral, recurring face turn may be the presenting sign of a unilateral hearing deficit.2,3
Miscellaneous causes
Gastroenterologic
Hiatus hernia and gastroesophageal reflux can be seen in children, usually those with cerebral palsy. This combination can lead to intermittent neck extensions or head tilts to decrease the amount of reflux, known as Sandifer’s syndrome.1,2,4,5,13,16 Such infants with this rarely present with vomiting.1,2,16 Antireflux treatment can help. Abnormal neck postures have also been described in infants with pyloric stenosis.3
Metabolic disorders
Torticollis with dystonia and dyskinesia occurs in glutaric aciduria. Affected children may also have severe motor and language deficits and global developmental delays.1,3
Pharmacologic
There are a number of drugs that cause torticollis including the phenothiazines and metoclopramide.1,3
Ocular causes of head postures
General considerations
Children adopt head postures with several ocular conditions. When the child derives a demonstrable advantage by adopting the head position it is more correctly termed a compensatory head posture22,23 and the ophthalmologist’s goal is to determine an ocular cause. If there is an underlying ocular cause, treatment can eliminate or reduce the problem and restore a normal head posture.
1. An untreated ocular cause can lead to changes in the neck muscles and produce a secondary torticollis,4,9,10,14 which may persist even if the underlying ocular situation is rectified.
2. A child with incomitant strabismus may adopt a compensatory posture to maintain fusion. If the posture is difficult to sustain, the child may assume a more normal position which creates a heterotropia with loss of fusion, suppression, and amblyopia.2
3. Some ocular head tilts early in childhood can be associated with changes in the facial bones and even plagiocephaly. The facial bony changes may be secondary to, or coincident with, the head position. The bony alterations can be prevented by early treatment of the eye disorder.9,10–12
4. The binocular visual acuity of a child with a compensatory posture may not be optimal in the adopted position, especially if nystagmus is the cause (see Chapter 89). Eye muscle surgery for the head posture may improve the binocular acuity.13,23–26
Compensatory head postures have four advantages.4,22 They serve to:
Optimize visual acuity
Children adopt a compensatory posture either to optimize their binocular visual acuity or, if unable to maintain that, to maximize vision in the fixing eye.2,6,22
Examples in the first category include infantile nystagmus (see Chapter 89) and ptosis (see Chapter 19). In the case of infantile nystagmus, the vision is best because the nystagmus intensity (amplitude × frequency) is least or else the fovation times within the waveforms are maximized in the AHP.23,24,26 The AHPs of spasmus nutans and ocular motor apraxia (saccadic initiation failure) fall into this category.4,6,23,26
The second category includes significant refractive errors (especially astigmatism), manifest latent nystagmus in a monocular patient, severe restrictive strabismus, and infantile esotropia with cross fixation. It also includes cases of eccentric fixation associated with macular heterotopia and head tilts adopted in order to reorient the retinal meridians in the presence of cyclotropia.6,27
Maintain binocularity
Many forms of incomitant strabismus have a gaze position featuring zero, or minimal, heterotropia and where fusion is maintained. Usually the posture is adopted to gain the benefit of bifoveal fusion, but it can also achieve anomalous retinal correspondence.9 The causes can be subdivided into horizontal incomitance (such as sixth nerve paresis; see Chapter 83), Duane’s syndrome with esotropia (see Chapter 82), and oblique muscle paresis (see Chapter 83) and vertical incomitance (such as monocular elevation deficits and “A” and “V” pattern strabismus; see Chapter 80).
The causes in each plane can also be grouped under innervational and mechanical causes.28 Innervational problems include both underaction of muscles (e.g. muscle paresis and myasthenia; see Chapter 83) and excessive innervation of muscles (e.g. overaction of oblique muscles; see Chapter 80). Mechanical problems can affect any of the structures within the orbit such as bony abnormalities (e.g. orbit fractures), muscle disorders (e.g. thyroid orbitopathy, Brown’s syndrome and congenital cranial dysinnervation disorders), soft tissue diseases (e.g. pseudotumors), and neoplasms in the orbit.
Center the field of binocular vision
A child with congenital homonymous hemianopia may turn their faces to the hemianopic field when they fixate to centralize the intact visual field with the body.2,9,29,30 Altitudinal field defects may also include chin-up or chin-down head postures.2 Finally, monocular patients may turn slightly to the blind side to maximize their panorama of vision.9
