Basilar impression is a condition resulting from anomalies at the base of the skull and vertebrae, which lead to a short neck, headache, neck pain, and cranial nerve palsies due to compression of the cranial nerves Many congenital conditions, including Klippel–Feil syndrome, achondroplasia, and neurofibromatosis, may cause basilar impression Commonly associated with basilar impression is occipitocervical synostosis, a condition in which fibrous or bony connections between the base of the skull and the atlas cause neck pain, torticollis, high scapula, and neurologic symptoms Atlantoaxial Instability Several congenital conditions may be associated with atlantoaxial instability and may predispose the patient to cervical subluxation In addition to Down, Marfan, and Klippel–Feil syndromes, these include other skeletal dysplasias and os odontoideum (aplasia or hypoplasia of the odontoid process of the axis) Morquio syndrome is a mucopolysaccharidosis resulting in flattening of the vertebrae and multiple skeletal dysplasias In this syndrome, the odontoid is underdeveloped and may lead to atlantoaxial subluxation Miscellaneous Causes of Neck Stiffness Head tilt, neck stiffness, and/or torticollis have been reported in other conditions, some of which are life threatening and others generally benign Ophthalmologic, Neurologic, and/or Vestibular Causes Head tilt or neck malposition may result from abnormalities of vision (e.g., strabismus, cranial nerve palsies, extraocular muscle palsies, refractive errors) or the vestibular apparatus The child attempts to correct for the disturbance through changes in neck position Careful ophthalmologic and neurologic examinations of the child with head tilt are necessary to exclude these possibilities Torticollis has also been reported in patients with migraine headaches Myasthenia Gravis Patients with myasthenia gravis may develop torticollis, although ptosis, impairment of extraocular muscular movement, and other cranial nerve palsies are generally earlier signs Guillain–Barré Syndrome Neck stiffness has been reported in children with Guillain–Barré syndrome Neck stiffness in this condition is seen in association with generalized motor weakness and areflexia Idiopathic Intracranial Hypertension Stiff neck and torticollis have also been reported in children with idiopathic intracranial hypertension, also known as