The availability of MR scanning has lead to an increasingly earlier diagnosis of the Chiari Malformation. The noninvasive nature of this test along with its superior imaging of the base of the brain has lead to its increase use in children with such relatively nonspecific complaints of headache and curvature of the spine. Now the condition is frequently diagnosed before the onset of frank neurologic dysfunction. The onset of symptoms referable to a Chiari Malformation is typically subtle and evolve slowly.
Consequently, it is not unusual for the condition to be diagnosed after months or years of problems which in retrospect are due to the malformation. The symptoms attributable to the malformation will vary according to the patient's age, the degree of displacement of structures downward, the presence of associated bony anomalies of the spine and the presence of hydromyelia.
The most frequent symptom groupings include:
v Headache, pain at base of skull/upper neck
v Progressive scoliosis (curvature of the spine)
v Cerebellar dysfunction (difficulty with balance, coordination, dysequilbrium, low muscle tone)
Compression Of The Lower Brainstem May Cause:
v Alteration of voice
v Frequent respiratory tract infections
v Coughing when swallowing foods and fluids
Compression Of The Spinal Cord Or Distention Due To Accumulating Fluid (Hydromyelia):
v Suspended alteration of sensation (e.g., arms are effected but legs not)
v Central cord disturbance (injury to central part of spinal cord with resultant weakness greater in arms than legs)
v Spasticity (abnormally high muscle tone or tightness, especially with movement of the muscle)
Anomalies of the base of the skull and spine are seen in 30-50% of patients with the Chiari Malformation, Type 1. These anomalies include:
v Basilar impression (compression of the upper part of the spine into the base of the skull with resultant compression of the brainstem)
v Atlanto-occipital fusion (bony union of the first level of the spine to the base of the skull)
v Atlanto-axial assimilation (partial bony union of the first and second levels of the spine)
v Klippel-Feil deformity (congenital union or fusion of levels of the spine within the neck with possible associated maldevelopment of levels of the neck's spine)
v Cervical spina bifida occulta (bony defect in a the posterior part of the spine)
v Scoliosis - commonly seen when hydromyelia exists (16-80% of patients), especially in children with immature spines.
v Postural and cough headaches (majority of cases)
v Dull, chronic headache involving back of head or neck
v Paroxysmal, severe headache associated with a valsalva maneuver (cough headache)
v Visual disturbances from nystagmus (jerking of eyes when looking to right or left),
v Oscillopsia (vertical bobbing of eyes) or diplopia (double vision)
v Spasticity (muscle stiffness)
v Sensorimotor deficits (abnormal body sensation and/or muscle strength)
v Ataxia (difficulty with balance and coordination)
v Dysarthria (difficulty talking)
v Dysphagia (difficulty swallowing)
Note:
There have been reported cases of children with previously undiagnosed Chiari Malformations sustaining injuries to the spinal cord with no obvious abnormality in the x-rays of their spine. The evaluation of children who have sustained a spinal cord injury should include a MR scan of their spinal cord that includes imaging of the base of the brain to rule out a Chiari Malformation.
