Diagnosis
Diagnosis is made through a combination of patient history, neurological examination, and medical imaging. Magnetic resonance imaging (MRI) is considered the preferred imaging modality for Chiari malformation. The MRI visualizes neural tissue such as the cerebellar tonsils and spinal cord as well as bone and other soft tissues. CT and CT myelography are other options and were used prior to the advent of MRI, unfortunately the resolution of CT based modalities do not characterize syringomyelia and other neural abnormalities as well.By convention, the cerebellar tonsil position is measured relative to the basion-opisthion line, using sagittal T1 MRI images or sagittal CT images. The selected cutoff distance for abnormal tonsil position is somewhat arbitrary, as not every person will be symptomatic at a certain amount of tonsil displacement, and the probability of symptoms and syrinx increases with greater displacement; however, greater than 5 mm is the most frequently cited cutoff number, though some consider 3–5 mm to be "borderline,"; pathological signs and syrinx may occur beyond that distance. One study showed little difference in cerebellar tonsil position between standard recumbent MRI and upright MRI for patients without a history of whiplash injury. Neuroradiological investigation is used to first rule out any intracranial condition that could be responsible for tonsillar herniation. Neuroradiological diagnostics evaluate the severity of crowding of the neural structures within the posterior cranial fossa and their pressure against the foramen magnum.
Weak crying
Facial weakness
Aspiration
Headaches aggravated by Valsalva maneuvers, such as yawning, laughing, crying, coughing, sneezing or straining, bending over, or getting up suddenly
Tinnitus (ringing in the ears)
Lhermittes sign (electrical sensation that runs down the back and into the limbs)
Vertigo (dizziness)
Nausea
Schmahmann syndrome
Nystagmus (irregular eye movements; typically, so-called "downbeat nystagmus")
Facial pain
Muscle weakness
Impaired gag reflex
Dysphagia (difficulty swallowing)
Restless leg syndrome
Sleep apnea
Sleep disorders
Impaired coordination
Severe cases may develop all the symptoms and signs of a bulbar palsy
Paralysis due to pressure at the cervico-medullary junction may progress in a so-called "clockwise" fashion, affecting the right arm, then the right leg, then the left leg, and finally the left arm; or the opposite way around. Papilledema on fundoscopic exam due to Increased intracranial pressure
Pupillary dilation
Dysautonomia: tachycardia (rapid heart), syncope (fainting), polydipsia (extreme thirst), chronic fatigue
Apnea: Sudden pause of breathing, usually during sleep. Opisthotonos: Spasm of the head which causes head to arch backwards. More common in infants than adults. StridorThe blockage of cerebrospinal fluid (CSF) flow may also cause a syrinx to form, eventually leading to syringomyelia. Central cord symptoms such as hand weakness, dissociated sensory loss, and, in severe cases, paralysis may occur. Syringomyelia
Syringomyelia is a chronic progressive degenerative disorder characterized by a fluid-filled cyst located in the spinal cord. Its symptoms include pain, weakness, numbness, and stiffness in the back, shoulders, arms or legs. Other symptoms include headaches, the inability to feel changes in the temperature, sweating, sexual dysfunction, and loss of bowel and bladder control.