Findings are due to brain stem and lower cranial nerve dysfunction. Onset of symptoms are less likely to be present during adulthood in most patients. Younger children generally have a substantially different presentation of clinical symptoms from older children. Younger children are more likely to have a more rapid neurological degeneration with profound brain stem dysfunction over several days. * Neurogenic dysphagia: Difficulty swallowing. Seen by poor feeding in patient. * Cyanosis: Bluish discoloration of skin while feeding. * 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) * Lhermitte's 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. * Stridor The 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. It is usually seen in the cervical region but can extend into the medulla oblongata and pons or it can reach downward into the thoracic or lumbar segments. Syringomyelia is often associated with type I<unk>  and is commonly seen between the C-4 and C-6 levels. The exact development of syringomyelia is unknown but many theories suggest that the herniated tonsils in type I<unk> s cause a "plug" to form, which does not allow an outlet of CSF from the brain to the spinal canal. Syringomyelia is present in 25% of patients with type I<unk> s.
Chiari malformation
Glial tumor
Central nervous system cyst
Dandy–Walker malformation
Arachnoid cyst
Subdural hygroma
Cavernous venous malformation
Meningism