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[Dysphagia] OT: Chiari I malformation
- Subject: [Dysphagia] OT: Chiari I malformation
- From: firstname.lastname@example.org (Bonnie Heintskill)
- Date: Tue, 7 Oct 2003 09:25:22 -0500
I don't know if a lot of SLP's are familiar with this, but it does cause
speech and swallowing problems.
What is a Chiari I Malformation?
Chiari I malformation is a relatively simple anomaly that is unassociated
with other congenital brain malformations. In contrast to the Chiari II
malformation, in this disorder the vermis, fourth ventricle, and medulla are
normal or only minimally deformed. Elongated, pointed, "peglike" cerebellar
tonsils are displaced downward through the foramen magnum (the opening at
the bottom of the skull) into the upper cervical spinal canal. It is
believed that the bony skll posterior fossa is relatively too small for the
cerebellum, resulting in the tonsillar displacement.
Who gets Chiari I Malformations?
The average age at presentation is 41 years. Females slightly outnumber
males. It is seen in adolescents but occasionally is first encountered in
older individuals. Rarely it is seen in several members of one family.
What are the symptoms of Chiari I Malformation?
The most common symptom is pain, especially headache that is usually felt in
the back of the head, and is aggrevated by coughing and straining. Weakness
is also prominent, especially in the hands. Other symptoms include the
Pain: headache, neck pain, arm pain, leg pain
Loss of temperature sensation
Ringing in the ears (tinnitus)
How are Chiari I Malformations evaluated?
Plain x-rays: only 35% of skull or cervical spine x-rays are abnormal
MRI: this is the diagnostic test of choice. Easily shows the tonsillar
herniation, as well as syringomyelia which occurs in 20-30% of cases.
What other anomalies is Chiari I Malformation associated with?
Chiari I malformation is usually not associated with other brain anomalies.
However, spinal cord, skull base, and spine lesions are common in this
Spinal cord: Accumulation of cerebrospinal fluid (CSF) within the spinal
cord is a frequent finding in patients with Chiari I. Simple distention of
the ependymal-lined central canal is often termed hydromyelia. Dissection of
CSF through the ependyma to form cavitation within the substance of the
spinal cord is termed syringomyelia. The distinction between these two is
not possible based upon imaging studies and is probably not clinically
important.. Therefore the term syrinx, or syringomyelia, is used to describe
any abnormal accumulation of CSF within the spinal cord. A syrinx is present
in 20-40% of all patients with Chiari I.
Skull base and spine: Bony anomalies are seen in about one quarter of all
patients with Chiari I malformation and include atlantooccipital
assimilation, platybasia, basilar invagination, and fused cervical
How is Chiari I Malformation treated?
Surgical treatment is the treatment of choice for symptomatic Chiari I
malformation. Prior to treatment it must be clearly established that the
Chiari malformation is the cause of the symptoms. Once this is determined
the operative treatment consists of a suboccipital decompression. This
operation essentially involves removing bone in the region of the tonsillar
herniation (suboccipital) along with the posterior margin of the foramen
magnum and usually the posterior ring of the C1 vertebrae. Once the bone is
removed the dura mater is opened. The dura mater is then closed with a patch
dural graft placed so as to increase the space for the intradural
The main benefit of the surgical therapy is to arrest the progression of
symptoms. Severe complications following this treatment are rare. In
patients with syringomyelia, the spinal cord cyst generally becomes smaller
following suboccipital decompression.
Chiari II Malformation
What is a Chiari II Malformation?
Chiari II malformation is a complex anomaly with skull, dura, brain, spine,
and spinal cord manifestations. Although its exact etiology is unknown,
recent evidence suggests that the fetal neural folds fail to neurulate
completely, leaving a dorsal opening. Consequently, the developing spinal
cord walls do not appose properly and abnormal drainage of CSF through the
dehiscent neural tube into the amniotic cavity results. The primitive
ventricular system of the brain then collapses. This results in the
formation of an abnormally small posterior fossa. Subsequent development of
the cerebellum and brainstem within the abnormally small posterior fossa
leads to upward herniation and downward herniation of the cerebellar vermis
and brainstem through an enlarged foramen magnum into the upper cervical
This disorder is usually associated with myelomeningocele.
What are the major findings in Chiari II?
Downward dislocation of the cervicomedullary junction, pons, 4th ventricle
and medulla. Cerebellar tonsils located are located at or below the foramen
magnum. Other possible findings include:
"kinking" of the cervical cord
absence of the septum pellucidum
hydrocephalus is present in most patients
degeneration of the lower cervical nerve nuclei
How do patients with Chiari II present?
Findings are due to brain stem and lower cranial nerve dysfunction. Onset in
adulthood is rare. Most patients present in early childhood or in the
neonatal period. Findings include:
Swallowing difficulties: manifested as poor feeding, cyanosis (turning blue)
during feeding, nasal regurgitation, prolonged feeding time, pooling of
Apneic spells (periods when the child does not breathe)
Stridor: difficulty taking a breath, obstruction to taking a breath
Aspiration: feeding material taken into the lungs
Nystagmus (horizontally beating eyes)
Weak or absent cry
What is the treatment for Chiari II Malformation?
Insert CSF shunt for hydrocephalus (or check function of existing shunt). If
patient has swallowing difficulty, stridor or apneic spells occur, urgent
posterior fossa decompression is recommended.
What is the outcome with Chiari II Malformations?
68% have complete or near complete resolution of symptoms, 12% had mild to
moderate residual deficits, and 20% had no improvement (in general neonates
fare worse than older children).
The World Arnold Chiari Malformation Association