Bermans J. Iskandar Pediatric Neurosurgery University of Wisconsin, Madison ASAP Austin 2010

Chiari Type I u Tonsillar descent >5mm below the plane of the foramen magnum. u No associated brainstem herniation or supratentorial anomalies u Low frequency of hydrocephalus and syringomyelia Chiari Type II u Caudal descent of the vermis, brainstem, and fourth ventricle. u Associated with myelomeningocele and multiple brain anomalies u High frequency of hydrocephalus and syringohydromyelia Standard

Chiari Type IV u Hypoplasia or aplasia of the cerebellum Chiari Type III u Occipital encephalocele containing u Dysmorphic cerebellar and brainstem tissue Rare & Poor Prognosis

New & Controversial Chiari Zero u Idiopathic syringomyelia that responds to craniocervical decompression Chiari 1.5 u Descent of tonsils & medulla u Behaves like Chiari I JNS:Peds 2004JNS 1998

 Diagnosis made on MRI  Treatment: posterior fossa decompression.  If the syrinx does not resolve:  Re-explore the posterior fossa and expand the decompression  Consideration of subtle craniocervical instability  Consideration of benign intracranial hypertension  Consideration of shunting the syrinx directly

 8 year old boy with headaches  Syrinx  1 cm tonsillar descent

 30 year-old with 1.5 cm tonsillar descent and severe symptoms  Posterior fossa decompression fails  LP monitoring reveals elevated ICP  VP shunt  Symptoms resolve

 10 year-old who underwent serial lumbar punctures for a mild viral meningitis  Develops lower cranial nerve symptoms  MRI reveals new tonsillar herniation

 12 year-old with Chiari I, syringomyelia, and basilar invagination  Posterior fossa decompression  Symptoms and syrinx don’t resolve until craniocervical fusion a year later

 Likely Etiology  In utero CSF leak through the myelomeningocele opening, causing  caudal traction on brain structures  Clinical Presentation  Infants: usually asymptomatic  Children: signs of lower brainstem compression: stridor, apnea, dysphagia, aspiration

 Chiari II: leading cause of death in spina bifida patients in the recent past  30% of patients: brainstem symptoms by age 5 (1/3 of these die)  Most dangerous period: 2-3 months of age (sometimes up to 2 years)

 Current understanding  VP shunt malfunction most likely cause of deterioration, rather than the Chiari  Ventricle size may not change  Number of Chiari II decompressions has decreased significantly since more aggressive shunt revisions

 Fluid-filled cavity within the spinal cord  Other nomenclature  Hydromyelia  Syringohydromyelia  Spinal cord cyst

 Dissociated sensory loss  Central cord syndrome  Brainstem symptoms and signs  Scoliosis  Chronic pain

 Spinal MRI will show a dilated cavity with the same intensity of CSF.  A complete brain and spinal MRI with and without Gadolinium is needed to determine the primary pathology.  Cine MRI may also help in diagnosing abnormal CSF flow patterns. So far results have been conflicting.  Rarely, myelography may help to sort some of the more difficult cases.

 Asymptomatic patients with small syrinx cavity and no obvious etiology are best managed with watchful waiting and serial imaging  Large syrinx: Treat the cause of the syrinx, not the syrinx itself

 The syrinx may be the result  Tethered cord from the myelomenigocele repair scar  Chiari II malformation  Ventricular shunt malfunction.  Location of the syrinx within the spinal cord may help to dictate the treatment  Lumbar syrinx ??tethered cord release  Cervical syrinx ?? VP shunt revision  Check the shunt first!

 Diagnosis by MRI  Treatment: Tethered cord release  If syrinx is large, it is often drained at the same surgery

 Diagnosis made on MRI  Treatment: Dissection of the arachnoid scar (often difficult or impossible)  Goal: Reestablish normal CSF flow  Difficulties: If the arachnoiditis is so diffuse that it becomes impossible to achieve a good dissection, shunt the syrinx to the pleural or peritoneal cavities

 Post-traumatic syrinx is difficult to treat successfully  Possible causes  Arachnoiditis and blockage of flow causing expansion of the cord, or  Atrophy long term after cord contusion  Treatment: arachnoidal dissection, or syrinx shunt into the pleura or peritoneum

 Diagnosis made on MRI  High protein content  Treatment:  Tumor resection  It is rare to have to shunt the syrinx in these situations.

 In a large percentage of patients, the syrinx has no identifiable cause  Difficult to treat  If large, syrinx shunting  Rarely, posterior fossa decompression (Chiari zero)  It is so far impossible to predict which patient with idiopathic syringomyelia would respond to posterior fossa decompression

 Chiari decompression  Excellent outcome  Spina bifida  Excellent outcome when shunt is functional  Arachnoiditis  Focal – fair prognosis  Diffuse – poor, need to shunt the syrinx  Trauma  Poor outcome for syringomyelia and pain  Tumor:  Excellent outcome for syringomyelia  Overall Prognosis depends on tumor grade

 Standard basic definitions  Complicating factors: hydrocephalus, pseudotumor cerebri, instability, etc.  Treatment controversies  When to treat  What to do  When to do it  Goals: Recognize basic concepts; recognize controversial areas; be prepared to bring these points up with your physician