Transcript Chiari II Malformation - Spina Bifida Association

Chiari II Malformation
Mark S. Dias, MD, FAANS, FAAP
Departments of Neurosurgery and Pediatrics
Penn State Children’s Hospital
Chiari Malformation: History
• Hans Chiari
– Austrian Pathologist
– First described
syndrome in 1891
• Julius Arnold
– Colleague of Chiari’s
– Added a single case
report in 1894
– Students added his
name to syndrome
Development of the Cerebellum
Development of the Cerebelleum
• Explosive growth of
cerebellum
• Develops within the
posterior fossa
• Constrained by
surrounding structures –
dura, skull, incisura,
tentorium, and foramen
magnum
Development of the Cerebellum
• Vermis (midline)
• Tonsils (just lateral to
vermis)
INFERIOR
VERMIS
Development of the Chiari
Malformation
• Early cerebrospinal
fluid leak from back
• Smaller posterior fossa
• Subsequent growth of
cerebellum and
brainstem pushes both
structures up and
down
Development of the Chiari
Malformation
Chiari II Malformation:
What is it?
• Posterior fossa malformations
– Downward descent of inferior cerebellar vermis and
tonsils into spinal canal
– Downward displacement of brainstem and/or fourth
ventricle into spinal canal
• Produces medullary kink
– Upward displacement of superior cerebellar vermis
through incisura
– Small posterior fossa
– Low lying tentorium, enlarged incisura
– Tectal beaking
The Chiari Malformation:
What is it?
• Other brain malformations
– Enlarged massa intermedia of thalamus
– Abnormal or absent corpus callosum
– Stenogyria (multiple small gyri)
– Neuronal migration abnormalities
• Heterotopias
• Heterotaxias
Chiari II Malformation:
Presenting Features
• Anatomically present in nearly all
children with spina bifida
• Symptomatic in only 15-33%
• 90% develop symptoms and signs
during the first year of life
Chiari II Malformation:
Presenting Features
• Swallowing problems
74%
• Sensorimotor deficits
53%
• Pain (headache/neck)
44%
• Cerebellar problems
35%
• Eye movement problems
16%
Dias MS, McLone DG 1992
Chiari II Malformation:
Presenting Features
• Symptoms are very age dependent
– Infants: swallowing difficulties, choking,
breathing issues, stridor, disordered
breathing
– Older children: headaches, neck pain,
sensorimotor abnormalities, cerebellar
difficulties
Chiari II Malformation:
Presenting Features
• Stridor, weak or high pitched cry
– Vocal cord paralysis (one or both sides)
• Breathing stops (apnea) or is irregular
– May be obstructive or central
– Begins at end of cry, followed by low heart rate, blue
spell, coma, extension of arms/legs, seizures
– May occur even while on a ventilator!
Chiari II Malformation:
Presenting Features
• Swallowing difficulties
– Present in 59-71% of symptomatic infants
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Poor feeding, drooling, pooling of food
Worse with liquids than with solids
Coughing/sputtering
Regurgitation of foods up/out of nose
Chronic gastro-esophageal reflux (GERD)
Silent aspiration of liquids  pneumonia
lung scarring  heart failure
Chiari II Malformation:
Presenting Features
• Motor abnormalities
– Weakness, stiff or limp arms and/or legs
– Trunk unsteadiness/imbalance
– Poor truncal tone (slumping)
• Scoliosis
• Headache (occipital) and/or neck pain
Chiari II Malformation:
Management
• IT IS HYDROCEPHALUS OR SHUNT
MALFUNCTION UNTIL PROVEN
OTHERWISE!!!!
– Ultrasound, CT or MRI to check ventricle size
– Should compare with prior CT when doing well
– Remember that shunt malfunction can occur without
little or no significant changes
– Symptomatic Chiari malformation outside of infancy
is rare and almost always the result of shunt failure
Chiari II Malformation:
Management
• Chiari is almost always present, but is not
commonly symptomatic
– Decision to operate based on clinical symptoms
• MRI scan provides anatomical roadmap
– Extent of Chiari (vermian descent)
– Location of dural venous channels (bleeding)
– Syringomyelia, syringobulbia
Chiari II Malformation:
Management
• Dynamic swallow study
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Abnormalities of swallowing
Pooling of liquid in throat
Aspiration through vocal cords into trachea
Reflux
Nuclear medicine swallow evaluation
Vocal cord testing by ENT
Sleep study for sleep apnea
Manual muscle testing for muscle strength
Chiari II Malformation:
Management
• Suboccipital bony decompression and upper
cervical laminectomy
– Opened to the inferior end of the vermis
• Open dura and insert graft (duraplasty)
• Tonsillar removal
• Fourth ventricular stent/shunt
• Plugging of the obex
– Warning: OR picture coming up!
Vermis
Medulla
Chiari II Malformation:
Management
• When to Treat??
– Nearly every child with spina bifida has some
swallowing abnormalities
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More time to chew and swallow
Gags and vomits easily
Certain foods/textures not well tolerated
Solid foods worse than liquids
No aspiration/vocal cord palsy/apnea
– Most outgrow these problems over time
Chiari II Malformation:
Management
• When to Treat??
– Severe brainstem problems present at birth
• Apnea, vocal cord palsy, severely limp (hypotonia)
– May be due to a disorganized brainstem
– Outcomes generally poor when severe symptoms are
present at birth
– Reasonable outcomes obtained with early (< 5 days)
surgery to urgently decompress brainstem (Pollack)
– Overall mortality high (23-55%) in many series
Chiari II Malformation:
Management
• The ‘in-between’ child
– Progressive symptoms and/or signs
– Abnormal swallow studies
• Significant pooling of liquids, aspiration
– Vocal cord weakness or paralysis
– Apnea, stridor
– Persistent vomiting/poor weight gain
• These generally improve with surgery
• Might they also improve spontaneously over
time without surgery?
Chiari II Malformation:
Post-Operative Improvement
• Cerebellar Problems
100%
• Pain
94%
• Motor problems
83%
• Swallowing problems
– Most had vocal cord palsy
or apnea
53%
Dias MS, McLone DG 1992
Chiari II Malformation:
Conclusions
• Anatomically present in virtually all patients
but symptomatic in minority
• Usually presents in infancy - < 1 year
• Symptoms vary by age
• Treatment aimed first at SHUNT
• Posterior fossa/cervical decompression
• Outcome varies according to presenting
symptoms
Thank
you!