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 Sensorimotor deficits Pain (headache/neck) Cerebellar problems Eye movement problems 74% 53% 44% 35% 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 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) –S yringomyelia, syringobulbia

Chiari II Malformation: Management Dynamic swallow study –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 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 Pain Motor problems Swallowing problems –Most had vocal cord palsy or apnea 100% 94% 83% 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

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