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Chiarimalformation
Chiari malformations are a group of hindbrain abnormalities classified into four types, ranging from Chiari I with tonsillar herniation to Chiari IV characterized by cerebellar hypoplasia. The document discusses associated anomalies, clinical features, and management approaches for each type, emphasizing diagnostic imaging and surgical interventions for symptomatic patients. Key considerations for surgical procedures include tonsillar descent, the presence of syrinx, and potential postoperative complications.
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Chiarimalformation
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- 2. Introductio n• These comprisea group of abnormalities involving the rhombencephalon (hindbrain) and the contents of the CV junction. • Presentlythere is no consensus regarding the precise definition, classification, etiology and the surgical management . • Series of hindbrain anomalies • Four types•
- 3. Definitions of Chiari malformations•Chiari type I tonsillar herniation below foramen magnum. no associated brainstem herniation or supratentorial anomalies. hydrocephalus uncommon. • Chiari type II caudal herniation of brainstem, cerebellar vermis, and fourth ventricles. associated with myelomeningocele & intracranial anomalies. hydrocephalus & syringohydromyelia common • Chiari type III occipital encephalocele with many of same intracranial anomalies seen with type II malformation. • Chiari type IV hypoplasia / aplasia of cerebellum with no hindbrain herniation
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- 7. Associated anomalies – Chiaril• Skull – Basilar skull and cv junction anomalies (50%) • Underdevelopment of supraocciput and exocciput • Shortening of supraocciput • Shorter clivus • Smaller and shallow posterior fossa • Empty sella • Platybasia • Basilar impression • Midline occipital keel • Accessory occipital condyle
- 8. Associated anomalies – Chiaril • Spine – Klippel-Feil deformity – Atlantoaxial assimilation – Retroflexion of odontoid process – Thickening of ligamentum flavum – Scoliosis
- 9. Associated anomalies – Chiaril • Ventricle and cistern – Hydrocephalus (3-10%) – Elongated 4th ventricle – Retrocerebellar CSF space are obliterated or diminished
- 10. Associated anomalies – Chiaril • Meninges -- Elevated slope of tentorium – Thickening of arachnoid at foramen magnum – Constricting dural bands at level of foramen magnum and posterior arch of atlas – Veils of arachnoid that obstruct fourth ventricular outlet
- 11. Associated anomalies – Chiaril • Spinal cord – Syrinx (50- 75%)
- 12. Associated anomalies – Chiaril • Brain – Elongated midbrain, pons and medulla – Medullary kinking or flattening – Tonsils- peg like.
- 13. CHIARI MALFORMATION II - Caudalherniationof brainstem, cerebellar vermis, and fourth ventricles. - associated with myelomeningocele & intracranial anomalies. - hydrocephalus& syringohydromyelia common
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- 15. Associated anomalies – Chiarill• Skull – Craniolcunia or luckenschadel- copper beaten appearance of calvaria – Anterior scalloped frontal bone (lemon sign ) – Scalloping of pterous and jugular tubercle – Enlarged FM – Notched opisthion – Elongated clivus with concavity – Lower inion – Basilar impression – Assimilation of atlas
- 16. Chiari IISupratentorial pathology• Luckenschadelor Lacunar skull – result of abnormal radial growth of the skull, seen in upto 85% of cases – Focal areas of cortical thinning and scalloped appearance of the skull – most prominent at birth, may resolve with age – not a result of raised ICP and hydrocephalus
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- 19. Genetics of Chiari • Familialoccurrence • Concordance in twins and triplets • Association with other genetic disorder – Spondyloepiphyseal dysplasia tarda – Hadelu-Cheney syndrome – Klippel-Fiel syndrome – achondroplasia
- 20. Chiari III• herniation ofbrainstem and cerebellum into a posterior encephalocoel. • Very rare; most severe form. Management difficult. • Differentiate from cervical myelomeningocoel. • Severe neurological, developmental and cranial nerve defects, seizures and respiratory insufficiency. • Treatment- well planned encephalocoel closure
- 21. CHIARI 3: occipitalencephalocele with
- 22. Chiari IV• cerebellar hypoplasiaor aplasia(1896). Post fossasizenormal. • No hindbrain herniation. • Tentorium cerebelli also hypoplastic.
- 23. CHIARI 4 :Cerebellarhypoplasia/
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- 25. Chiari I• HEADACHE Most commonsymptom (81%) Sub occipital Radiation to vertex / neck / retro- bulbar Heavy crushing / pressure like ↑ed by physical exertion, Valsalva maneuver, head dependency and sudden changes In position
- 26. Chiari I• Spinal cord/syrinx – sensory • Numbness: initial complaint, asymmetric, hands/arms • Dissociated sensory loss: loss of pain and temp, preserved touch and JPS • Dysesthesia and proprioception disturbances – advanced stage • Deep and boring/ itching/ burning • C2 dysesthesia • Interscapular pain • All pain exacerbated by cough and sneeze • Valsalva or severe cough may alter findings • Charcot joints: <5% of patients
- 27. Chiari I• Spinal cord/syrinx – Motor: • Difficulty in performing fine motor tasks in UL • Weakness of hand and/or arm • Wasting – distal and proximal • Fasciculations • Absent DTRs • UMN lower extremities • Horners’ – complete or partial • Bowel and bladder control normal • Occasionally LMN in lower extremities
- 28. Chiari I• Brain stem/CSF flow/ FM – Cough headache – Neck and arm pain – non dermatomal “deep and boring” – Down beat nystagmus – Hoarse voice – Palatal dysfunction – Tong– fasciculations/ atrophy – Dysphagia – Hiccups – Severe snoring – Respiratory dysrhythmias – Facial numbness – Drop attacks – Dysarthria
- 29. Chiari I• Cerebella r: – Nystagmus: –Ataxia – Dysmetria
- 30. Chiari II• Commonly presentsin infancy, childhood and adolescence • May stabilize or improve after 6 to 12mths • Risk of apneic attacks, dysphagia with aspiration pneumonia, life threatening vocal cord paralysis • Leading cause of death in treated myelodysplastics within first 2 yrs of life
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- 32. Chiari II• Brain stem –Nystagmus. – Poor sucking/ dysphagia/ aspiration – Arching of head/ fixed retrocollis/ ophistotonus – Apneic spells – cyanosis/anoxic seizures – exhausted- sleeps – Vocal cord abductor palsy – VII nerve paresis – Dysconjugate eye movements – Mirror movements
- 33. Chiari II• Spinal cord/syrinx – Spasticity of upper extremities. – Weakness of lower extremities. – Persistent cortical thumb. – Suspended dissociated sensory loss. – Upper extremity weakness and wasting of hand muscles. – Scoliosis.
- 34. Chiari II• Cerebellar: – Nystagmus:horizontal or rotary – Appendicular ataxia: “falls so much”, gait changes – Dysmetria: inability to feed himself
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- 36. Establishment of Diagnosis • Xray CVJ and cervical spine... • Computed Tomography Scanning (CT) • Magnetic Resonance Imaging (MRI)
- 37. MR I • Investigation ofchoice to assess the degree of tonsillar descent • T2 weighted saggital MRI of the spine... • Helps to screen the whole of the spine and brain for any other associated anomaly of the neuraxis or presence of hydrocephalus • Septations and flow voids within the syrinx can be seen
- 38. Indications for surgical Intervention•Progressive neurological deficit • Progressive enlargement of syrinx.
- 41. PFD vs PFDD• Durhamand Fjeld-Olenec : meta-analysis of studies that directly compare cohorts of pediatric patients who underwent PFD with PFDD. • Patients who undergo duraplasty are less likely to require reoperation (2.1% vs. 12.6%) for persistent or recurrent symptoms but are more likely to suffer CSF- related complications • No statistical difference in clinical outcomes between the two groups, specifically with regard to symptom improvement and syringomyelia
- 42. • clinical improvementwere 65% in the PFD patients and 79% in the PFDD patients • Syrinx resolution :56% in the PFD patients and 87% in those undergoing PFDD.
- 44. Selection of Surgical Procedure •Depends on whether chiari is associated with syrinx or not. • Also on the type and degress of tonsillar descent. • The key is to decompress the posterior fossa and CVJ adequately, and to establish normal CSF flow across the region of formen magnum.
- 45. Various procedures adopted • FMDalone • FMD with lax duroplasty • FMD with arachnoid adhesiolysis and lax duroplasty • FMD with tonsillar resection, and lax duraplasty • FMD with any of the above and additional removal of C2. FMD = Suboccipital craniectomy encompassing the foramen magnum rim and C1 posterior arch
- 46. Additional procedures for associated problems•Hydrocephalus – VP shunt – ETV (Missimi et al - NS 2011) • CVJ instability – Posterior fusion
- 47. Surgical Technique • Bony decompression •Dural procedures • Arachnoid handling • Dealing with the tonsils
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- 49. Skin Incision • Extent: – Justbelow inion – Just past the C2 spine
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- 54. Bleeding at durotomy • Cerebellardura may have venous lakes • Circular or occipital sinus may bleed profusely • Control – Proceed slowly – Bipolar – Metal Clips – Figure of 8 stiches
- 55. Intradural exploration • Arachnoid opening –Under magnification – Midline – Avoid adherant PICA – Only sharp dissection
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- 57. Wound closure • Layered closure – Muscle –Facia – Subcuticular – Skin
- 58. Postoperative complications • Early – CSFLeak • Address HCP • Resuture • Lumbar drain – Meningitis – Infective / Chemical • Non autologous graft • Dura not closed • Meticulous and clean procedure
- 59. Postoperative Complications • Early – Lowercranial nerve dysfunction – Brainstem dysfuctions – Hematoma
- 60. Postoperative Complications • Late –Symptom recurrence •Occur after initial improvement • Due to: – New or enlarging syrinx – CSF obstruction due to scarring – Cerebellar ptosis –Pain
- 61. Recurrent or UnresolvedChiari Failed procedure • Causes: – Inadequate decompression • Bony • Soft tissue – Reformation of arachnoid scars – Lack of CSF flow normalization despite adquate soft tissue and bony decompression • Management – Revision surgery – Shunting of the syrinx
- 62. Follow up• Chiari I •Pts without a syrinx: follow up at 1, 6 & 12 months, then every 12 to 24 months ;no need of repeat imaging (if there is symptomatic improvement) • Pts with syrinx: follow up MRI in 6 to 12 months.No further imaging if symptoms improve or syrinx decreases in size significantly.
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