Chiari malformation

Chiari Malformations with all theories & management

1. CHIARI MALFORMATIONS Dr. Sourabh Jain Medical college & Hospital Trivandrum

2. Introduction These comprise a group of abnormalities involving the rhombencephalon (hindbrain) and the contents of the CV junction. Presently there is no consensus regarding the precise definition, classification, etiology and the surgical management . Series of hindbrain anomalies Four types No anatomical or embryological correlation between them

3. History 1883, John Cleland (Professor of anatomy in Glasgow, Scotland) - described hindbrain hernia in a child with myelodysplasia. 1891 and 1896, Hans Chiari- (Professor of Pathology at German University, Prague, Czechoslovakia) analyzed data from >40 postmortem examinations of patients with hindbrain malformations. Chiari malformations I, II and III were coined in the earlier work and Chiari malformation IV was added in 1896 publication.

4. History 1894, Julius A. Arnold(Professor of Pathology at Heidelberg, Germany)- described a single myelodysplastic patient with associated hindbrain herniation . Schwalbe & Gerdig included Arnold name in the eponym & designated it ARNOLD –CHIARI malformation.

5. Definitions of Chiari malformations Chiari type I tonsillar herniation below foramen magnum. no associated brainstem herniation or supratentorial anomalies. hydrocephalus uncommon. Chiari type II / ACM 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

6. Transitional forms of Chiari malformations Chiari type 1.5 tonsillar herniation as seen in Chiari I with addition of an elongated brainstem and fourth ventricle. ( Iskandar B,1999 ) Chiari type 0 syringohydromyelia with no evidence of hindbrain herniation. All of these improved, clinically and radiographically, in the syrinx following posterior fossa decompression. Functional disturbances of CSF flow across the CV junction. At surgery arachnoidal veils and adhesions obstructing the Foramen of Magendie with crowding of tissue at the Foramen of magnum (Iskandar B. J Neurosurgery 89:212-216,1998)

7. CHIARI 0: Minimal or no herniation+ Clinical features of Chiari 1 + CSF equilibrium changes. Responds to decompression.

8. CHIARI 1.5 Tonsillar herniation + elongation of brainstem and 4 th ventricle.

9. Chiari I definition? Tonsilar herniation below foramen magnum. Extent of descent below FM ? Analysis of 800 MRI(95 patients-82 controls, 13 patients) Asymptomatic patient tonsillar herniation <3mm Border line 3-5 mm Symptomatic >5mm (diagnosis of Chiari malformation) In most cases of Chiari II- saggital diameter of foramen magnum >42mm ( Aboulezz et al. Comput Assist Tomogr . 9:1033-1036,1985) Analysis of 200 controls + 25 pt -<3mm descend asymptomatic Sensivity 96% Specificity 99.5% -Mean tonsillar descent 13.12+/- 7.08 mm in symptomatic group ( Barkovich et al. Am J NR ,7:795-799,1986.)

10. Chiari I definition? Analysis of 221 normal patients aged 5 months to 89 years Found a trend towards tonsillar ascent with increasing age Criteria to distinguish abnormal tonsillar ectopia - first decade - > 6 mm - 2 nd -3 rd decade - > 5 mm - 4 th -8 th decade - > 4 mm - 9 th decade - > 3 mm (Mikulis DJ. Radiology. 183:725-728, 1992)

11. Chiari I definition? Analysis of 364 symptomatic patients Tonsillar descent of at least 5mm(332 patients) Obliteration of retrocerebellar CSF spaces in all patients (65%)- syringomyelia All had varying degrees of cranial base dysplasia Significant reduction in posterior cranial fossa and total csf volume 12% - positive family history of Chiari I or syringomyelia Extent of tonsillar descend cannot be the sole criteria for diagnosis ( Milhorat TH et al. Neurosurgery.44:1005-1017,1999.)

12. Chiari I Malformation

13. Associated anomalies – Chiari l 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

14. Associated anomalies – Chiari l Spine Klippel-Feil deformity Atlantoaxial assimilation Retroflexion of odontoid process Thickening of ligamentum flavum Scoliosis

15. Associated anomalies – Chiari l Ventricle and cistern Hydrocephalus (3-10%) Elongated 4 th ventricle Retrocerebellar CSF space are obliterated or diminished

16. Associated anomalies – Chiari l 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

17. Associated anomalies – Chiari l Spinal cord Syrinx (50-75%)

18. Associated anomalies – Chiari l Brain Elongated midbrain, pons and medulla Medullary kinking or flattening Tonsils- peg like, lose folial pattern, atrophic

19. CHIARI MALFORMATION II - Caudal herniation of brainstem, cerebellar vermis, and fourth ventricles. - associated with myelomeningocele & intracranial anomalies. - hydrocephalus & syringohydromyelia common

20. Chiari II Malformation

21. Associated anomalies – Chiari ll 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

22. Chiari II Supratentorial pathology Luckenschadel or 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

23. Banana sign Normal fetus

24. Associated anomalies – Chiari ll Spine Elongated cervical spine Scalloping of odontoid processes Incomplete C1 posterior arch Klippel-Feil deformity

25. Associated anomalies – Chiari ll Ventricle and cistern Hydrocephalus (90%) Asymmetry of ventricle Colpocephaly- enlargement of atria and occipital horns Shark tooth deformity of 3 rd ventricle Elongated, flat and small 4 th ventricle Absent inferior medullary velum Foramen of Magendie absence or associated cyst

26. Associated anomalies – Chiari ll Meninges Abnormal tentorium cerebelli Elongated incisura Low lying tentorium Vertical straight sinus low lying torculla Fenestrated or hypoplastic falx cerebri Thickened arachnoid Thickened cephalad dentate ligament Arachnoid cyst

27. Associated anomalies – Chiari ll Brain Telencephalon Corpus callosal agenesis Absent septum pellucidum Polygyria Chinese lettering of occipital and parietal lobe Agenesis of olfactory tract/bulb Absent cingulate gyrus

28. Chiari II Malformation

29. Associated anomalies – Chiari ll Brain Diencephalon Interthalamic adhesions Elevated hypothalamus Elongated pineal gland Elongated habenular commissure

30. Associated anomalies – Chiari ll Brain Mesencephalon Elongated mid brain Shortened quadrigeminal plate Tectal beaking Forked , kinked shortened aqueduct Dysgenesis of cranial nerve nuclei

31. Associated anomalies – Chiari ll Brain Metancephalon Smaller cerebellum Towering of cerebellum Tonsillar and vermian herniation Dysplasia of cerebellum Banana sign- curved cerebellum Cerebellar inversion Elongated and flattened pons Dysplastic cranial nerve nuclei

32. Chiari II Malformation

33. Associated anamolies – Chiari ll Brain Myelencephalon Elongated and flattened medulla (trumpet like ) Cervicomedullary kink Cephalad pyramidal decussation

34. Genetics of Chiari Familial occurrence Concordance in twins and triplets Association with other genetic disorder Spondyloepiphyseal dysplasia tarda Hadelu-Cheney syndrome Klippel-Fiel syndrome achondroplasia

35. Genetics of Chiari Risk of inheritence No data available Incidence of familial syringomyelia – 2% Incidence of familial CM l – 12% Pattern of inheritence Autosomal dominant with reduced penetrance Autosomal recessive ( Milhort et al.Neurosurgery.44:1005-1017,1999)

36. Acquired Chiari Malformation Acquired Chiari I malformation secondary to spontaneous spinal cerebrospinal fluid leakage and chronic intracranial hypotension syndrome in seven cases. (Atkinson JL et al. J Neurosurgery. Feb;88(2):237-242,1998) The acquired Chiari malformation and syringomyelia following spinal CSF drainage (Johnston I et al. Acta Neurochir (Wien). 140(5):417,1998)

37. Chiari III : herniation of brainstem 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

38. CHIARI 3 : occipital encephalocele with chiari 2

39. Chiari IV : cerebellar hypoplasia or aplasia ( 1896). Post fossa size normal. No hindbrain herniation . Tentorium cerebelli also hypoplastic .

40. CHIARI 4 :Cerebellar hypoplasia/ aplasia

41. Syringohydromyelia

42. Syringohydromyelia A longitudinally disposed fluid filled cavity within the spinal cord Not a disease but a condition with many possible causes. Alternative Nomenclatures : Hydromyelia - dilatation of central canal lined by ependyma Syringomyelia - cavitation in the spinal cord lined by glial tissue. Syringohydromyelia - combination of the two.

43. History Estienne (1545) – first to describe cavitation of the cord Portal (1804) - observed paresis in relation to it. Ollivier d’ Angers – coined the term syringomyelia Schuppel( 1865) – hydromyelia Simon(1857) – distinguished between the two. Schultze (1882)- syringobulbia Gardner (1945 )- hydrodynamic theory Williams(1969)- craniospinal dissociation theory

44. Syringohydromyelia Classification Barnett’s (1973) Communicating: 1. associated with developmental anomalies 2. associated with acquired anomalies Non communicating: 1. Post traumatic 2. Arachnoiditis 3. Tumors 4. Idiopathic .

45. Although Barnett and colleagues introduced the term communicating syringomyelia with the assumption that in syringomyelia associated with Chiari malformation a communication between fourth ventricle and spinal cord either exists or had existed at some time and then got blocked of, no such continuity of CSF flow between fourth ventricle and syrinx could be demonstrated even with high quality magnetic resonance imaging.

46. Milhorat classification:- 1. Communicating -occuring with hydrocephalus and anatomicaly continuous with IV ventricle. 2.N on-communicating- separated from IV ventricle by a syrinx free segment of cord. 3.Atrophic –myelomalacia.

47. Syringohydromyelia Classification Batzdorf (1991): 1. Related to abnormalities of CVJ a) adult form -CIM b) infantile form- CII M / CIII M /Dandy Walker 2. Primary spinal a) post traumatic- spinal injury / postoperative b) post inflammatory- post infectious -chemical meningitis

48. Pathology Microscopically lined by thick connective tissue, ( derived from an often-thickened pia mater)/ glia or ependyma. extensive glial meshwork with relatively sparse nuclei rarefaction and hypertrophy of astrocytes (consistent with chronic edema). glial tissue shows degenerative changes. include poorly staining or pyknotic nuclei. amorphous faintly eosinophilic material of glial origin. variety of homogeneously eosinophilic bodies including Rosenthal fibers. numerous abnormal blood vessels with enlarged lumens and thickened walls.

49. Clinical features

50. Chiari I Chiari I HEAD ACHE Most common symptom (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

51. 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

52. 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

53. Chiari I Spinal cord/ syrinx

54. 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 Tongue – fasciculations/ atrophy Dysphagia Hiccups Severe snoring Respiratory dysrhythmias Facial numbness Drop attacks Dysarthria

55. Chiari I Cerebellar: Nystagmus: horizontal or rotary on lateral gaze Ataxia: appendicular Dysmetria

56. Chiari II Commonly presents in 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

57. Clinical features Chiari II

58. Chiari II Brain stem Nystagmus: first, coarse, lat gaze evoked Poor sucking/ dysphagia/ aspiration Arching of head/ fixed retrocollis/ ophistotonus “Good baby” – feeble cry Inspiratory wheeze or stridor on agitation (cf: epiglottitis) Apneic spells – cyanosis/anoxic seizures – exhausted- sleeps Vocal cord abductor palsy (b/w cyanotic attacks) Gag : blunted or absent VII nerve paresis Dysconjugate eye movements Mirror movements

59. Chiari II Spinal cord/ syrinx Spasticity of upper extremities: severe/ progressive Weakness of lower extremities: myleomeningocoele Persistent cortical thumb Suspended dissociated sensory loss (pain/ temperature) Upper extremity weakness and wasting of hand muscles Scoliosis

60. Chiari II Cerebellar: Nystagmus: horizontal or rotary Appendicular ataxia: “falls so much”, gait changes Dysmetria: inability to feed himself

61. Comparison of Chiari I & II anomalies Findings Chiari I Chiari II Caudal dislocation medulla unusual yes Caudal dislocation into cervical canal tonsil Inferior vermis, medulla, 4 th ventricle Spina bifida May be present Rarely absent Hydrocephalus May be absent Rarely absent Medullary kink absent Present in 55% Course of upper cervical nerves normal cephaled Age of presentation Young adults infancy Usual presentation Cervical pain Progressive hydrocephalus, respiratory distress

62. PATHOGENESIS OF CHIARI MALFORMATION and SYRINGOMYELIA

63. Isolated Congenital Syndromic ↑ICT conditions Acquired ↓Skull vol Pressure gradien t CHIARI 1

64. Theories Hydrocephalus theory ( Chiari , 1891) attributed the congenital hindbrain herniation to ‘ chronic hydrocephalus of the cerebrum’ with ‘ pushing out ‘ of the cerebellum and the brainstem through the foramen magnum * hydrocephalus not universal and children with hydrocephalus and no dysraphism do not have herniation * upward herniation through tentorial notch along with caudal displacement of hindbrain in Chiari II with hydrocephalus

65. Cerebral Dysgenesis theory ( Cleland,1883 ) dysplastic changes in brainstem,, cerebellum,, corpus callosum based on chick embryo studies. Caudal Traction theory ( Penfield, Coburn,Lichtenstein et al.) tethering of the cord by the myelomeningocele with ‘ pulling down’ of the posterior fossa contents *reverse herniation seen in CIIM * abnormal relation of the nerve roots to cord normal in thoracic segments * tension within the caudal segments dissipated over four segments ( Goldstein & Kepes ,1966 ) * cervicomedullary kink and other anomalies not explain

66. Theories Cerebral overgrowth theory ( Barry, Patten, Stewart - 1957 ) attributed excessive volume of cerebral cortex with downward displacement of tentorium and hindbrain in an abnormal small posterior fossa. Developmental Arrest ( Daniel , Strich - 1958) the primary dysgenesis of brainstem impairs the formation of pontine flexure resulting elongated and herniated brainstem into upper cervical canal.

67. Theories Hydrodynamic theory ( Gardner & Goodall, 1965) failure of the rhombic roof to perforate resulting in the gentle undampened ‘ waterhammer ‘ effect of the arterial pulsation of the choroid plexus dissipated through a patent obex into the central canal resulting in progressive spinal cord cavitation. Pros: * animal studies to support the same by occlusion of the fourth ventricular outlet. * compensated hydrocephalus with communicating syringomyelia in 14/15 patients of myelodysplasia in whom VP shunt resulted in neurological improvement with resolution of the syrinx . ( Hall et al.) Cons : * hydrocephalus present in some. * fourth ventricular obstruction not present in all. *obex rarely communicates with syrinx.

68. Craniospinal Pressure Dissociation theory ( William , 1969) Attributed venous pressure changes rather than arterial pulsations as the driving force for hydromyelia . Proposed that - increase in the subarachnoid fluid pressures resulted from increase in venous pressure during coughing and Valsalva ‘s maneuver due to distended epidural venous plexus resulting in the cranial flow of CSF with dissipation of pressure difference. - hindbrain herniation prevents this caudal flow of CSF due to ball valve effect of the tonsils which impact at the foramen magnum Pros: - explained the association of foramen magnum obstruction with progression of syrinx . - experimental evidence to demonstrate significant craniospinal pressure difference which normalized following decompression. Cons: -Only 10% had radiological evidence of communicating syrinx . - myelography evidence shows cord compression not dilatation during increase in spinal venous pressure.

69. - ‘ cork in a bottle ’ phenomenon results in cranio spinal pressure differences over 100 mm Hg which ‘ sucks ‘ the fluid into the syrinx cavity from the fourth ventricle through the patent obex (eventually sealed off by the impacted hindbrain) later through normal brain tissue. - venous dilatation creates a fluid wave exerting pressure on the cavitated cord thus propagating the syrinx by a ‘ sloshing action ’.

70. Theories Du Boulay modification of Gardner ‘s theory ,1974. - craniospinal pressure dissociation secondary to foramen magnum blockage but prevention of CSF egress during systole is the driving force for hydromyelia . Disproportionate CSF absorption theory (Fischer, Welch) disproportionate amount of CSF absorbed/ drained from the spinal canal induces a negative pressure gradient resulting in secondary herniation -acquired Chiari malformation eg . Following Lumboperitoneal shunt insertion. - CM usually seen in adults not in children.

71. Theories Aboulker’s theory , 1979 ‘’ obstruction at the cisterna magna associated with high venous pressure caused transmedullary passage of CSF which produces progressive cavitation “ - initiated by the stenosis of the dural sac at the level of foramen magnum,thus intracranial CSF doesn’t flow caudally and 30% of the spinal fluid unable to ascend up resulting in edema progressing to cavitation . Pros: - metrizamide scan suggests transneural migration into the cavity. - communication of syrinx with spinal subarachnoid space. Cons: -documentation of venous hypertension in spinal cord not convincing. .

72. Theories Taylor’s theory ,1975 ‘’impaired venous drainage results in central cord necrosis and secondary cavitation .’’ But neither physiological evidence of venous obstruction nor histology of syrinx suggestive of hemmorhagic necrosis

73. Theories Mesoderm “ too small posterior fossa ” theory ( Marin Padilla ,1981) - experimentally treated hamsters with excess Vitamin A - resulted in underdevelopment of occipital squamosa with small posterior fossa with consequent cephalocranial disproportion. - barrier against the growth of the neural structures with displacement upward and downward outside the confines of the fossa. - radiographic morphometric measurements in 364 symptomatic CIM concluded paraxial mesoderm disorder with underdevelopment of posterior fossa cranium/compression of normal hindbrain (Milhorat TH et al. ,1999)

74. Theories Ball and Dayan’s theory (1972) ‘’Syrinx cavity produced by CSF tracking under pressure from spinal subarachnoid space into the cord along perivascular (Virchow – Robin ) spaces.’’ Pros: - explained the separation of syrinx cavity from the central canal - communication of syrinx with spinal subarachnoid space demonstrated using metrizamide myelogram. Cons: -pressure external to syrinx would tend to collapse rather than enlarge it. Aboulker –fluid enter along dorsal nerve roots.

75. Theories Mclone and Knepper’s Unified theory (1989) -based on assumption that neural tube defect primary with secondary manifestations of Chiari and hydrocephalus. -in- utero abnormal pressure differential results in vermian herniaton without tonsillar involvement, development of vermis predates that of cerebellar hemisphere and tonsils(Osaka et al.,1978) - CSF leak through defect results in lack of distension of cranial ventricular system which is a prerequisite for normal development of cerebral cortex and overlying skull.

76. - Thus disorganization of the developing cerebral cortex with low lying tentorium and small posterior fossa due to lack of the inductive effect of fourth ventricle. -lack of third ventricle distension with apposition of thalami and massa intermedia. -lack of pontine flexure with elongation of brainstem and resultant upward & downward herniation. * links the etiology of the Neural tube defect, CIIM and associated anomalies.

77. Oldfield’s theory ( 1994) It is currently a widely accepted theory. - hypothesized that CSF in spinal cord acts from outside the spinal cord and not from within. - Brain expands in systole → Tonsils pushed to spinal canal → ↑ spinal sub arachnoid pressure → CSF forced through peri vascular and interstitial spaces to canal→ Propulsion of syrinx fluid up and down → origin and propagation of syrinx . - systolic pressure wave imparted to intracranial CSF due to blood flow to the brain is normally adjusted by sudden CSF movement from basal cisterns to upper spinal canal. - In Chiari I , piston like movement of the cerebellar tonsils down the foramen magnum results in systolic pressure wave in spinal CSF . -pressure waves act on the surface of the cord and forces CSF into the parenchyma along the perivascular and interstitial spaces.

78. -once syrinx formed ,longitudinal propulsion of fluid with propagation of cavity * detected preoperatively with Dynamic cine phase MRI and intraoperative by ultrasound showing pulsatile excursion of the cord surrounding the syrinx . - based on this bone and dural decompression of the foramen magnum alone is adequate treatment without entering the arachnoid.

79. (Nishikawa et al, 1997) suggested that the fundamental defect may involve underdevelopment of the occipital somites originating from para-axial mesoderm leading to underdevelopment of the occipital bone and overcrowding of cerebellum within a too small posterior cranial fossa causing tonsillar herniation. (Nishikawa M. J Neurosurg 86:40-47, 1997)

80. Natural history-varies from spontaneous and complete regression to progressive devastating neurological deficits. Boman and livanainen (1920-1965)-university of Helsinki. Reported 55 unoperated patients of syringomyelia . Slow progression in all cases. 3 had disability within 5 years of onset. 28 had slow progression with worsening. 27 had stationary period for 10 years. Patient having chiari malformation not mentioned.

81. Natural History Patients with normal sized cord more likely to have benign course. In case cord dilation present symptoms tend to progress.

82. Natural history So far 30 cases reported to have resolution of Chiari malformation with syringomyelia Paediatric as well as adult cases Duration 1.3 yr to 8 yr Complete to partial resolution of syrinx Complete to partial resolution of tonsilar descend Asymptomatic to static clinical status Kyoshima K et al , Neurosurgery 53:762-769, 2003

83. Natural history Pathophysiological mechanism in children their is enlargement of the posterior fossa with differential growth between the bone structures and the central nervous system leads to Chiari I malformation improvement, with restoration of normal CSF flow at the foramen magnum and consequent resolution of syringomyelia Castillo Met al,AJNR 16:1158–1160, 1995. spontaneous recanalization of CSF pathways at the foramen magnum might have occurred because of rupture of the arachnoid membranes obstructing the CSF flow Klekamp J et al,Neurosurgery 48:664–667, 2001. older people,brain atrophy, especially that of the cerebellar tonsils Mikulis DJet al,Radiology 183:725–728, 1992. rupture of the syringomyelic cavity into the spinal subarachnoid space (fissuring) Jack CR Jr et al,J Neurosurgery 74:283–286, 1991.

84. Atypical presentations

85. Cerebellar Fits 1st described by Jackson in 1871 Incidence 28% Characterised by: drop attacks loss of consciousness ophisthotonic posturing varying degrees of respiratory compromise

86. Cerebellar Fits May mimic cardiogenic syncope/ epileptic disorders Seen with lesser degree of tonsil herniation and lack of syrinx May lead to death and resp arrest Blanched discolouration and deep indentation of tonsils Improves following decompressive surgery

87. Afferent respiratory dysfunction Normal facilatatory and modulatory feedback pathways that make fine adjustments in the respiratory servo mechanisms are lost Gross responses are handled satisfactorily Routine ABG, vital capacities are deceptively normal Provocative factors (minor trauma, GA, narcotics, changes in inspired CO2 mixture) cause respiratory deterioration Sudden respiratory arrest (Arora P et al, symptomatic chiari I malformation, Neurology India, dec 2004, Vol 52 Issue 4)

88. Management of Chiari-Syrinx Complex

89. Establishment of Diagnosis X ray CVJ and cervical spine... Computed Tomography Scanning (CT) Magnetic Resonance Imaging (MRI) Cardiac gated cine MRI for CSF flow study

90. MRI Investigation of choice 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

91. Cardiac gated PC cine MRI for CSF flow Definitive role in decision making Tonsillar morphology is not equivalent to symptomatology (Meadows et al J Neurosurg 2000;92:920–26 ). Treatment options following failed FMD

92. Qualitative Vs Quantitative PCMR Presence of CS flow across the FM is not the only factor Quantitative factors involved Peak flow velocity Duration of flow during systole and diastole

93. OBSERVATION PFD PFD + DURAL SCORING OBEX PLUGGING PFD + ARACHNOID DISSECTION AND DUROPLASTY PFD + DUROPLASTY PFD AND DUROTOMY WITHOUT CLOSURE TONSILLAR RESECTION PFD WITH POST. FUSION SHRINKAGE OF TONSILLS TRANS ORAL ODONTOID RESECTION DETETHERING OF CORD PFD + ODONTOID RESECTION + PFD +/- INTRA DURAL PROCEDURES. PFD WITH SHUNTING THE SYRINX

94. Indications for surgical Intervention Progressive neurological deficit Progressive enlargement of syrinx Question of close follow-up Individualize the treatment

95. PFD vs PFDD Durham and 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

96. clinical improvement were 65% in the PFD patients and 79% in the PFDD patients Syrinx resolution :56% in the PFD patients and 87% in those undergoing PFDD. Although direct comparisons have not demonstrated a statistically significant difference in clinical outcomes, the large majority of studies reporting the clinical efficacy of PFDD for the most common presentations have demonstrated rates of improvement superior to those of PFD

97. Goal of surgery Arrest the progression Responders and non responders Realistic and expected outcomes

98. Prognostic variables in chiari Poor Signs and symptoms of syringohydromelia Atrophy Ataxia Nystagmus Good Syndrome of paroxysmal intracranial hypertension Cerebellar syndrome Brainstem syndrome Small posterior fossa Meadows et al. Neurosurgery Quarterly, Vol. 11, No. 3, 2001

99. Trends in clinical response to surgery Well responders Headache Pain Weakness without atrophy Scoliosis Poor responders Sensory Atrophy Weakness with atrophy Nystagmus Meadows et al. Neurosurgery Quarterly, Vol. 11, No. 3, 2001

100. Preoperative Prognostication Clinicoradiological Grading of syringomyelia-chiari complex Based on 5 clinical and 2 radiological features Clinical grading scores from 0 to 15 0 = asymptomatic 1-5 = mild 6-10 = moderate 11-15 = severe Radiological grading scores form 0 to 8 0 = no cyst 1-4 = mild 5-8 = severe Nair et al. SyringomyelaChiari complex: A newly proposed Grading system with clinicoradiological correlation

101. Preoperative Prognostication Clinicoradiological Grading of syringomyelia-chiari complex Observations: No significant clinicoradiological correlation pre- and postoperatively. Radiological reduction in syrinx size far outweighed clinical improvement Good correlation between chronicity of symptoms and postoperative clinical outcome: All patients had postoperative improvement in radiological grade but this could not be correlated with chronicity of disease process. Nair et al. SyringomyelaChiari complex: A newly proposed Grading system with clinicoradiological correlation

102. Evolution of treatment Historical Needle aspiration of syrinx ( Abbe & Coley) Fenestration ( Pousepp ) Gutta percha drains (Frazier) Syringosubarachnoid shunts (Love and Olafson ) Syringoperitoneal shunts Posterior fossa decompression and partial tonsillar resection (Penfield and Coburns ) Obex plugging (Gardner, Williams) FMD and drain (Bertrand) Syrinx aspiration and VA shunting ( Benini & Kraybbuhl )

103. Current treatment principles Elimination of craniospinal pressure dissociation FMD with opening of fourth ventricle and myelotomy (Rhoton) FMD with open dura and intact arachnoid (Logue) FMD with outer dural layer stripping (Isu) Syrinx-cisterna magna shunt (Milhorat) FMD with lax duroplasty (Oldfield)

104. Management Strategy Top to down rule Hydrocephalus FMD with lax duroplasty Shunting of syrinx

105. 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. Any associated pathology like hcp and BI will determine the type and modification of the procedure

106. Various procedures adopted FMD alone FMD with lax duroplasty FMD with arachnoid adhesiolysis and lax duroplasty FMD with tonsillar resection, pexy etc and lax durplasty FMD with any of the above and additional removal of C2. FMD = Suboccipital craniectomy encompassing the foramen magnum rim and C1 posterior arch excision

107. Additional procedures for associated problems Hydrocephalus VP shunt ETV ( Missimi et al - NS 2011) Ventral Bony CMJ compression Ventral decompression with or without fusion CVJ instability Posterior fusion

108. Surgical Technique Bony decompression Dural procedures Arachnoid handling Dealing with the tonsils

109. Positioning

110. Skin Incision Extent: Just below inion Just past the C2 spine

111. Muscle dissection

112. Bone Removal

113. Dural Opening

114. Dural Opening

115. Bleeding at durotomy Cerebellar dura may have venous lakes Circular or occipital sinus may bleed profusely Control Proceed slowly Bipolar Metal Clips Figure of 8 stiches

116. Intradural exploration Arachnoid opening Under magnification Midline Avoid adherant PICA Only sharp dissection

117. Handling the tonsils

118. Morphological variants of tonsils ( described by Batzdorf ) Simple tonsillar impaction(mobile tonsils) Adherent tonsillar impaction dense arachnoid scarring ( gliotic tonsils) Vascular membrane (encased tonsils) Membranous occlusion of the fourth ventricle

119. Management of Descended Tonsils Batzdorf advices the following strategy: for mobile tonsils : Bipolar coagulation of the tonsils to shrink it. for gliotic tonsils : amputation of the tonsils. for adherent tonsils : subpial resection of the tonsils (dorsally & laterally to avoid scarring in midline) for encased tonsils : midline dissection to the fourth ventricle with tubular shunt to cervical subarachnoid space. for membranous occlusion of the fourth ventricle: division of the membrane, permanent arachnoid retraction sutures to maintain seperation of tonsils in the midline.

120. Dural Closure

121. Wound closure Layered closure Muscle Facia Subcuticular Skin

122. Postoperative complications Early CSF Leak Address HCP Resuture Lumbar drain Meningitis – Infective / Chemical Non autologous graft Dura not closed Meticulous and clean procedure

123. Postoperative Complications Early Lower cranial nerve dysfunction Brainstem dysfuctions Hematoma

124. Postoperative Complications Late Symptom recurrence Occur after initial improvement Due to: New or enlarging syrinx CSF obstruction due to scarring Cerebellar ptosis Pain Instability

125. Shunting of syrinx Indication: Persistent symptoms Non resolution of syrinx PCMR shows normal flow study Options: SSS SPS TPS Terminal ventriculostomy

126. Recurrent or Unresolved Chiari 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

127. Intraoperative color doppler after FMD Adequacy of CSF flow Bidirectional flow across FM Waveform exhibiting dual variations vascular respiratory A peak velocity of 3-5 cm/sec (Milhorat, 2003, NS) Intraoperative adjuncts for adequate posterior fossa decompression

128. COMPLEX CHIARI MALFORMATIONS

129. There are subcategories of patients in whom the condition was more complex ; these patients in whom the condition is more complex these patients require more surgical intervention than others. Grabb and colleagues in 1999 showed that odontoid retroflexion , manifested by a pBC2 distance (maximum perpendicular distance to basion-inferoposterior point of the C2 body) greater than 9mm defined a patient that required craniocervical fusion procedures.