Cerebrovascular Disease (Meningocele, Arnold Chiari Malformation, Brain Herniation Syndrome)

Neural Tube Defects

Types 

Meningocele

• Herniation of meninges through a defect in Posterior vertebral arches 
• Spinal Cord is : Normal , Normal Position in Spinal Canal 

• C/F: 
  • Fluctuant midline swelling. 
  • Brilliantly trans-illuminant. 
  • Occurs along vertebral Column in the lower back. 
  • Covered by Skin. 
• Dx: 
  • X-ray-Vertebral Defect can be seen 
• Rx: 
  • Immediate Surgery 
    • Leaking CSF
    • Thin Skin covering
  • Delayed Surgery 

Asymptomatic with normal Neurological finding & full thickness skin covering. 

• MYELOMENINGOCELE
  • Most severe form of Dysraphism involving vertebral column 
  • Characterized by Herniation of both Meninges & Spinal Cord 
  • Incidence of myelomeningocele: 1:4000 Live Birth
  • Most common Site: LUMBOSACRAL Region

• Etiology
  • Genetic predisposition. 
  • If one child is affected, risk of occurrence – 3 to 4%. 
  • If two children are affected, risk of occurrence – 3 to 10%. 
  • Maternal Periconceptional use of folic acid supplementation decreases incidence of NTD in Pregnancies at high Risk by 50% 
• Drugs that increases risk of Neural tube defects 
  • Phenytoin
  • Carbamazepine
  • TMP-SMT (Trimethoprim-Sulfamethoxazole) 
  • Phenobarbital
  • Primidone
  • Valproate
• C/F
  • Dysfunction of skeleton, GIT, Genitourinary tract in addition to CNS & PNS 
  • Extent of Neurological Deficit depend on 
    • Site of M/M
    • Associated Lesions 
• Prevention 
  • 0.4mg Folic Acid Supplementation/Day – in all females of childbearing age & about to become pregnant 

ARNOLD CHIARI MALFORMATION

1. TYPE I CHIARI MALFORMATION
2. TYPE II CHIARI MALFORMATION

TYPE I CHIARI MALFORMATION

• Displacement of cerebellar Tonsil into cervical canal. 
• Associated with Syringomyelia of Cervical Canal. 
• Not associated with HYDROCEPHALUS
• Adolescence/Adult Life
• C/F 
  • Recurrent Headache. 
  • Neck Pain
  • Urinary Frequency
  • Progressive Lower Extremity Spasticity 

TYPE II CHIARI MALFORMATION

• It is An Anomaly of HINDBRAIN
  • Elongation of 4^th Ventricle
  • Kinking of Brain stem
  • Displacement of (Inferior vermis; Pons; Medulla) into cervical canal. 
• Associated with HYDROCEPHALUS & MYELOMENINGOCELE

Investigation 

• X-ray-Small Posterior Fossa with WIDENED Cervical Canal. 
• MRI-Cerebellar Tonsil Protruding into Cervical Canal & Hind Brain Anomalies. 
• Rx
  • Surgical Decompression 

DANDY-WALKER MALFORMATION

• Mc Posterior Fossa Malformation 
• Characterized by Developmental Failure of roof of Fourth ventricle 
• Consists of 
  • Cystic Expansion of Fourth Ventricle in Posterior Fossa 
  • Midline Cerebellar hypoplasia

• Characteristic Triad of DWH
  • Hypoplasia of Vermis
  • Cephalad Rotation of Vermian remnant and Cystic Dilation of Fourth Ventricle – Extending posteriorly 
  • Enlarged Post Fossa with Torcular Lambdoid inversion 
• C/F
  • A/W Hydrocephalus
  • MC manifestation – MACROCEPHALY
  • RAPID increase in head Size with Prominent occiput
  • Evidence of long tract signs, Cerebellar ataxia
  • Delayed Motor or cognitive milestone due to associated structural Abnormalities 
• Associations 
  • A/W CNS Abnormalities – 70% cases 
    • Agenesis of Posterior cerebellar vermis & Corpus collosum 
    • Cortical dysplasia
    • Polymicrogyria

• IOC for Diagnosis – MRI
• Rx 
  • Shunting of Cystic cavity in pts. Of Hydrocephalus 

CAUSES OF CEREBROVASCULAR ACCIDENTS

• Intracerebral Hemorrhage (Parenchymal)
  • MC Type of Intracranial hemorrhage 
  • MC cause of HTN – Rupture of small Perforating arteries & arterioles 
  • MC site – Basal ganglia (Putamen) 
  • MC site – Basal ganglia (Putamen)
• Subarachnoid Hemorrhage 
  • 2^nd MC causes of I/C Hemorrhage 
  • MC Cause is Trauma > Rupture of Berry Aneurysm 
  • MC site of Berry Aneurysm is – Anterior circulation of Circle of Willis
  • MC Site of Extra Cranial Aneurysm – Infrarenal abdominal Aorta 

BERRY ANEURYSM  

• MC type of I/C Aneurysm 
• Saccular in appearance 
• Arise from Bifurcation of I/C arteries 
• 85% Anerysm occur in Anterior circulation of Circle of Willis 
• Occurrence of Berry Aneurysm 
  • Anterior Communicating artery & Anterior Cerebral artery junction (M/C) 
  • Middle cerebral artery Bifurcation (2% MC) 
  • Posterior communicating artery & Internal carotid artery junction (3^rd M/C) 
  • Intracranial carotid bifurcation 
  • Vertebrobasilar or Basilar artery Bifurcation 
• Risk Factors 
  • Smoking 
  • Aneurysm 
  • Structural abnormality in berry aneurysm is absence of smooth muscle & intimal elastic lamina
• Wall of berry Aneurysm 
  • Made of thickened, hyalinized INTIMA. 
• Conditions Associated with berry aneurysms 
  • FMD (Fibromuscular dysplasia) 
  • Marfans syndrome 
  • Ehlers – Danlos syndrome 
  • Coarctation of aorta 
  • ADPKD (Autosomal dominant Polycystic Kidney disease)
  • NF-1
• Ruptured Berry Aneurysm 
  • Leads to intra cerebral haemorrhage or SAH or both 
  • MC Site of Rupture is Dome/Apex
• Unruptured Berry Aneurysm 
  • Completely Asymptomatic 
• Management: 
  • Endovascular coil occlusion > surgical clipping
    ↓Not possible
    Craniotomy and surgical drainage

BRAIN ABSCESS

• Occurs as a result of 
  • Direct Spread from Air sinus infection during surgery 
  • Hematogenous Spread – Associated with respiratory infection, endocarditis, Dental infection 

• ↑sed Risk of Brain Abscess 
  • Cyanotic Heart Disease 
  • Immunocompromised 
• MC site of Brain Abscess based on Etiology 
• MC site is Temporal lobe followed by Cerebellum
  • Otitis media 
  • Mastoiditis
• MC site is Frontal lobe
  • Paranasal sinusitis 
  • Dental infections
• MC site is Parietal lobe
  • Hematogenous spread
• C/F
  • FND (Focal Neurologic Deficits)
  • Seizures
  • S/S of ICT
  • Fever
• Diagnosis
  • MRI is the IOC
  • CT-Shows RING Enhancing Lesions 
• Management 
  • Surgical Drainage + IV Antibiotics – 6 Weeks 
  • Multiple small Abscess(+)- IV Antibiotics. 
  • Steroids – Reversed for pts. With Edema, Mass effect 
  • Anti-Epileptics-Increase risk of Seizure 

BRAIN HERNIATION SYNDROME

• Brain herniation SYNDROME
  • ↑ICT
    • BT
    • HEADINJURY
    • STROKE
• Boundaries 
  • Falxcerebri, Tentorium cereberum 

UNCAL/TRANSTENTORIAL HERNIATION 

• Uncus & Temporal lobes are forced through Cerebellar Tentorium 
• Sequential compression of I/L 3^rd nerve followed by Brainstem followed by whole Brainstem 
• Early Signs – I/L Dilated Pupil 
• Late Signs 
  • I/L Hemiplegia 
  • Progressive Ptosis
  • 3^rd Nerve Palsy
  • Cheyne Stoke Respiration 
• Very Late Sign 
  • Quadriparesis
  • B/L Dilated & fixed Pupil 
  • Erratic Respiration 

KERNOHAN’S NOTCH PHENOMENON

• It is Cerebral Peduncle indentation associated with Trans tentorial or Uncal herniation 
• Compression of contralateral cerebral peduncle against the free edge of Tentorium 

(KERNOHAN’S Notch) ⮕ I/L Hemiparesis & I/L 3^rd Nerve Palsy

KERNOHAN WOLTMAN SIGN

Lateral Displacement of MIDBRAIN

↓

Compress opposite cerebral peduncle 

↓

Babinski sign, Hemiparesis C/L to original Hemiparesis

CENTRAL HERNIATION

• Diencephalon (THALAMUS & Related Structures) 

↓

Forced through Tentorium. 

• Sequential Compression of upper midBrain > Pons > Medulla 
• Physical Signs of central herniation 
  • Early Sign 
  • Erratic Respiration 
  • Small Reactive Pupil 
  • Increased Tone of limbs
  • B/L Extensor Plantar
• Late Sign
  • Cheyne-stokes Respiration 
  • Decorticate Rigidity
• Very late sign 
  • Fixed & Dilated Pupils 
  • Decerebrate Rigidity 

SUBFALCINE HERNIATION 

• Displacement of Cingulate gyrus beneath free edge of falxcerebri
• Signs 
  • Loss of Consciousness – Leads to Coma
  • C/L weakness
  • Loss of Brainstem Reflexes 

TONSILLAR/DOWNWARD CEREBELLAR HERNIATION 

• Displacement of cerebellar tonsils Via Foramen magnum 
• Leads to coma & B/L Posturing 

DURET HEMORRHAGE

↑ Intracranial Tension (ICT)→ Cause Downward herniation of Brainstem 
↓
Stretching of perforators of Basilar artery. 
↓
Leads to Bleeding 

• Small area of bleed in Ventral & Paramedian Part of upper Brainstem (Midbrain & PONS) 

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