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

Cerebrovascular disease is a prevalent condition that affects a large number of people, particularly older adults. It can cause a range of serious complications, including stroke, which can lead to long-term disability and death. Early diagnosis and treatment are crucial to reduce the risk of such complications.

In this blog we’ll cover neural tube defects, meningocele, arnold chiari malformation and brain herniation syndrome. Read on.

Neural Tube Defects

Types 

SPINA BIFIDA OCCULTA	SPINA BIFIDA APERTA
Also Called as Closed spina bifida Associated with incomplete Closure of one or more vertebra without Herniation of meninges or Spinal cord	Divided in 3 types  MENINGOCLELE Myelomeningocele Myeloschisis

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

Ischemic (85%)	Hemorrhagic (15%)
Embolic (75%) Thrombotic (25%)	Parenchymal (10%)  SAH (1-2%) EDH (1%) SDH(<1%)

• 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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