16.Ventricular System of the Brain.pdf

THE UNIVERSITY OF ZAMBIA SCHOOL OF MEDICINE HUMAN ANATOMY Ventricular System of the Brain Dr. Mukape Mukape - UNZA (BSc.HB, MBChB, MSc) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 1  VENTRICULAR SYSTEM OF THE BRAIN 6/24...

THE UNIVERSITY OF ZAMBIA SCHOOL OF MEDICINE HUMAN ANATOMY Ventricular System of the Brain Dr. Mukape Mukape - UNZA (BSc.HB, MBChB, MSc) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 1  VENTRICULAR SYSTEM OF THE BRAIN 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 2  Ventricular System of the Brain Basically, the ventricular system of the brain is made up of 4 ventricles: 1. Two lateral ventricles 2. The 3rd ventricle 3. The 4th ventricle The right and left lateral ventricles are located in the cerebrum (telencephalon) The 3rd ventricle is in the diencephalon 4th ventricle is in the pons and medulla oblongata (rhombencephalon = metencephalon and myelencephalon) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 3 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 4 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 5 Communications: - Between the lateral ventricles and the 3rd ventricle via the interventricular foramina of Monro - Between the 3rd ventricle and the 4th ventricle via the aqueduct of Silvius - Between the 4th ventricle and the cisterns of the cranial subarachnoid space via three apertures: foramen of Mangendie and two foramina of Luschka - The cranial subarachnoid space is continuous with the spinal subarachnoid space which ends at approximately the 2nd sacral vertebral of the spinal cord 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 6  Cerebral Spinal Fluid (CSF) Is the “lymph” of the brain Contains a number of electrolytes and many other substances (e.g. lactate, cholesterol, uric acid) whose composition is different from that of serum One which merits mentioning is protein content In CSF, the normal value is less than 4mg/L as compared to that of serum of about 6000 mg per litre In pathological conditions e.g. meningitis, CSF protein can become abnormally elevated that it can lead to blockade of shunts used in treatment of hydrocephalus with its attendant risks 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 7  Cerebral Spinal Fluid (CSF) Normal volume ( Infant= about 50mL, Adult= about 150mL) - Mostly it is extra-ventricular in the subarachnoid space - In an adult: 25mL in ventricular system, 100mL in cranial subarachnoid space and 25mL in spinal subarachnoid space Normal pressure: about 60-150mm of H20 Formation: by ependymal cells of the choroid plexus of the ventricles, mainly the lateral ventricles: approximately= about 550-600mL per day) Circulation: is due to pressure gradient between ventricular system and the venous system) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 8  Cerebral Spinal Fluid (CSF) Absorption: - Mainly via the arachnoid villi (arachnoid granulations): are arachnoid mater protrusions which perforate dura mater to empty CSF into the dural venous sinuses Functions: - Protection of the central nervous system (CNS) - Nutrition to and removal of waste products of CNS metabolism - By Archimedes’ principle it provides buoyancy to lighten the weight of the brain (normal weight of an adult brain =1.5Kg, in skull =56g) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 9  Flow of CSF 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 10  Flow of CSF 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 11  Applied Anatomy Hydrocephalus Lumbar puncture Spinal anaesthesia 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 12  Hydrocephalus 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 13  Hydrocephalus Is the disturbance of CSF formation, flow or absorption leading to an abnormal accumulation of CSF in the ventricles of the brain Is classified according to its underlying pathology It can be classified into: 1. Communicating hydrocephalus (non-obstructive): no obstruction 2. Non-communicating (obstructive) hydrocephalus: where there is obstruction - Can also be classified into congenital or acquired hydrocephalus 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 14  Communicating hydrocephalus - No reabsorption of CSF into the dural venous sinuses - Can occur with subarachnoid haemorrhage (SAH) or congenital absence of arachnoidal granulation - This results in accumulation of CSF within the subarachnoid space causing compression of the brain tissue within the cranial cavity - This leads to brain atrophy and long-term mental retardation 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 15 CT scan See the progression 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 16  Non-communicating Hydrocephalus There is usually blockage within the ventricular system This results in accumulation of CSF within the ventricular system The brain matter therefore is pushed outwards against the skull 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 17  Causes of Non-Communicating Hydrocephalus 1. TORCHES 2. Mass lesions: abscess, haematoma, tumours 3. Aqueductal stenosis 4. Dandy Walker Malformation (DWM): - Prominent occiput due to cystic expansion of the 4th ventricle in the posterior cranial fossa and midline cerebellar hypoplasia resulting from developmental failure of the 4th ventricle during embryogenesis 5. Anold Chiari Malformation type II (ACM-II): - For-shortened occiput where portions of the cerebellum and brainstem herniate into the cervical spinal canal blocking CSF flow to posterior cranial fossa 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 18  Causes of Communicating Hydrocephalus 1. Meningitis (TB) 2. Subarachnoid haemorrhage (SAH) 3. Meningeal malignancy 4. Absence of arachnoid granulations 5. Choroid plexus papilloma 6. Basilar impression 7. Achondroplasia (due to increased dural venous sinus pressure) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 19  Questions to Establish Diagnosis Perinatal: - Was the child born at term or preterm? - Did the child cry immediately after birth? - What was the head circumference at birth? - Any abnormality of the spine? Post-natal: At what age did the caregiver notice the head getting bigger? Did the child have any fever before the head started getting big? What treatment was given and for how long? Any history of convulsions? Any similar illness in the siblings? 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 20  Clinical Presentation SYMPTOMS Children and adults include the following: - Cognitive deterioration Infants: - Headaches (initially in the morning) - Poor feeding - Neck pain, suggesting tonsillar herniation - Irritability - Vomiting, more significant in the morning - Reduced activity - Blurred vision: A consequence of papilledema and, later, of optic atrophy - Vomiting - Double vision: Related to unilateral or bilateral sixth nerve palsy - Difficulty in walking due to spasticity: more in lower limbs because the periventricular pyramidal tract is stretched by the hydrocephalus - Drowsiness 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 21  SIGNS Infants: Head enlargement (head circumference ≥98th percentile for age) Separation (dysjunction) of sutures Dilated scalp veins Delayed closure of anterior fontanelle and will be tense Positive Macewen’s sign Sun-setting eye sign: - Characteristic of increased intracranial pressure (ICP); downward deviation of ocular globes, retracted upper lids, visible white sclerae above iris - Increased limb tone (spasticity preferentially affects the lower limbs) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 22 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 23 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 24 Children and adults: Papilledema Failure of upward gaze Unsteady gait Large head Unilateral or bilateral sixth nerve palsy (secondary to increased ICP) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 25  Work UP Lab - No specific blood tests are recommended - Genetic testing and counselling when X-linked hydrocephalus is suspected - Evaluate CSF in post-hemorrhagic and post-meningitic hydrocephalus to exclude residual infection Imaging - Skull X-ray (calcifications, thin skull bones, separation of sutures, beaten copper appearance (BCA)) - CT/MRI head - EEG when seizures 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 26  Copper beaten appearance 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 27  Treatment Surgery is the mainstay of treatment Medical - Use is controversial - As temporal measure to treat post-hemorrhagic or post-meningitic hydrocephalus in neonates to delay surgical intervention - Medications: a. Decreasing CSF secretion by the choroid plexus - Acetazolamide - Furosemide b. Increasing CSF reabsorption - Isosorbide (effectiveness is questionable) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 28  Surgical Treatment Surgical treatment is the preferred therapeutic option Options: a. Shunting - Ventriculoperitoneal (VP) - Ventriculoatrial (VA) - Lumboperitoneal - Ventriculopleural - Torkildsen shunt b. Endoscopic third ventriculostomy (ETV) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 29  Shunting The principle of shunting is to establish a communication between the CSF (ventricular or lumbar) and a drainage cavity (peritoneum, right atrium, pleural cavity) Shunts are not perfect All alternatives to shunting should be considered first 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 30  VP shunt Is used most commonly The lateral ventricle is the usual proximal location The advantage of this shunt is that the need to lengthen the catheter with growth may be obviated by using a long peritoneal catheter This reduces repeated lengthening in a growing child 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 31  VA shunt Also called a "vascular shunt.“ It shunts the cerebral ventricles through the jugular vein and superior vena cava into the right cardiac atrium It is used when the patient has abdominal abnormalities: - Peritonitis - Morbid obesity - After extensive abdominal surgery This shunt requires repeated lengthening in a growing child 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 32  Lumboperitoneal Shunt Used only for: - Communicating hydrocephalus - CSF fistula - Pseudotumor cerebri 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 33  Torkildsen shunt Used rarely It shunts the ventricle to cisternal space Effective only in acquired obstructive hydrocephalus 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 34  Ventriculopleural shunt A ventriculopleural shunt is considered second line due to fear of breathing difficulties Used if other shunt types are contraindicated 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 35  Complications of Shunting 1. Risk of infection 2. Blockage of the shunt 3. Patient outgrows the shunt 4. Shunt dislodgement 5. Shunt nephritis 6. Subdural haematoma 7. Pseudocyst 8. Slit ventrical syndrome due to overdrainage (CT/MRI shows very small “slit- like” collapsed ventricles) 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 36  ETV Is a surgical procedure in which an opening (ostomy) is created in the floor of the 3rd ventricle using an endoscope placed within the ventricular system through a burr hole (trephine) This allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction It is used as an alternative to a cerebral shunt to treat certain forms of obstructive hydrocephalus, such as aqueductal stenosis Complications include subarachnoid haemorrhage, basilar artery injury and hypothalamic or pituitary injury 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 37  ETV 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 38  Lumbar Puncture 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 39  Spinal Anaesthesia 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 40  Thanks 6/24/19 Dr. Mukape: BSc. HB, MBChB, MSc, UNZA. 41