Ventricular System of Brain and its applied anatomy

D .Sreekumar.A.
Email : hmctirur@gmail.com

The central nervous system  consists of the brain and the spinal cord immersed in the cerebrospinal fluid.

Weighing about 3 pounds (1.4 kilograms) the brain lies within the cranial cavity.

The brain and the spinal cord are completely surrounded by three membranes, the Meninges,lying between the skull and the brain and between the vertebrae and the spinal cord.

Named from outside inwards they are

• Dura mater
• Arachnoid mater
• Pia mater.

(Piamater and arachnoid mater together forms the leptomeninges)

Brain is composed of

•     Cerebrum
•     Diencephalon
•     Brainstem
•     Cerebellum

Cerebrum – includes cerebral hemispheres,separated by the cerebral falx within the longitudinal cerebral fissure.Each hemisphere is divided into four lobes for descriptive purposes.

Frontal lobe,Parietal lobe,Occipital lobe,Temporal lobe.

Diencephalon – is the central core of the brain.

Brainstem is comprised of

• Midbrain – rostral part of brain
• Pons – Part between the midbrain rostrally and the medulla caudally.
• Medulla – most caudal part of brainstem that is continouos  with the spinal cord.

Cerebellum – consists of  two lateral hemispheres.

Ventricular System of Brain.

• The structures of the ventricular system are embryologically derived from the centre of the neural tube (the neural canal).
• The ventricular system of the brain consists of four irregular-shaped cavities or ventricles
• Two lateral ventricles (right and left).
• The midline third and fourth ventricles connected by the cerebral aqueduct.
• CSF,largely secreted by the choroid plexus of  ventricles,fills these brain cavities and the subarachinoid space of the brain and spinal cord.

Ventricles of the Brain

The lateral ventricles, the 1^st  and 2^nd ventricles,are the largest cavities of the ventricular system and occupy large areas of the cerebral hemispheres.Each lateral ventricle opens through an interventricular foramen into the 3^rd ventricle.

The 3^rd ventricle is a slit like cavity between the right and left halves of the diencephalons is continuous posteroinferiorly with the cerebral aqueduct,a narrow channel in the midbrain connecting the 3^rd and 4^th ventricles.

The pyramid-shaped 4^th ventricle in the posterior part of the pons and medulla extends inferoposteriorly..Inferiorly,it tapers to a narrow channel that continues into the cervical region of the spinal cord as the central canal.

Cerebrospinal fluid

CSF pressure remains almost constant at about 10cm H₂0 when the individual is lying on his side and about 30cm H₂0 when sitting up.If the brain is enlarged by,eg:haemorhage or tumour,some compensation is made by a reduction in the amount of CSF.When the volume of brain tissue is reduced,such as degeneration or atrophy,the volume of CSF is increased.

CSF is a clear,slightly alkaline fluid with a specific gravity of 1.005,consisting of

• water
•  mineral salts
• glucose
• plasma proteins
• creatnine
• urea
• few leucocytes.

Secretion of Cerebrospinal fluid
Is secreted continuously at the rate of 400-500ml/day,by the choroid epithelial cells of the choroid plexus in the lateral,third and fourth ventricles.The amount around the brain and spinal cord remains fairly constant at about 120 ml,which means that absorption keeps pace with secretion.

Choroid plexus

• consists of vascular fringes of piameter covered by cuboid epithelium.
• are invaginated into the roof of third and fourth ventricles and on the
•  floors of the bodies and inferior horns of lateral ventricles.

Circulation of Cerebrospinal fluid
CSF leaves the lateral ventricles through the interventricular foramen or foramina of Monro and enters third ventricle.From here,CSF passes through the cerebral aqueduct into the fourth ventricle.From there it can pass into the central canal of the spinal cord or into the cisterns of the subarachnoid space via three small foramina: the central foramen of Magendie and the two lateral foramina of Luschka.CSF also passes into the extensions of the subarachnoid space around the cranial nerves,the most important of which are those surrounding optic nerve. The fluid then flows around the superior sagittal sinus to be reabsorbed via the arachnoid villi into the venous system. CSF within the spinal cord can flow all the way down to the lumbar cistern at the end of the cord around the cauda equina where lumbar punctures are performed.

Absorption of Cerebrospinal fluid

Is at the same rate as of production.

The main site of absorption into the venous system is through the arachnoid granulations.

CSF enters the venous system through two routes

-Through the cells of the arachnoid granulations into the dural venous sinuses.

-Some CSF moves between the cells.

Functions of Cerebrospinal fluid

• Supports and protects, brain and spinal chord by providing a cushion and shock absorber between  brain and cranial bones.
• Provides buoyancy – CSF in the subarachnoid space provides buoyancy that prevents the weight of the brain from compressing the cranial nerve roots and blood vessels against the internal surface of cranium.
• Maintains a uniform pressure around the delicate structures.
• Keeps the brain and spinal cord moist and there may be interchange of substances between CSF and nerve cells,such as nutrients and waste products.

Subarachnoid Cisterns – At certain areas on the base of  the brain the arachnoid and pia are widely separated by subarachnoid cisterns which contain CSF and soft tissue structures that anchor the brain.

          Eg: Cerebellomedullary cistern

                 Pontocerebellar cistern.

APPLIED ANATOMY

• Monro – Kellie Doctrine
• States that the cranial cavity is a closed rigid box and that a change in the quantity of intracranial blood can occur only through the displacement or replacement of CSF.
• Methods of obtaining CSF
• To obtain CSF for examination it is necessary to puncture either the cerebral ventricles or the subarachnoid space,either in the cisterna magna or in the lumbar theca beyond the termination of the spinal cord.

Lumbar Puncture
Is the simplest method.The spinal cord terminates at the lower border of the first lumbar vertebra in the adult and at a slightly lower level in the child.The arachnoid continues downwards below the termination of the spinal cord as far as the second sacral vertebra and forms a lumbar cul-de-sac of the subarachnoid space nomally containing CSF.A needle can be introduced into this space without injuring the cord.

Method
LP or spinal tap is done to extract samples of CSF from lumbar cistern.Lumbar spinal puncture is performed with the patient leaning forward or lying on the side with the back flexed.Under aseptic conditions ,the skin coverig the lower lumbar vertebra is anaesthetized and a lumbar puncture needle fitted with a stylet is inserted in the midline between the L3 and L4 or L4 and L5 spinous processes.At these levels there is no danger of damaging the spinal cord.After passing 4-6 cms in adults the needle punctures the duramater and arachnoid mater and enters the lumbar cistern.When stylet is removed,CSF escapes at the rate of one drop per second.If subarachnoid pressure is high,CSF flows out or escapes as a jet.Lumbar puncture is not done in cases with increased ICT.

Indications

• 1)    Obtain CSF for cytological,chemical and other investigations and to estimate its pressure.
• 2)   Introduce into the subarachnoid space therapeutic substances or local anaesthetics.
• 3)   Introduce air into the sub arachnoid space for encephalography or myelography.
• 4)   Introduce opaque media for myelography.
• 5)   In benign intracranial hypertension,lumbar puncture is safe and may even be beneficial as it temporarily reduces the pressure.

Contraindications

• 1)    Raised intracranial pressure especially due to a tumour in the posterior fossa of the skull,sudden withdrawal of fluid from the spinal canal may cause herniation of the medulla and cerebellar tonsils into the foramen magnum-the cerebellar pressure cone – with fatal results.
• 2)   When ICSOL is present or suspected in one cerebral hemisphere,herniation of the medial part of the temporal lobe through the tentorial hiatus  results in compression and distortion of the upper brainstem which is disastrous.
• 3)   Skin sepsis or extradural suppuration in the lumbar region owing to the risk of infecting spinal canal.
• 4)   Marked spinal deformity in dorsal or lumbar region may render it difficult or impossible.

Dry tap
Is the failure to obtain CSF due to faulty procedure.The point of needle may not have entered the subarachnoid space.A genuine dry tap may occur when the spinal subarachnooid space is blocked at a higher level or when the lumbar sac itself is filled by a neoplasm or lipoma.

Sequelae
A throbbing headache which comes on after a few hours is the commonest sequelae.May be associated with nausea,vomiting,giddiness and pain in the neck and back.Headache which lasts for few days to weeks is due to leakage of CSF through the punctured wound.

Occasionally LP intensifies the already existing symptoms especially when a lesion is compressing the spinal cord as symptoms may be exacerabated by alterations of pressure induced by the withdrawal of fluid.

Prolapsed intervertebral disc following puncture of the annulus fibrosis.

Ventricular puncture – Puncture via a burr hole or via the lateral angle of the anterior fontanelle is now rarely used.

Cisternal puncture – Is done by penetrating the cisterna magna (cerebellomedullary cistern) which is a dilatation of the subarachnoid space.

Indications

• 1)    when lumbar puncture is not possible,eg – lumbar sepsis,deformity of spine.
• 2)   To compare the composition of or pressure of cisternal and lumbar fluids
• 3)   To inject opaque media,therapeutic substance,air for encephalography

Contraindications

• 1)    tumour or abscess in posterior fossa
• 2)   Raised ICP
• 3)   Inflammatory adhesions in cistern

Method

• Lumbar puncture needle is inserted at a point 1 cm above the spinous process of the cervical vertebra.
• Lateral Ventricuar puncture
• Technique introduced in the recent years and is used especially as a method of myelography in cervical spinal lesions.Here needle is inserted 1 cm caudal and 1 cm posterior to the tip of mastoid process.

Measurement of CSF pressure

Method of determination

The CSF pressure can be measured with a simple manometer.A graduated glass tube is attached to the lumbar puncture needle and the height in mm to which the fluid ascends in the tube is measured.The normal CSF pressure in adults is 60 to 150 mm of fluid and 45 to 90 mm in children.

Pathological variations of pressure

                   Abnormally high pressure is found in

ICSOL,haemorrhage,hypertensive encephalopathy,hypervitainosisA,hydrocephalus, intracranial sinus thrombosis,meningism,some forms of meningitis,encephalitis,uremia,corpulmonale.

                   Subnormal pressure is seen in :  Head injury,dehydration,spinal subarachnoid block,

                   Abnormally Low :  Second LP is performed shortly after previous one.

Queckenstedt’s test
Normally if one compresses the jugular veins during lumbar puncture,there is an immediate and rapid rise in CSF pressure and rapidly falls to normal when compression ceases.Venous compression causes raised pressure in the intracranial venous sinuses and hence in the cranium.This test is used to check the patency of the subarachnoid space between the cranial cavity and the lumbar sac.

CSF Examination.
CSF may be obtained by lumbar,cisternal or lateral cervical puncture or through ventricular cannulas or shunts.A manometer is attached before any fluid is removed to record the opening pressure.A dramatic pressure droop of 1 to 2 ml suggests herniation or spinal block above the puncture site. No further fluid should be withdrawn in this situation.

Upto 20ml of spinal fluid may be removed normally.

Indications for lumbar puncture can be divided into four major disease catogories.ie

• 1)    meningeal infection
• 2)   subarachnoid hemorrhage
• 3)   CNS malignancy
• 4)   Demyelinating diseases

Identification of infectious meningitis,esp bacterial is the most important indication of CSF examination.The potential yield of CSF examination in diseases should be weighed against the small risk of potentially serious complications of LP.

• Diseases detected by CSF Examination
• High sensitivity,high specificity
• Bacterial,tuberculous,fungal meningitis
• High sensitivity and moderate specificity
• Viral meningitis,Subarachnoid hemorrhage,Multiple sclerosis,CNS syphilis,Infectious polyneuritis,Paraspinal abscess
• Moderate sensitivity,high specifity

                    Meningeal malignancy

Moderate sensitivity moderate specificity- Intracranial,Viral encephalitis,Sub dural haematoma.

(Sensitivity = Ability of a test to detect disease when it is present,

Specificity = Ability of a test to exclude disease when it is not present)

GROSS EXAMINATION

• Normal CSF is clear and colorless,with a viscosity similar to water.
• Cloudiness or turbidity is seen in leucocytosis,presence of microorganisms,aspirated epidural fat,protein
• Clot formation in traumatic taps,spinal block,suppurative and tuberculous meningitis
• Viscous CSF is seen in metastatic mucin producing adenocacinomas,cryptococcal meningitis,needle injury to the annulus fibrosis.
• Pink red CSF indicates presence of blood.
• Xanthochromic CSF is pink,orange,or yellow due to RBC lysis and hemoglobin breakdown.

MICROSCOPIC EXAMINATION

Total Cell Count:
Normal leucocyte count 0 to 5 cells/micro litre in adults and 0 to 30 cells in neonates.Red Cells have limited diagnostic value but may allow a useful approximation of the true CSF WBC count or total protein in the presence of traumatic puncture by correcting for WBCs or protein introduced by bleed.

Differential count

                    Lymphocytes normal range – 62 to 92

                    Lymphocytosis is seen in

Meningitis ie viral,tuberculous,fungal,bacterial

Degenerative diseases like subacute Sclerosing panencephalitis,Multiple sclerosis,GB syndrome

Neutrophils normal range – 2 to 7

                   Increased neutrophils are seen in

Meningitis ie Bacterial,Early tuberculous,Early Mycotic,Early viral meningoencephalitis.

Infections like Cerebral abscess,Subdural empyema,

Following seizures,CNS hemorrhage,CNS infarct

Metastatic tumours in contact with CSF.

Plasma cells are not normally found in CSF

                   Plasmacytosis in CSF is seen in

Tuberculous meningitis,MS,SSP,GB syndrome,A/c viral infections

                   Eosinophils may be rarely seen in normal CSF

                   Eosinophilia in CSF is commonly associated with

Parasitic and fungal infections,A/c polyneuritis,Idiopathic hypereosinophilic syndrome.

CHEMICAL EXAMINATION

          Protein

Normal protein range is 15 to 45 mg/dl.

          Increased CSF protein is seen in

                   Traumatic spinal tap

                   Increased blood- CSF permeability

Arachnoiditis,Meningitis,Hemorrhage,Drug toxicity

                   Increased IgG synthesis

Electrophoresis

Oligoclonal bands are seen in MS,SSPE,viral CNS infections.

CRP

Increased levels of this acute phase reactant is used to differentiate bacterial from viral meningitis.

Glucose

          Normal CSF glucose levels is 50 to 80 mg/dl.

          Decreased levels are characteristic of

                   Meningitis – bacterial,tuberculous,fungal

                   Hypoglycemia

          Increased CSF glucose is of no clinical significance

                   May be seen in traumatic tap.

Lactate

          Normal range is 9.0 to 26.0 mg/dl

Elevated levels eflect anaerobic metabolism within CNS due to tissue hypoxia.

Used to differentiate viral from bacterial,mycoplasmal,fungal,and tuberculous meningitis.

Persistent elevation of Ventricular CSF lactate levels are associated with a poor prognosis in patients with severe head injury.

Enzymes

CSF Glutamic-oxaloacetic transaminase activity is raised in some cases of cerebral infarction and MS

                   CSF creatnine kinase activity is raised in muscular dystrophy

Sterols

                   CSF cholesterol is raised in MS

Keratin

Presence of keratin in CSF may indicate the presence of an intracranial epidermoid cyst.

Microbial examination

To differentiate Bacterial,Viral,Fungal and tuberculous meningitis

Also useful in Neurosyphilis,HIV,Primary

Ameobic Meningoencephalitis(PAM)

Spinal block

An anaesthetic agent can be injected into the CSF.Anaesthesia usually occurs within 1 minute.A headache may follow a spinal block,which likely results from the leakage of CSF through lumbar puncture.

Epidural blocks

An anaesthetic can be injected into the extradural space.

          Eg:- lumbar epidural block,caudal epidural block.

Regional anaesthesia for childbirth can be done by spinal or caudal epidural block.

Diseases of the ventricular system include

-abnormal enlargement (hydrocephalus)

-inflammation of the CSF spaces (meningitis)

caused by infection or introduction of blood following trauma or hemorrhage.

Hydrocephalus

• Overproduction of CSF.
• Obstruction to flow of CSF.
• Interference with absorption of CSF.
• Excess fluid in Cerebral ventricles.
• Brain is squeezed between ventricular fluid and calvarial bone.
• In infants raised internal pressure results in expansion of brain and calvaria because sutures and fontanelles are open.

Obstruction to flow of CSF can occur at any place,the blockage usually occurs in cerebral aqueduct or at interventricular foramen.Aqueductal stenosis may be caused by a nearby tumour or cellular debris following infection or haemorrhage.It is possible to bypass the blockage and allow CSF to escape there by lessening the damage.

In Communicating Hydrocephalus,flow of CSF is not impaired.But movement of CSF into venous system is partly or completely blocked.Blockage may be caused by the congenital absence of arachnoid granulations or the granulation may be blocked by RBC after haemorrhage.

Hydrocephalus ex-vacuo occurs when there is damage to the brain caused by stroke or injury, in which there may be actual shrinkage of brain tissue.Hydrocephalus ex-vacuo is essentially only hydrocephalus by default,the csf pressure itself is normal.In old age or persons with Alzheimer’ disease,the entire brain itself may shrink and the CSF itself may occupy the space created by shrinkage.

Acquired hydrocephalus  As a result of something blocking the drainage of CSF after birth.Culprits can include a brain tumour,arachinoid cyst,inflammation of brain,haemorrhage or trauma.Bacterial meningitis is also an imp cause.

Congenital hydrocephalus  due to birth defect or brain malformation.Causes include viral infection,inheritance as an X-linked genetic trait.

Normal pressure hydrocephalus (NPH) – Due to gradual blockage of CSF drainage pathways in brain.Although ventricles enlarge the intracranial pressure remains within normal range.Occurs as a complication of infection or bleeding.Clinically presents as memory loss,gait disorder,urinary incontinence and a general slowing of activity

Treatment

Ventriculoatrial or ventriculoperitoneal shunting may be necessary wen hydrocephalus is progressive or causes symptoms.Neurosurgical removal of tumours should be carried out in appropriate cases.

Therapeutics

Hedra helix  Chronic hydrocephalus,Rhinorrhoea,cerebro-spinalis.Cataract.Acts on blood vessels,menorrhagia.

Helleborus A remedy in low states of vitality and serious disease. Characteristic aggravation from 4 to 8 p.m.SINKING SENSATION. State of effusion in hydrocephalus. Mania of a melancholy type.Hydrocephalus; in stage of effusion; with signs of depression; stupor and unconsciousness pupils sluggish; forehead corrugated, automatic action of one arm or one leg; the face flushes and pale; drinks greedily from nervousness; child suddenly screams out and bores its head into the pillow; the head is hot and the eyeballs are distorted;motion of jaws as if chewing.

Laburnum or Cystisus Laburnum – Hydrocephalus. Constant vertigo; intense sleepiness.

Zincum Met – Hydrocephalus. Rolls head from side to side. Bores head into pillow.

Argentum nitricum – Hydrocephalus-where the child begins to roll its head, throw it back and cry out in sleep or awake

Calcarea carbonica – Calcarea carbonica finds its place in the early stage of acute hydrocephalus when Belladonna does not act; the abdomen is distended, the limbs wasted; there is sweating of the head during sleep; weak memory.

Apis mellifica – Its favorable action is shown by an increase of urine. The child is very drowsy and the accumulation of fluid in the brain is very rapid.Child bores its head backwards into the pillow, rolls it from side to side, rouses from sleep with a shrill, piercing cry; on side of the body may be convulsed or paralyzed; thee is strabismus and the urine is scanty.

Apocynum – Acute hydrocephalus.Bradycardia is a prime indication. The dropsy is characterized by great thirst and gastric irritability. It is suitable to more advanced cases where the head is large, the fontanelles are wide open; it lacks the cephalic cry of Apis.

Silicea – Head large sweat on whole head rather than on scalp alone, sudden startings in sleep, sour eructations, and redness of face, cold hands and feet will well indicate.

Digitalis – When the urine is scanty and aluminous, and when the pulse is also; perhaps cold sweat on surface of body.

Sulphur – When Apis fails and when general Sulphur symptoms are present; the child is in a stupor; cold wet; jerking of the limbs, suppressed urine; child wants to lie with its head low; cries out in sleep as if frightened; face red and pupils dilated.

• [Complete ] [Head]Hydrocephalus:
• [Complete ] [Vision]Loss of vision, blindness:Hydrocephalus, in:
• [Complete ] [Face]Coldness:Hydrocephalus, in:
• [Complete ] [Rectum]Diarrhea:Hydrocephalus, during acute:
• [Complete ] [Generalities]Convulsions:Hydrocephalus, with:
• [Kent ] [Head]Hydrocephalus:
• [Kent ] [Face]Coldness:Hydrocephalus,in:
• [Kent ] [Rectum]Diarrhoea:Hydrocephalus acutus,during:
• [Kent ] [Urine]Milky:Hydrocephalus in,little but frequent milky urine with unconsciousness and delirium:
• [Boenning ] [Sensation and complaints in general]Infants:Head, hypertrophy, hydrocephalus, etc.:
• [Boger ] [Supplimentary references]Hydrocephalus:
• [Knerr ] [Inner Head]Brain:Hydrocephalus:
• [Knerr ] [Outer Head]Large:Hydrocephalic:
• [Knerr ] [Inner Head]Brain:Hydrocephaloid:

MENINGITIS

Etiology

May be caused by bacteria,viruses,fungi,other organisms,malignant cells,drugs and contrast media,blood(following SAH).Microorganisms reach the meninges either by direct extension from the ears,nasopharynx,a cranial injury,or by spread via the blood stream.Immunocomprimised patients are at an increased risk.

C/f : Meningitic syndrome means the triad of headache,neck stiffnes and fever.Photophobia and vomiting are often present.

Specific varieties of meningitis

                    Acute bacterial meningitis

                             Sudden onset with rigors and high fever.

                             Petechial rash

Viral meningitis

                             Benign,self limiting,lasting for 4-10 days

                             Headache may follow for some weeks

                    Chronic meningitis

                             Gradual onset of signs

                             Drowsiness,focal signs and seizures are common

                             Eg:- Tuberculosis,Syphilis,Sarcoidosis

                    Malignant meningitis

                             Due to malignant cells

                   Subacute or chronic noninfective

                             CSF cell count is raised with high protein and low glucose.

D/d

                    SAH,migraine,Cerebral malaria.

Therapeutics

Aconite-When caused be exposure to the sun.

Apis-fidgetiness, there are shrill outcries in sleep. the eruption is either suppressed or undeveloped; stage of effusion. Squinting, grinding of teeth, violent fever.

Belladonna-The symptoms are severe and violent. There is intense congestion, throbbing, grinding of teeth and crying out in sleep; it picture acute meningitis before exudation. Sharp pains, red face and acuteness of symptoms are marked.

Bryonia – In the stage of effusion. Face flushes and pales alternately; child screams if move the least. Has a hastiness in manner. White tongue and is thirsty.

Cuprum- When it arises from a suppressed eruption. There is violent delirium, blue face, convulsions, with clenched hands, rolling of eyeballs, grinding of teeth, followed by deep sleep.

Hellebores – Stage of exudation. Shooting pains in head; bores head into pillow; automatic motion of an arm and foot;eyeballs turned upwards; is hasty in manner.

Zincum-Sharp pains through head; especially in meningitis arising from non-development of an eruption; constant fidgety motions of feet. Little or no fever and hyperaesthes of all the senses and skin.

Tubercular Meningitis

Artemisia vulgaris, Baryta carb. and Calcarea carb.

• [Kent ] [Back]Inflammation:Membranes,spinal meningitis:
• [Kent ] [Extremities]Paralysis:Upper limbs:Meningitis,during:
• [Complete ] [Generalities]Convulsions:Meningitis, in cerebro-spinal:
• [Complete ] [Back]Inflammation:Membranes, spinal meningitis:
• [Complete ] [Head]Inflammation, of:Meninges, meningitis:
• [Complete ] [Mind]Unconsciousness, coma:Meningitis, in:
• [Complete ] [Mind]Stupor:Meningitis, in:
• [Complete ] [Mind]Shrieking, screaming, shouting:Meningitis, in:
• [Complete ] [Mind]Delirium:Meningitis cerebrospinalis, encephalitis, in:

Subarachnoid haemorrhage.(SAH)

Is the extravasation of blood into the subarachoid space particularly of the basal cisterns and into the cerebrospinal fluid pathways.

C/f     Worst of all headaches

Abrupt onset of headache associated with photophobia and stiff neck

        Focal neurological defecits such as hemiparesis or dilated pupil

        Vomitting

Typically occurs at 50 to 60 yrs of age with a high mortality rate of 35%.

Warning leak – minor leaks hours or days prior to the major haemorrhage often misdiagnosed as simple headaches or migraine.

          Etiology

Commonly caused by ruptured aneurysm,atreriovenous malformation,hypertension or trauma to the circle of Willis (often at MCA).Trauma is the most common cause.Rarely tumors and blood dyscrasias also become the cause.

D/d :    Intracerbral haematoma,Meningitis,benign cephalagia.

Investigation
Imaging – CT Scan is used to establish the diagnosis in 95% cases.This scan demonstrates blood in the cisterns and may help to localize the source of haemorrage.It can used for ruling out mass effect so that LP can be done safely.Blood appears white in non contrast CT.

An immediate LP is done if CT is negative to look for RBCs,Xanthochromasia and elevated ICP.

Angiography is performed to localize the source of bleeding once SAH is confirmed.

Complication

• Cerebral ischemia
• Acute hydrocephalus
• Rebleeding
• Paralysis

[Complete ] [Head]Cerebral hemorrhage:Subarachnoid:

Leakage of CSF

Fistulous communications may develop between the subarachnoid space and paranasal sinuses or middle ear following head injury,raised ICP due to pituiutary tumour resulting in CSF leakage.

CSF ottorrhea – Fractures in the floor of the middle cranial fossae may result in CSF leakage from external acoustic meatus.

CSF rhinorrhoea – Fractures in the floor of the anterior cranial fossae may involve the cribriform plate of ethmoid resulting in CSF leakage through nose.

CSF can be distinguished from mucus by testing its Glucose levels.But Protein electrophoresis with immunofixation for transferring is a non invasive and highly specific test.CSF will show two isoform bands while other body fluids and secretions lack the second form.

Recent research indicates that there may be a pathogenic relationship between the degenerative changes of the cerebral cortex and those of the choroid plexus.  Moreover, some research indicates that degenerative fibrillary changes in the plexus are one of the earliest manifestations of Alzheimer’s disease.Furthermore, in alzheimers disease, molecular modifications suggest that the transport and secretion of major molecules are altered in the brain.  This may consequently be the result of alterations of the basement membrane of epithelial cells in the choroid plexus.Cells of the choroid plexus can also become cancerous.  Although tumours of the choroid plexus are rare and constitute less than 1% of all brain tumours, it is one of the most frequent brain tumours in infants (up to 15%).

Interestingly, scientific study of CAT scans of the ventricles in the late 1970s revolutionized the study of mental illness. Researchers found that patients with schizophrenia had enlarged ventricles compared to healthy subjects. This became the first “evidence” that mental illness was biological in origin and led to a reinvigoration of the study of such conditions via modern scientific techniques