Cell Cycle

3 phases of cell cycle

Resting phase ( G0 Phase)

1. Inter Phase (Divided in to 2 sub phases).
1. G1 Phase
2. S Phase
3. G2 Phase
2. M Phase or Mitosis Phase

G0 Phase: In G0 Phase the cell exist in a quiescent state. G0 phase is viewed as either an extended G1 phase where the cell is neither dividing nor preparing to divide and or as a distinct quiescent stage which occurs outside of the cell cycle.

G0 is sometimes referred to as a "post-mitotic" state since cells in G0 are in a non-dividing phase outside of the cell cycle;

The nerve cells after reaching maturity (i.e., when they are terminally differentiated) become post-mitotic (enter G0 phase) but continue to perform their main functions for the rest of the life.

Inter Phase: The majority of eukaryotic cells spend most of their time in interphase.

In this phase cell performs the majority of its purposes including preparation for cell division. In preparation for cell division it increases its size and number of organelles, and makes a copy of its DNA. Interphase is also considered to be the 'living' phase of the cell, in which the cell obtains nutrients, grows, reads its DNA, and conducts other "normal" cell functions.

G1 Phase (Gap 1):  In this phase the cell grows and functions normally. During this time, a lot of protein synthesis occurs and the cell grows (to about double its original size) - more organelles are produced, increasing the volume of the cytoplasm. If the cell is not to divide again, it will remain in this phase.

S Phase (Synthesis Phase): In this phase the cell duplicates its DNA (via semi-conservative replication)

 G2 Phase (Gap 2):  It is the shortest subphase during interphase in which the cell undergoes a period of rapid growth to prepare for mitosis. It follows the S phase, and occurs during a period of often four to five hours (for human cells). In this phase the nucleus is well defined, bound by a nuclear envelope and contains at least one nucleolus. Although chromosomes have been replicated they cannot yet be distinguished individually because they are still in the form of loosely packed chromatin fibers.

The G2 phase prepares the cell for mitosis (M phase) which is initiated by Prophase

 M Phase (Mitosis): Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei.[1] It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle.

Criteria for Brain Death

For pediatir patients of less than 5 years

The precondition and the Physical examination are similar to adults difference lies in the duration of observation

For 7 days to 2 months children period of observation is 2 examinatin and EEG's searated by atleast 48 hours

For 2 months to 1 year children  examinatin and EEG's searated by atleast 24 hours. 

A repeat examination and EEG are not necessary if a concomittant radionuclide flow study shows no visualization of cerebral arteries

For child of > 1 year - When an irreversible cause exists laboratory testing is not required but an observation period of atleast 12 hours is recommended

Brain Death

Brain Death is defined as "irreversible sessation of all fuctions of entire brain"

Criteria for brain death

Certain preconditions to be excludede prior to proceeding for the tests of brain death

    1. Rule out depressent drug use

    2. Rule out Hypothermia ( Temp should be > 35 Degree Cetigrade)

    3. Rule out Neuromuscular blocking drugs

    4. Rule out metabolic and endocrine disturbances

On physical examination certain criteria should be met to declare brain stem death

    1.  Coma and Apnea must coexist

    2. Absence of Brainstem function should be defined by

        a. Mid position of pupil

        b. Absebce of eye movements induced by oculocephalic and caloric tests

        c. Absence of movements of bulbar musculature including Gag and Cough reflex

       d. Respiratory movements absent with patient  on respirator

   

Parts of the sylvian fissure

The sylvian fissure divides the frontal lobe and parietal lobe above from the temporal lobe below.

Sylvian fissure has two parts.

1. Superficial part

2. Deep part

The superficial part is the part seen to the exterior

The convexity face of the Sylvian fi ssure displays fi ve major arms (rami) that help to define the surface anatomy of the convexity.

The long nearly horizontal portion of the sylvian fi ssure is the posterior horizontal ramus (PHR).

At its anterior end, the anterior horizontal ramus (AH) and the anterior ascending (AA) ramus arise together in a “V” or “Y” confi guration.

At its posterior end, the prominent posterior ascending (PA) ramus and the small posterior descending (PD) ramus branch outward in a “T” or “fi shtail” confi guration.

The anterior subcentral sulcus ( Single arrow) and the posterior subcentral sulcus (Double arrow) form two minor arms that extend superiorly into the frontoparietal operculum to delimit the subcentral gyrus.

One or multiple transverse temporal sulci (Triple arrows) extend inferiorly into the temporal lobe in relation to the transverse temporal gyrus of Heschl.

The deep part has 2 compartments

1. The Spheniodal or Anterior compartment and

2. Operculo insular or Posterior compartment

CT findings in ventriculomegaly

Ventriculomegaly secondary to atrophy

1.  Frontal angle is obtuse

2. widened sulci and cisterns

Ventriculomegaly secondary to NPH

1. ventriculomegaly out of proportion to sulcal enlargement

2. size of the hippocampus is normal and it distingushes ventriculomegaly with NPH to ventriculomegaly secondary to atrophy

Imaging of Hydrocephalus

1. The ratio between the largest width of the frontal horns and the internal diameter from inner-table to inner-table at this level should be greater than 0.5 in the presence of hydrocephalus.

2. Evan's ratio : Ratio of the largest width of the frontal horns to maximal biparietal diameter  is greater than 30% in acute hydrocephalus.

3. Acute frontal angle

4. Temporal horn width >3mm

5. "Mickey mouse" ventricles: Ballooning of frontal horns of lateral ventricles and third ventricle it indicates aqueductal obstruction.

6. Thinned out Corpus Callosum

7. Inferiorly displaced fornix

Delta sign and Reverse Delta sign

These are seen classically in SSS Thrombosis.

On noncontrast CT scan, the classic finding is the delta sign, which is observed as a dense triangle (from hyperdense thrombus) within the superior sagittal sinus. However, this is not specific, since high attenuation in the healthy nonthrombosed sinus can be observed occasionally and is common in neonates because of an elevated hematocrit.
On contrast-enhanced CT scan, the reverse delta sign (ie, empty triangle sign) can be observed in the superior sagittal sinus from enhancement of the dural leaves surrounding the comparatively less dense thrombosed sinus.
The presence of both the delta and reverse delta signs increases the likelihood of the diagnosis.
A false-positive delta sign may occur in a trauma setting because of an adjacent subdural hematoma.
The dural sinus normally may appear hyperdense relative to adjacent tissues. Both the delta and reverse delta signs may need to be present to establish the diagnosis.
Occasionally, the superior sagittal sinus may bifurcate proximal to the torcular herophili, resulting in a confluens sinuum and an empty delta sign without the presence of a venous thrombosis.

Hypothermia in Neurosurgery

1. Mild hypothermia has been used for treatment of TBI, stroke, hepatic encephalopathy, and MI by inhibiting a complex cascade of processes at the cellular level after a period of ischemia.
2. Mild hypothermia is effective for postischemic injury after global anoxia and for lowering the intracranial pressure in various types of brain injury. More studies are needed to further define its role for TBI, ischemic stroke, and repair of thoracoabdominal aneurysms.

Aperture Problem

Each neuron in the visual system is sensitive to visual input in a small part of the visual field, as if each neuron is looking at the visual field through a small window or aperture. The motion direction of a contour is ambiguous, because the motion component parallel to the line cannot be inferred based on the visual input. This means that a variety of contours of different orientations moving at different speeds can cause identical responses in a motion sensitive neuron in the visual system.

The Aperture Problem. The grating appears to be moving down and to the right, perpendicular to the orientation of the bars. But it could be moving in many other directions, such as only down, or only to the right. It is impossible to tell unless the ends of the bars become visible in the aperture.

Motion perception

Motion perception is the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs.

Area V5 seems to be important to the processing of visual motion and damage to this area can disrupt motion perception.

First-order motion perception refers to the perception of the motion of an object that differs in luminance from its background, such as a black bug crawling across a white page.

Second-order motion is motion in which the moving contour is defined by contrast, texture, flicker or some other quality that does not result in an increase in luminance or motion energy in the Fourier spectrum of the stimulus.

visual cortex

The term visual cortex refers to the primary visual cortex and extrastriate visual cortical areas such as V2, V3, V4, and V5.

V1: The primary visual cortex, also the koniocortex (sensory type) located in and around the calcarine fissure in the occipital lobe. It receives information directly from the lateral geniculate nucleus.

V2: Also called prestriate cortex. It receives strong feedforward connections from V1 and sends strong connections to V3, V4, and V5. It also sends strong feedback connections to V1. V2 is split into four quadrants, a dorsal and ventral representation in the left and the right hemispheres. Together these four regions provide a complete map of the visual world. Cells are tuned to simple properties such as orientation, spatial frequency, and color.

V3: The term third visual complex refers to the region of cortex located immediately in front of V2, which includes the region named visual area V3 in humans. It is divided in furthur dorsal V3 and Ventral V3. Dorsal and ventral V3 have distinct connections with other parts of the brain, appear different in sections stained with a variety of methods, and contain neurons that respond to different combinations of visual stimulus. Dorsal V3 may be anatomically located in Brodmann area 19.

V4: It is one of the visual areas in the extrastriate visual cortex of the macaque monkey. It is located anterior to V2 and posterior to visual area PIT. It is unknown what the human homologue of V4 is, and this issue is currently the subject of much scrutiny.

V5: Visual area V5, also known as visual area MT (middle temporal), is a region of extrastriate visual cortex that is thought to play a major role in the perception of motion.

First sense to develop in the fetus

Touch is the first sense to develop in fetus.

The developing fetus responds to touch of the lips and cheeks by 8 weeks and to other parts of its body at 14 week.

The sense of taste may develop by 12 weeks and that of sound at 22-24 weeks.

Unique Mesencephalic Nucleus

The mesencephalic nucleus of the trigeminal nerve is Unique in many aspects. 

It is considered as the only place in the nervous system where the cell bodies of primary afferent fibers are found within the central nervous system rather than in ganglia outside the central nervous system.

The cell bodies located in the mesencephalic nucleus of the trigeminal are actually connected to afferents (sensory fibers) primarily from muscles for chewing.

It is considered as the center for the Corneal reflex though some say the Spinal nucleus as the center for the Corneal reflex.

Jaw Jerk

The jaw jerk reflex is a motor reflex used to test the status of a patient's trigeminal nerve

The mandible is tapped at a downward angle just below the lips at the chin while the mouth is held slightly open. Normally this reflex is absent or very slight. However in individuals with upper motor neuron lesions the jaw jerk reflex can be quite pronounced.

The reflex is MONOSYNAPTIC, with sensory neurons of the trigeminal MESENCEPHALIC NUCLEUS sending axons to the trigeminal motor nucleus, which in turn innervates the masseter.

This reflex is used to judge the integrity of the upper motor neurons projecting to the trigeminal motor nucleus. Both the sensory and motor aspects of this reflex are subserved by CN V.

It is not part of a standard neurological examination, being used rather if there are other signs of damage to the trigeminal nerve.

ONDINE'S CURSE

It also called congenital central hypoventilation syndrome (CCHS) or primary alveolar hypoventilation.

Patients afflicted with Ondine's curse classically suffer from respiratory arrest during sleep.

Till 2006, there were only about 200 known cases worldwide.

The disease used to be classified as a "neurocristopathy"or disease of the neural crest because part of the autonomic nervous system (such as sympathetic ganglia) derives from the neural crest.

Patients generally require tracheotomies and lifetime mechanical ventilation.

Now it is been shown that Biphasic Cuirass Ventilation can effectively be used without the need of a tracheotomy.

An alternative to a mechanical ventilator is Phrenic Nerve Pacing/diaphragm pacing.

TARLOV CYST

These represent one of the common type of arachnoid cyst.

They arise from the posterior rootlet (S2 and S3 most common) and form a dilated nerve root sleeve as a normal variant.

They can cause sacral erosion and may communicate with the thecal sac.

HSV Encephalitis in Children

• In children and neonates, herpes simplex virus type 2 (HSV-2) accounts for 80-90% of neonatal and almost all congenital infections.
• In neonates, HSV-2 typically involves the periventricular white matter and the meninges, with sparing of the medial temporal and inferior frontal lobes.

HSV Encephalitis in Adults

• In adults, herpes simplex virus type 1 (HSV-1) accounts for 95% of all fatal cases of sporadic encephalitis and usually results from reactivation of the latent virus.
• An isolated case report of an immunocompromised adult patient developing HSV-2 infection has been described.
• Adult HSV-1 encephalitis often results from reactivation of latent HSV in the trigeminal ganglion. The virus spreads along the orbitofrontal and temporal meningeal branches of this cranial nerve and then to the anterior and middle cranial fossa. Atypical spread can occur when cranial nerves IX and X are involved. 
• The virus has a predilection for the limbic system, involving one or both temporal lobes, and often involving the hippocampus, parahippocampus, and amygdala. Frontal and parietal spread also can occur.

10 Myths in Neurosurgery

Myth 1: Head elevation is beneficial in the treatment of elevated intracranial pressure.

Myth 2: Hyperventilation (induced hypocapnia) is useful to treat elevated intracranial pressure.

Myth 3: Glucocorticoids are beneficial in the treatment of brain injury.

Myth 4: Antihistamines (H2 blockers, eg, cimetidine) should be used to avoid stress gastritis.

Myth 5: Shaving the operative site reduces infection.

Myth 6: Following anterior cervical discectomy (ACD), a fusion procedure is required.

Myth 7: Congenital disorders such as neural tube defects and hydrocephalus are not preventable.

Myth 8: Primary brain tumors do not metastasize.

Myth 9: Knowledge of neuroanatomy will allow the surgeon to avoid iatrogenic neurological deterioration.

Myth 10: The "Brain" is the surgical domain of the neurosurgeon.

UNINDENTIFIED BRIGHT OBJECTS IN BRAIN

30% to 60% of patients with Type I Neurofibramatosis (NF1)  demonstrate hyperintense lesion on T2-weighted MRI in the basal ganglia, thalamus, cerebellum, and brain stem. These lesion are called un-identified bright objects ( UBO'S).
An association was demonstrated between these lesions and learning disabilities in children with NF1.
Pathology of these lesion showed increased water content but not dysplasia or hamartoma.

PARANEOPLASTIC CEREBELLAR DEGENERATION

It is the most common remote effect of neoplasm affecting the brain.
It is associated with lung, ovarian, and breast Ca and Hodgkin’s disease.
Histopathologically, there is a severe loss of Purkinje cells.
Two main antibodies are found in patient’s sera and CSF; namely Yo and Hu antibodies.
The symptoms usually progress rapidly to severe and symmetric truncal and limb ataxia with dysarthria and nystagmus.
Cerebellar sypmtoms may improve in some patients when causative neoplasms are removed.

Autism and yawning

Children with autism spectrum disorder are not as susceptible to contagious yawning as other children.

(Source: Senju, A., et al., Absence of contagious yawning in children with autism spectrum disorder, Biology Lett., August 14, 2007 (DOI 10.1098/rsbl.2007.0337).

Egaz Moniz, Antonio

Nobel Prize winner Antonio Egaz Moniz, who introduced the prefrontal lobotomy, was the Portuguese ambassador to Spain in 1917. (Source: Meyers, M.A., Happy Accidents. Serendipity in Modern Medical Breakthroughs, New York: Arcade Publishing, 2007.)

He also introduced the technique of cerebral angiography.

Speed of Transmission

Information travels in the nerves at speeds up to 268 miles per hour (429 kilometers/hour).

Sleep, Death and Dreams

1. In Greek mythology Sleep (Hypnos), Death (Thanatos), and Dreams (Oniros) were children of the goddess Night (Nyx)
2. Neglect or Forgetfulness (Lethe) and Pain (Algos) were grandchildren of the Night (Nyx). (Source: Ture et al., The art of alleviating pain in Greek mythology, (Neurosurgery, 56:178-185, 2005.)

Neuro Philately in India

Several countries have issued postage stamps with pictures of famous neuroscientists.

India till date don't have a postage stamp in relation to neuroscience but for a five rupee stamp about Drug addiction.

Missing 1st Spinal nerve

The first cervical dorsal spinal nerve and dorsal root ganglia are missing in 50% of all people. (Source: Schwartz, E.D. and Flanders, A.E., Spinal trauma: imaging, diagnosis, and management, Philadelphia: Lippincott Williams & Wilkins, 2007.)

Record for Stay without sleeping

In 1965, Randy Gardner set the world record for staying awake: 264 continuous hours (about 11 days).

In Biopsychology (by J.P.J. Pinel, Boston: Allyn and Bacon, 2000, p. 322), the record for time awake is attributed to Mrs. Maureen Weston. She apparently spent 449 hours (18 days, 17 hours) awake in a rocking chair.

The Guinness Book of World Records [1990] has the record belonging to Robert McDonald who spent 453 hours, 40 min in a rocking chair.

Lyme disease

Lyme disease, or borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia.

Even pets (and wild animals) can get Lyme disease. Dogs, cats, horses, mice, cattle, deer, squirrels, opossum and raccoons can be infected. Many wild animals infected by the bacteria that cause Lyme disease do not show any symptoms. Dogs, however, may develop a fever and have pain in the joints. This can cause them to limp when they walk.

US President George W. Bush was treated for Lyme disease in August, 2006.

Cerebral Cortex

The human cerebral cortex has an area of about 2.5 square feet, has 25 billion neurons, is interconnected by over 100,000 kilometers of axons and receives 300 trillion synapses.

The Edwin Smith surgical papyrus, written about 1,700 B.C., contains the first recorded use of the word "brain."

In 1891, Wilhelm von Waldeyer coined the term "neuron."

Collodion

Collodion is a solution of nitrocellulose in ether or acetone, sometimes with the addition of alcohols. Its generic name is pyroxylin solution. It is highly flammable. As the solvent evaporates, it dries to a celluloid-like film.

It was discovered about 1846 by the French chemist and writer Louis Ménard.

Celloidin is a pure type of pyroxylin used to embed specimens which will be examined under a microscope.

Cytoarchitectonics

Cytoarchitectonics connotes the study of the cellular composition of the body's tissues under the microscope. Applied particularly to the study of the central nervous system, cytoarchitectonics is one of the ways to parse the brain (along with gross anatomy, topography, receptor-binding autoradiography, immunohistochemistry, etc.), by obtaining sections of the brain and staining them with chemical agents that reveal how nerve cell bodies (or neurons) are "stacked" into layers.

The study of the parcellation of nerve fibers (primarily axons) into layers forms the subject of myeloarchitectonics an approach complementary to cytoarchitectonics.

The birth of the cytoarchitectonics of the human cerebral cortex is credited to the Viennese psychiatrist Theodor Meynert (1833-1892), who in 1867 noticed regional variations in the histological structure of different parts of the gray matter in the cerebral hemispheres.

Einstein's brain

Einstein's brain was removed, weighed and preserved by Thomas Stoltz Harvey, the pathologist who performed the autopsy on Einstein. He claimed he hoped that cytoarchitectonics would reveal useful information.

Harvey injected 10% formalin through the internal carotid arteries and afterwards suspended the intact brain in 10% formalin. Harvey photographed the brain from many angles. He then dissected it into roughly 240 blocks (each about 10cm3) and encased the segments in a plastic-like material called celloidin.

Albert Einstein's brain

The brain of the great physicist Albert Einstein weighed 1,230 grams. This is far below the average brain weight of 1,400 grams.

Scientific studies have suggested that regions involved in speech and language are smaller, while regions involved with numerical and spatial processing are larger. Other studies have suggested an increased number of Glial cells in Einstein's brain.

Some interesting things about Synapses

A synapse is a functional membrane-to-membrane contact of the nerve cell with another nerve cell, an effector (muscle, gland) cell, or a sensory receptor cell.
The term "synapse" was coined by Charles Scott Sherrington in 1897.
The distance separating two neurons at a synapse is 20-40 nanometers.
There are basically 2 types of symapses.
1. Chemical synapse
2. Electrical synapse.

Loss of taste

Most of us know that loss of vision is called blindness and loss of hearing is called deafness.

Some may also know that loss of smell is called anosmia.

Many doesn't know what loss of taste is called.

A decrease in ability to taste is called HYPOGEUSIA, and a total loss of taste is termed AGEUSIA.

what is the fifth taste?

Every one knows that there are five primary taste sensations.

1. Sweet

2. sour

3.Bitter 

4. Salt

Did you ever thought what could be the fifth taste

The 5th primary taste sensation is called "umami."

It is a taste taste that occurs when foods with glutamate are eaten.

The red eye of Photography

Do you know what causes "red eye" when you take a flash photograph?

The choroid is a layer of tissue at the back of the eye that contains a large number of blood vessels. Red eye usually happens when a flash photograph is taken in dim light. In dim light, the pupil of the eye is dilated and allows plenty of light to enter the eye. Red eye is caused when the choroid reflects the light of the flash. The pupil does not constrict fast enough to reduce the amount of light that enters the eye. Therefore, the flash of light reflects back out of the eye and is recorded on film. Some cameras use red eye reduction methods that send out a short burst of light before the film is exposed. The brief burst of light allows the pupil to constrict and thus reduces red eye.

Medicine logo

A staff or wand with either one or two snakes wound around it is often used as a symbol of medicine. The single snake staff is attributed to the ancient Greek God Asclepius (Aesculapius or Asklepios); the two snake wand, called a caduceus, is attributed to the mythological character Hermes (Mercury). 

Some more interesting facts

The optic nerve is the thickest of the cranial nerves and is made of about 1,200,000 fibres. Approximately it  carry 38% of all nerve fibers that enter or leave the brain. Where as the abducens nerve is the thinnest and comprises of about only 3,700 fibres.

Some thing interesting

Hi friends I have found some thing interesting

You have probably experienced "deja vu" -- the feeling that something is familiar to you. Did you know that some people experience the feeling that something is unfamiliar? This is call "jamais vu."

Other feelings that sometime occur:

deja entendu = already heard
deja eprouve = already experienced
deja fait = already done
deja pense = already thought
deja raconte = already recounted
deja senti = already felt, smelt
deja su = already known (intellectually)
deja trouve = already found or met
deja vecu = already lived
deja voulu = already desired

Hi Good Morning

Hi friends a very good morning to all.

KRRISH

The cool cloud

The Brain Game

Everyone wants to stay in shape, and now you can keep your brain in shape as well with the Brain Trainer. The Brain Trainer is a fun, hand-held game that allows you to compete against yourself in order to keep yourself mentally fit. This little gadget performs tests that stimulate your brain by working the frontal cortex. This is the part of your brain that controls creativity, memory, and communication.

So if you find yourself forgetting things or losing your train of thought easily, you may just need to exercise your brain. The Brain Trainer was invented by a neuroscientist in Japan. It is designed to take you through a series of programs that quickly stimulate your frontal cortex in order to enhance mental agility. The programs include tests in which you add, subtract or multiply as fast as possible, count as quickly as you can, or add a series of numbers sequentially. There are also tests for memorization and recalling as many numbers as possible.

When you are feeling like you need a mental boost just pull out your handy Brain Trainer. As you progress through the programs the device also keeps track of you score and time for each session so you can always compete against yourself and try to increase your brain power each time you play. The Brain Trainer runs on 2 AAA batteries.

Start increasing your mental capacity and get your Brain Trainer

The cattle of Munnar

Answers

1. Answer: ACDE

DISCUSSION: Many skulls from the Neolithic period have been found, some of which contain cranial defects with evidence of bone healing, indicating that these individuals underwent trepanation during life and survived the operation. The earliest known writing dealing with surgical topics is the Edwin Smith papyrus. In the works of Hippocrates is the first written account of trepanation. During the second half of the nineteenth century, general anesthesia was introduced and the principles of asepsis were developed. These steps were important for all areas of surgery, including neurosurgery. In addition, it became recognized that certain areas of the nervous system were especially important for certain neurologic functions and that intracranial and intraspinal abnormalities might be localized by the history and neurologic examination findings, thus providing a more specific target for neurosurgical exploration through the small bony openings to which surgeons were restricted at the time. Victor Horsley of London was the first surgeon to prepare himself specifically for surgery of the nervous system and to concentrate his efforts in that area.

2. Answer: C

DISCUSSION: Harvey Cushing (1869–1939) laid the groundwork for much of what is done in neurosurgery. For example, he standardized operative procedures and introduced many techniques and instruments that are still in use. He also made careful and detailed studies of intracranial tumors and established their classification. By his own multifaceted career and through his many students from around the world he influenced the development of neurosurgery to a degree not equaled before or since.


3. Answer: BDE

DISCUSSION: MRI has proved to be a better modality than CT for evaluation of disease of the central nervous system (CNS), such as diseases at the base of the skull (particularly the sellar and cerebellopontine angle cistern regions) and for most tumors, white matter disease (e.g., multiple sclerosis), early stroke, congenital abnormalities, vascular malformations, and spinal disease. New techniques of MRI such as fast spin echo (FSE) pulse sequence have been developed to detect mesial temporal sclerosis, which is the most common cause of intractable complex partial seizure. Differentiating pure compression fracture from metastatic disease of the vertebral bodies in a patient with known primary cancer is also possible by new MRI technique; however, for patients with certain types of metal (pacemaker, surgical clip, or foreign body, which may move in the magnetic field and cause injury to the patient or significant artifacts) within the bodies, MRI is contraindicated.

4. Answer: ACDE

DISCUSSION: Diffusion-weighted MR is a new development in MR applications and is sensitive to microscopic motion of water protons (Brownian motion). Initial applications have involved imaging of early stroke and neoplasia. Early evidence also suggests that diffusion-weighted imaging can differentiate tumoral edema from tumor and identify the nonenhancing part of the tumor. Doppler sonography, MRA, and CT angiography (CTA) are all useful for evaluating the stenotic condition of carotid bifurcation noninvasively. However, sonography is very operator dependent, and MRA commonly overestimates the degree of carotid stenosis resulting from the turbulence, dephasing at points of stenosis or irregularity. CTA obtained by spiral or helical CT has a good correlation rate with carotid angiography (92%). Conventional carotid angiography remains the most accurate imaging modality for evaluation of the stenosis of carotid bifurcation. Although CT and MRI have taken the place of myelography in evaluating neurologic diseases, it is still useful in detecting diffuse subarachnoid seeding, which may be difficult to identify on MRI. The bone detail and calcification are poorly identified on MR, so in a patient with facial trauma, CT is a better modality than MR. With MRS, metabolites within a selected region of interest (ROI) can be investigated, and spectral peaks that reflect the concentrations of the metabolite within the ROI can be obtained. The metabolites include lactate, neuronal marker (NAA), phosphorus metabolites, creatine, and choline. Reduction in the NAA level and elevation in lactate level could be noted in acute stroke.


5. Answer: ABCD



DISCUSSION: In children, brain tumors are more commonly situated below the tentorium than above it. In adults, the reverse is true. Cytologic examination of CSF may provide critical diagnostic information in a patient with meningeal carcinomatosis or subarachnoid spread of a primary brain tumor such as a medulloblastoma, but in most instances CSF examination is not of significant value. Furthermore, in a patient with a brain tumor lumbar puncture may be dangerous; it may promote brain herniation. If there has not been a surgical breach of the dura mater, primary brain tumors seldom spread to areas outside the intracranial and intraspinal compartments. Most gliomas, including astrocytomas, cannot be cured by surgical resection. The pilocytic astrocytoma of the cerebellum and the optic nerve glioma are exceptions to that rule. Neoplasms of astrocytic, oligodendroglial, or ependymal origin vary histologically along a spectrum from benign to malignant, with no sharp dividing line. Furthermore, even the most benign-looking ones tend to recur after surgical resection.

Hi friends

Hi friends. Good aftenoon.
Its a busy day to me. Lots of work. By evening i will publish the answers to the yesterdays questions.
Bye.

6th June 2008

1. Which of the following are true about the history of neurosurgery?
A. The history of trepanation dates back to the Neolithic period.
B. The earliest known writing dealing with surgical topics is the Ebers papyrus.
c. The writings of Hippocrates contain the first recorded descriptions of trepanation.
D. The three key developments that were necessary to permit successful intracranial and      intraspinal surgery were anesthesia, asepsis, and the concept of localization
     of different functions  in different areas of the nervous system.   
E.Victor Horsely of London was the first surgeon to specialize in neurosurgery.

2. The neurosurgeon who has had the most profound influence on the development
     of neurosurgery is/are
A. Fedor Krause of Germany.
B. William Macewen of Scotland.
C. Harvey Cushing of the United States.
D. Egas Moniz of Portugal.
E. Goeffrey Jefferson of England.

3.Which of the following conditions can be evaluated by magnetic resonance imaging (MRI)?
A. Stroke is suspected in a patient with a cardiac pacemaker.
B. Computed tomography (CT) shows a skull base tumor.
C. A coma patient with CT-demonstrated subarachnoid hemorrhage and an aneurysmal clip.
D. A patient with intractable complex partial seizure.
E. A lung cancer patient whose plain film of the lumbar spine shows a compression fracture of      the L2 vertebral body.

4.Which of the following statements about neuroradiologic imaging modalities is/are correct?
A.Diffusion-weighted MRI can differentiate tumor from edema and identify the nonenhancing     part of the tumor.
B. For evaluating the stenosis of the carotid bifurcation, MR angiography (MRA) is the most      accurate imaging modality.
C. Myelography is still useful in detecting some diffuse spinal disease such as cerebrospinal fluid     (CSF) seeding.
D. For evaluating the bony detail of patients with facial trauma, CT is a better imaging modality      than MRI.
E. Decreased amount of N-acetyl aspartate (NAA) and increased amount of lactate can be shown      in the MR spectroscopy (MRS) of a patient with acute stroke.

5.Which of the following are true about intracranial tumors?
A. The most common location of brain tumors of childhood is the posterior cranial fossa.
B. With few exceptions, examination of the CSF is of no value in the diagnosis of an intracranial      tumor.
C. Even the most malignant of primary brain tumors seldom spread outside the confines of the      central nervous system (CNS).
D. The majority of astrocytomas can be cured surgically.
E. Primary neoplasms of astrocytic, oligodendroglial, or ependymal origin represent gradations      of a spectrum from slowly growing to rapidly growing neoplasms.







    

MCQ's in Neurosurgery

Hi.
Dear friends from today I will post some important MCQ's in Neurosurgery every day.
I wll try to give the answers next day. Interested can answer and comment. Discussions are welcome.

My first blog

Hi Every one.
This is my first blog.
I have to know a lot more about blogging.
I would like to keep this open to discussions on Neurosciences as I am very much interested on Neurosciences.