Epilepsy surgery: just what is it?

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Let us divert our attention for a few minutes to the topic of epilepsy surgery. Usually when one talks about epilepsy and its treatment, one thinks about medications. You are right, most of the patients with epilepsy shall have their seizures controlled by anti-epileptic drugs. However there are a few patients who have what we call medically refractory epilepsy, that is they have seizures which are refractory to anti-epileptic drugs (even if you use multiple drugs their seizures remain uncontrolled). Usually these are the patients whom we consider epilepsy surgery on.

So what is epilepsy surgery and what does it involve. In simple terms, we first try to map the seizures coming from the brain. By mapping I mean, we try to determine where exactly in the brain the seizures originate from (that is the seizure focus). Once we determine the seizure focus and are reasonably sure that all the seizures come from that focus only, then we open up the skull and the neurosurgeon resects that focus out ( kind of chopping off that part of the brain from which the seizures arise, once you remove the focus, the patient ideally should become seizure free and may be even able to come off his seizure medications).

While this procedure sounds good, it is way more complicated than what I explained above. First off all to meet the criteria for epilepsy surgery, a patient  should meet some criteria. What are these? Well first and foremost, we should be able to identify the seizure focus and be reasonably sure that all the seizures come from that very focus only. How do we do this you may ask. Well usually the patient is admitted for video-EEG study. We hook the patient to the EEG monitor and record the seizures. From the EEG we are able to localize the seizure focus. At times though the seizure focus cannot be identified for sure from the surface. In that case we do what is called intracranial monitoring. It is similar to the EEG except here we open up the skull and place the recording electrodes right on the surface of the brain itself.

Once we have localized the seizure focus, we have to make sure of a couple of things. One does that part of the brain serve any useful function? We are mostly worried about memory and speech issues. Secondly if it does house some memory or speech function, would it lead to any deficits if we take that part of the brain out. You do not want the patient to wake up from the surgery and not able to talk or have problems with memory. We test for this by a special test called the WADA test. This test helps us in determining the memory and speech localization in the brain.

Your doctor may also order additional tests again to aid in localizing the seizure focus. Some of these tests include special scans like the PET (positron emission tomography) and SPECT (single photon emission computed tomograpy) scans.

I hope this brief overview of what epilepsy surgery involves shall be helpful to some of you, we can go into more details if any of you requests it.

Nitin Sethi, MD

Transient ischemic attacks or TIA’s

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Let us talk about transient ischemic attacks or TIA’s here. What does it mean when your doctor tells you that you had a TIA?

TIA or transient ischemic attack as the name suggests means that one has an episode of transient ischemia to the brain. Kind of like a mini-stroke except that for it to be called a TIA, the neurological deficits should reverse completely. Let me explain this further. Suppose you have an episode of sudden weakness of the right side of the body (arm and leg) and at the same time, your speech is off. This presentation is mostly likely due to ischemia (lack of blood flow) in the left middle cerebral artery of the brain. Now this can act out in 2 ways. One you are recover completely, often within a few minutes to an hour at most. That means the ischemia was transient and that you are not left behind with any neurological deficits (no weakness and speech is back to normal). This would then be called a TIA involving the left middle cerebral artery.

The second possibility is that you do not recover at all, or do recover to some extent (after been treated in the hospital for acute stroke). Here the patient has stroked out. If you do an MRI of the brain, you shall see evidence of acute stroke. In a TIA, the imaging shall be normal as the recovery is complete.

So now that we understand what a TIA means, let us talk about the different types of TIA’s. One of the most common TIA is what we call transient monocular blindess or Amaurosis Fugax. This is a special type of TIA in which there is sudden lack of blood flow into the ophthalmic artery (branch of the internal carotid artery in the neck). As there is lack of blood flow in the artery which supplies the retina, patients notice sudden onset of loss of vision in one eye (remember I said monocular). Ususally they describe it as if a curtain suddenly descended in front of that eye. This monocular blindness lasts for a few seconds to minutes and then goes away.

One can have other types of TIA’s depending upon which blood vessel in the brain has a sudden episode of ischemia. So you have patients who present with history of transient weakness in an arm or leg, transient speech difficulties, transient numbness in an arm or leg, transient episode of dizziness or unsteady gait etc etc.

So are TIA’s important and do they need to be treated is the next question? Usually a TIA shall affect the patient and make him or her visit the ER. Some patients though may ignore the episode, since now they are back to normal and just go on with their lives.

A TIA is a warning sign for stroke. It usually is a sign that a stroke is imminent. The brain has suffered an episode of dysfunction even though transient. Here in lies the importance of recognizing a TIA and seeking medical attention for it. Studies have shown that major strokes may soon follow a TIA.

What to do if you have a TIA?

1) well first things first it is important to recognize a TIA and give it its due importance. If you are having stroke like symptoms call for help and dial 911 and be taken to the nearest hospital for evaluation. You do not know at the onset whether this is going to be a TIA and that you shall recover completely without any intervention or that you are going to stroke out. Remember time is brain, the more time you waste, the more likely you shall suffer damage to the brain from a stroke.

2) If you are having a TIA, it is likely that the symptoms shall have abated by the time you reach the ER. Well and good, as you rather have a TIA than a stroke.  When patient’s present to the ER with a TIA, doctors usually admit them for a thorough stroke evaluation. We have a unique opportunity to try to identify your risk factors for stroke and modify them, so that you do not have a future stroke. Your doctor may run many tests on your brain (MRI, carotid dopplers to look to see if your neck vessels are patent) as well as on your heart ( as some strokes and TIA’s come from the heart. Tests like holter monitor and ECHO).

We can also prescribe you medications to make your blood thin, medications like aspirin which may reduce the risk of a future stroke.

So remember to recognize a TIA and seek help promptly. A stroke prevented is a brain saved.

Dr. Sethi

Tremor: what is essential about it?

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So let us discuss the diseases which can present with tremors.

1) Drug induced tremors: certain drugs can induce a tremor like I stated ealier. Drugs used to treat asthma (inhalers) and anti-epileptic drugs like valproic acid may induce a tremor in the hands.

2) Benign essential tremor: this as the name suggests is a benign tremor. Patients who have benign essential tremor usually have a postural tremor in their hands but may also have a head and speech tremor. They do not have any underlying neurodegenerative disorder and usually the tremor is not disabling and progressive. As the tremor is not disabling it may not need to be treated unless it causes social embrassement to the patient. Patients who have classical essential tremor notice that their tremor becomes less prominent if they consume alcohol (tremor is alcohol responsive).

3) Cerebellar tremor: patients who have cerebellar involvement (example if you have cerebellar tumor or diseases that involve the cerebellum such as multiple sclerosis) may also have a prominent kinetic (intentional) tremor.

4) Parkinson’s disease: patients who have Parkinson’s disease have a prominent resting tremor. This tremor is most prominent when their hands are at rest and becomes less prominent when they start to use their hands.

Treatment of tremors: like I mentioned earlier, not all tremors need to be treated. We usually treat tremors when they become disabling or socially embrassing to the patient. There are different classes of drugs that are effective for tremor of Parkinson’s disease, cerebellar tremor and essential tremor. Your doctor shall help in deciding what kind of medication may work the best for you. Sometimes if the tremor is particularly disabling and unresponsive to medication, it may respond to neurostimulation (deep brain stimulation). I shall discuss this in a separate post.

Dr. Sethi

Tremor: its essentials and management

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In this post I shall talk a little bit about tremors. What exactly is a tremor you may ask. The way we define tremor in neurology is a rhythmic oscillatory movement across a joint. One may have a hand tremor (your hands shake), leg tremors, head tremor and even speech and tongue tremors. One way to classify tremors is to divide them into physiological and non-physiological tremor.

Physiological tremor is present in each and every one of us. If you hold your hands straight out and balance a sheet of paper on it, you can see the paper shaking a little. This is due to the physiological tremor in our hands. We all have it and the thinking behind it is that it is due to cardioballistic motion. Now suppose you go and have a large (I think they call it venti size) Starbucks coffee and repeat the above test again. You shall find that your tremor is now more prominent, this enhancement of the physiological tremor by coffee and some drugs like aminophylline is what is called enhanced physiological tremor. Physiological and enhanced physiological tremors do not need to be treated as they do not disturb the patient in any way. You may ask the patient to cut down on his coffee though.

Non-physiological tremor: as the name suggests these tremors are pathological. One way to classify pathological tremors is on the basis of how they present. So one may have a tremor which is most prominent when the hands are completely at rest and is not present once the hands come into motion (or start doing some activity). This is called a resting tremor (tremor at rest) and is classically seen in patients with Parkinson’s disease. Other tremors are prominent only when the hand is engaged in some action and hence those tremors are called action tremor.

When a patient comes to us for the evaluation of a tremor what we look for is whether the tremor is isolated (meaning there are no other manifestations apart from the tremor) or whether the tremor is a part of a larger neurological syndrome. We want to rule out neurodegenerative conditions like Parkinson’s disease which may present with tremor. Secondly we want to know whether the tremor shall remain static or whether it is going to worsen as time goes by. Then we try to classify the type of tremor and try to identify its etiology. Is it drug induced? What are its exacerrbating factors and what factors make the tremor become less prominent? Does the tremor become less prominent after consuming alcohol? Does the tremor run in the family (meaning is there a family history of tremors)? What does the tremor involve: just the limbs or also the head and speech?

In my next post I shall talk about the management of tremors.

Dr. Sethi

Controlled eating Vs mindless munching

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Controlled eating Vs mindless munching

Nitin K Sethi, MD

 

        Comprehensive Epilepsy Center, Department of Neurology, NYP-Weill Cornell Medical Center, New York, NY (U.S.A.)

 

I read a very interesting article in the health section of the Wall Street Journal this Friday. As it has something to do with the brain, I thought I shall talk about it here. It was titled ” putting an end to mindless munching” and basically talks about how little attention we pay to food and to the very act of eating. Most of the times when we sit down to eat, we are in a hurry, hurry to get back to the job, hurry to go pick up the kids, do the laundry etc etc, you get the point. And when we do eat at leisure ( as for enjoying a meal with family or friends like at dinner) we still do not pay attention to the food and how we eat. We are at that time too engrossed in our conversation, eating and talking at the same time. How many times do we actually try to savour the smell and taste of the different ingredients that form our food. Biting into the freshy juicy tomato, enjoying the subtle tangy flavor of the olives on the side, letting the spices soak into the tongue before rushing to toss more food into our mouth.

This as the article points out leads to mindless munching. Mindless munching because your brain is not conscious of the act of eating. You see eating like walking occurs on a subconscious level in our brains. The act of eating is hardwired into our brains. You do not have to teach a child how to eat. It comes naturally to him. This hardwiring of the brain is seen for other acts like walking, when we are walking it is occuring naturally. You are not consciously aware of every step you take, you take one and then another–it is smooth, without the conscious participitation of the brain.

But what does this mindless munching lead to? As the article says, in some it is a major cause of obesity. You are eating without thinking about the food, not even about its taste so waht to talk about its quantity. These people end up overeating and becoming obese.

Controlled eating can help people trying to lose weight. What do I mean when I say controlled eating. I mean making yourself aware of the food which is in front of you and which you are putting into your mouth. Take a small bite, use a small spoon and savour the first taste. Think how hungry you were, or if you are not so hungry think about it too.  Think how much you were looking forward to this good food. Let the taste hit you, as your saliva mixes with the food and coats it across your tongue. The tongue is a wonderful organ, richly supplied with taste buds which are tuned to differentiate different tastes: sweet, salty, sour and bitter. It is richly innerverated by sensory nerves which convey these sensations to the gustatory center of the brain. At the same time allow your nostrils to smell the food. Let the exotic smells drift to the olfactory cortex of your brain. The olfactory cortex is one of the oldest parts of the human brain and there is a reason why it is there in all animals.

As you do this controlled eating, you automatically shall know when and how much to eat. It shall prevent overeating and moreover you shall enjoy your food more. The hypothalamus in the human brain houses the satiety center. It consists of a group of cells in the ventromedial hypothalamus that when stimulated suppress a desire for food. Controlled eating shall give the hypothalamus cells time to get signals and thus suppress the desire for further food.

Controlled eating Vs mindless munching : I shall let you all do the math

Happy controlled eating everyone.  All this talk got me hungry!!

Address for Correspondence:

NK Sethi, MD

Comprehensive Epilepsy Center

Department of Neurology

NYP-Weill Cornell Medical Center

525 East 68th Street, York Avenue

New York, NY 10021

Fax: 212-746-8984

Email: sethinitinmd@hotmail.com

 

Absence seizures and staring spells

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Let us talk about another kind of childhood seizures called Absence seizures or at times Petit Mal seizures. Childhood absence epilepsy as the name suggests starts off in childhood. The seizures are subtle and thus may escape detection from even doting parents. Most of the time, it is the teachers in school who first report that the child at times is noted to “stare” or “daydream”. At times the school grades start falling and this brings the child to medical attention.

Absence seizures as the name suggests are short duration seizures where-in the child is “absent”. By that I mean that for the short time (few seconds to a minute)  during which the child is having a seizure, he or she is not aware of the immediate surroundings. This is because even though an Absence seizure is brief, it is a generalized seizure (meaning the whole brain has a seizure and thus malfunctions for that few seconds). It is different from a generalized convulsion in that you do not seek the violent shaking movements of the arms and legs. Thus it is subtle and may escape detection in the earlier years.

Absence seizures need to be treated. The reason for this is that the seizures are frequent, at time hundreds in a day and these frequent seizures impair the cognitive development of the child. The diagnosis is relatively straight forward and your physician might make it on the basis of a good history. An electroencephalogram (EEG) study may shown the characteristic EEG pattern of Absence epilepsy confirming the diagnosis. An imaging study is usually not needed unless there are some atypical features in the presentation.

Once the diagnosis is made, Absence seizures can be readily controlled with anti-epileptic drugs. Two drugs are commonly used for this kind of epilepsy: ethosuximide and valproate. Children usually do not need to be on anti-epileptic drugs for prolonged length of time and they usually outgrow these seizures by the time they reach the age of 17.

Dr. Sethi

Brain tumors primary Vs secondary (what we know and what we don’t)

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This is a continuation of my earlier post on brain tumors where I went over the classification of brain tumors, their presentation (what signs and symptoms they present with) and briefly discussed about their management.

Primary brain tumors that is tumors which arise from the brain itself need to be differentiated from secondary brain tumors or metastatic spread of tumor to brain (this refers to a tumor which arise somewhere else as for example in the lung and then spreads to the brain. That is the primary site of the tumor is the lung and then it has metastasis to the brain). Various tumors can spread to the brain but the most common among them are:

1) Lung tumor–most common cause of lung tumor is smoking and it commonly spreads to the brain. Infact many times it is first detected only when it has spread to the brain. that is the time the patient either has a seizure or develops weakness on one side of the bogy. When a CT scan or MRI scan of the brain is done a tumor is found and when further investigations are done like Chest X-ray and CT scan of the chest the primary is found to be the lung. Lung tumor may produce multiple metastatic lesions to the brain (by that I mean there are commonly more than one lesion found when the brain is imaged). How does lung tumor spread to the brain you may ask. Well the most common route of spread is what is called the hematogenous route (meaning that some tumor cells from the lung enter the blood stream and are carried to the brain where they develop into secondary tumors).

2) Breast cancer: also commonly spreads to the brain and can present with multiple metastatic lesions. As you can imagine the prognosis is poor once there is evidence of metastatic disease. Thus oncologists (doctors who treat cancer) like to treat cancers aggressively so that they do not spread further and cause widespread disease).

3) Renal cell carcinoma: renal carcinoma may also spread to the brain.

4) Thyroid cancer

5) Colon cancer

6) Choriocarcinoma: choriocarcinoma is usually fulminant and has the potential for causing hemorrhagic brain lesions (meaning that the metastatic lesions in the brain are prone to bleeding).

7) Melanoma: malignant melanoma is frequently seen in the west. It too has the potential for causing hemorrhagic brain metastatic lesions. Hence it is imperative that you follow closely with your doctor if you are diagnosed with melanoma.

As you can imagine the treatment varies if you have a primary brain tumor versus if you have a secondary brain tumor. Treatment decisions also vary depending upon whether you have a solitary brain tumor versus if you have multiple metastatic lesions in the brain. The treatment also depends upon the site (location) of the tumor in the brain. Let me explain this a little further. If the tumor is in a part of the brain which can be easily accessed surgically, is small in size and does not involve any eloquent area of the brain then it more likely that it can be removed surgically. What do I mean by eloquent area of the brain. By eloquent I mean parts of the brain which perform vital functions. So if the tumor involves the speech center of the brain or lies very close to the area which controls the movement of the hand and leg or involves the area of the brain which controls vision, then you can understand that if the surgeon decides to remove it, more than likely the patient has awake from the surgery and be not able to speak or have weakness on one side of the body or may not be able to see. Thus surgical options are limited when tumors involve the eloquent cortex.

Primary brain tumors like glioblastoma multiforme (GBM) rarely ever metasize outside the brain. By this I mean it has been seen that primary brain tumors ususally remain confined to the brain itself and do not spread outside. That said and done, this is not a hard and fast rule and there are cases documented in which a primary brain tumor has spread outside the brain. Primary brain tumors though may spread via the white matter tracts to other parts of the brain and also spread via the cerebrospinal fluid (CSF). So sometimes one may have what we called a multi-centric primary brain tumor. As there are multiple lesions in the brain, this has to be differentiated from a secondary brain tumor (a tumor from outside that has spread to the brain).

Thus usually whenever someone is diagnosed with a brain tumor, multiple other tests are done apart from a MRI brain to rule out a secondary tumor. These include a CT scan of the chest (rule out lung cancer), CT scan of the abdomen and pelvis as well as a bone scan. These investigations also help in determining the spread of the disease and this information is vital in treatment decision making process.

 Dr Sethi

MRI white matter lesions: does it represent MS?

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MRI white matter lesions

Many times I get consulted by patients or their relatives when their MRI brain report reads multiple scattered white matter lesions seen. The radiologist’s report usually further reads that these can be seen in primary demyelinating conditions like multiple sclerosis or in vascular disorders. Patient’s and caregivers are naturally worried when they get this MRI report and do not know what to do and how to proceed further. So I thought that here I shall talk about these white matter abnormalities seen on the MRI. What is their significance? Do they represent evidence of multiple sclerosis?

White matter signal changes on the MRI essentially means that on the MRI, the white matter  showed some scattered bright spots. White matter in the brain refers to the fiber tracts that carry information to and fro from the brain.

My first question when somebody asks me what next and what does this mean is to ask them why was the MRI done in the first place. If the MRI was done because there was a clinical suspicion of multiple sclerosis then these white matter lesions may indeed have significance and may represent radiological evidence of MS plaques. Let me explain this with an example. You go to your doctor, you have signs and symptoms that suggest MS (example you may have had an attack of optic neuritis), when the doctor examines you he is able to elict signs in the examination compatible with a diagnosis of MS, then he orders an MRI to see if you do have evidence of white matter lesions in the brain. In a case like this the presence of white matter lesions/ signal changes in the MRI is obviously important. Here it likely does suggest the presence of MS. That said and done I again want to re-emphasize that the diagnosis of MS is made on the basis of clinical history of previous attacks, CSF (spinal fluid) examination and MRI, not just on the basis of the MRI alone. Also there are certain criteria which have to be satisfied on MRI to make a definite diagnosis of MS. These radiological criteria for MS include the number of lesions on  the MRI, their location and their size.

Thus it is important to remember that a person who is noted to have white matter lesions on a brain MRI does not necessarily have MS. White matter lesions can be seen in numerous other conditions and they are more commonly seen as we grow older. The thinking behind this is that they represent microvascular ischemic changes in the brain (the smaller caliber blood vessels in the brain showing signs of ischemia or decreased blood flow). Hence these white matter abnormalities on MRI are more commonly seen in patients who have microvascular and macrovascular risk factors such as a history of hypertension, diabetes and high cholesterol (dyslipidemia/ bad lipid profile).

White matter signal changes on MRI may also be seen in patients who have infectious and other inflammatory conditions. They have been reported in the MRI of patients with a history of migraine headaches (migraine too is a vascular disorder and that may explain the connection).

So I want to end by saying that the presence of these white matter signal changes on brain MRI has to be correlated to the history, clinical examination and other ancillary investigations. Your doctor shall help you in going about this in a methodical manner. I repeat these white matter lesions do not suggest MS in each and every case they are found.

 Dr. Sethi

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Your brain on religion

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Just some random thoughts on the neuroscience behind religion. What is religion ? How are our religious beliefs generated? Do we have a center in the brain dedicated to religion (is there a religion center in the brain?) Role of temporal lobe and limbic structures in religion. Some patients with temporal lobe epilepsy are hyperreligious. Does the temporal lobe house the religion center of the brain?

I shall be musing about these thoughts further.

Dr. S