Narcolepsy Vs idiopathic hypersomnia-do we need to care?

Two half days a week I see patients in the sleep center. One of the reasons patients come to see me is for excessive daytime sleepiness (EDS). Patients may voice the above complaint in different ways. Some say [Dr. Sethi my biggest problem is that I feel sleepy during most of the day. I find it hard to concentrate at work or my mind feels "dull"]. Others may say they find it difficult to wake up in the morning in time for work or college. The history may be more worrisome: the patient may have fallen asleep while driving. So how does one differentiate between the various causes of EDS? In this post I shall touch on these very topics.

The various causes of EDS can be broadly listed as follows:

1. Untreated sleep disordered breathing: Obstructive sleep apnea (OSA), Central sleep apnea (CSA), Mixed sleep apnea (MSA).

2. Poor sleep hygiene

3. Circadian rhythm disorder: Delayed sleep phase syndrome (DSPS), Shift work disorder

4. Narcolepsy: primary and secondary

5. Idiopathic hypersomnia.

6. Medical disorders causing poor sleep at night.

Narcolepsy: is characterized by excessive sleepiness. It may or may not be associated with cataplexy. Cataplexy in simple terms refers to loss of muscle tone. Let me explain with the aid of an example. Let us assume a narcoleptic patient hears a joke. He starts laughing and suddenly experiences loss of muscle tone and finds himself on the ground. This sudden loss of muscle tone is referred to as cataplexy. Another example of cataplexy is a runner who collapses when the starter gun goes off. Narcolepsy is usually accompanied with sleep paralysis and vivid hallucinations which are reported either at onset of sleep or when the patient is about to wake up (that is around sleep-wake transitions). A point to note is that if the patient has cataplexy then the diagnosis of narcolepsy is easy to make. It is narcolepsy without cataplexy that is tough to diagnosis. A caveat to remember here is that not “everything” is cataplexy-so weakness in the knees if you have been laughing hard does not constitute cataplexy. Narcolepsy occurs due to the loss of hypocretin neurons in the lateral hypothalamus. So secondary narcolepsy may also occur if these neurons are damaged by a hypothalamic stroke or a hypothalamic tumor or by a infectious/ inflammatory process (limbic encephalitis). The clinical presentation of secondary narcolepsy though is different: example the history is of excessive sleepiness after a stroke or a tumor.

The diagnosis of narcolepsy is made on the basis of an overnight polysomnography (sleep study) which is done to rule out sleep disordered breathing (sleep apnea). One needs to make sure that the patient does not have untreated sleep apnea before the EDS can be attrbuted to narcolepsy. The patient also undergoes a test called multiple sleep latency test (MSLT). During the MSLT the mean sleep latency is calculated. In narcoleptics the mean sleep latency is usually less than 5 minutes and they also have sleep onset REMs (meaning they enter REM sleep as soon as they fal asleep). This is against what is seen in idiopathic hypersomnia which too has a short sleep latency but there is no sleep onset REMs.

The treatment of narcolepsy and idiopathic hypersomnia is virtually identical. The patient is usually prescribed stimulants such as Adderall, modafinil (Provigil) or Nuvigil.

In my next post I shall elaborate on this further.

Nitin Sethi, MD

White matter lesions in the brain: a question and an answer

One of the readers of my blog asked a very interesting question. I am reproducing her question here. My response to it follows. I hope you shall find it helpful.

Personal Regards,

Nitin Sethi, MD

I am 45 now when I was 25 I was diagnosed as have a pituitary adenoma that caused no active symptoms. Over the years my PCP would follow up with MRI’s and visual field tests. An MRI performed in 03 showed some non specific periventricular high signal white matter changes on the left. Recently in Oct 2010 another MRI was repeated for follow up purposes only. This time it showed several tiny areas of subcortical white matter high signal changes are identified in the right parietal region as well. Pituitary was normal. I am 125 lbs, caucasian femal and I have no neurological symptoms, high blood pressure or diabetes an occasional headache that I get is so mild and I usually pass if off for being tired. My question is what can I do (if anything) to stop these changes from occurring. Does calcium have an effect on this, alcohol consumption (8 to 10 per week) or can cognitive games, etc? Thank you for any input. Best Regards D

braindiseases

Dear D, thank you for writing in. You ask a very good question. Like I explained in my post not all white matter lesions represent MS plaques. The majority of these white matter lesions are what we refer to as ischemic small vessel disease. As the name suggests the pathology lies in the small vessels in the brain. Ischemic white matter disease is more commonly seen as we age. Also patients who have vascular risk factors are more likely to show white matter disease. The common modifiable risk factors are: essential hypertension, diabetes mellitus, dyslipidemia (increased total cholesterol, increased low density lipoprotein and triglycerides and decreased high density lipoprotein), smoking, excessive alcohol intake, obesity and sedentary lifestyle. Some people are hypercoagulable and thus are more prone to strokes and heart disease. Patients who suffer from chronic migraines (especially women) also frequently have “excessive” white matter disease. Now the million dollar question is whether this white matter disease is harmful to the brain. Does it affect the patient cognitively? There are indeed studies that show that excessive white matter disease may make the person prone to cognitive problems later on in life. This is called vascular dementia. My advise to you would be this: If you have any of the above vascular risk factors, I would attempt to modify them. Good control of blood pressure is paramount. Earlier a blood pressure of 130/80 or 140/80 was considered acceptable. Nowdays the teaching is “lower the better”. Hence the new guidelines recommend lowering the blood pressure down to 120/70 mm Hg. In the same vein the guidelines with respect to acceptable cholesterol, triglycerides (TG) and low density lipoprotein (LDL) have become more stringent and again the teaching nowdays is “the lower the better”. If you smoke, quit completely as no amount of smoking is good for your heart or the brain. I would advise you to eat a healthy diet rich in vegetables, fruits and nuts. Exercise on a regular basis (cardiovascular exercise such as jogging or brisk walking has been found to be the most beneficial). I usually recommend my patients to take 1-2 tablets of a good multivitamin per day (one that has all the B group of vitamins). Studies have shown that vitamin B12 plays an important role in cognition and so I usually recommend it to most of my elderly patients especially those who are vegetarians and have a marginal diet. I find my patients frequently deficient in Vitamin D (vitamin D is made in the skin from sunlight and so caucasians living in the temperate areas are frequently vitamin D deficient) and so I supplement it. The amount of vitamin D needed on a daily basis varies according to your sex and age and you should consult your primary care physician to determine how much you should take. I usually give my patients around 400 international units of vitamin D per day. I am a big believer in cognitive games (the fancy word for this now is Neurobics). You can read more about these in my neurobic post here or on my website http://braindiseases.info. I hope I have addressed your concerns adequately. Personal Regards, Nitin Sethi, MD

Not all tremors represent Parkinson’s disease

Patients frequently come to see me for evaluation of their tremor.  Invariably the history is that the tremor was first brought to their attention by a close friend or a family member. The patient is worried that he/she has Parkinson’s disease and hence seek a neurologist’ s attention. Rarely are they bothered by the tremor per-se. By that I mean the tremor is usually not disabling and does not impair their quality of life at least initially. So do all tremors represent Parkinson’s disease? Are there any benign tremors? Which tremors warrant medical attention? These are some of the issues I plan to dwell on in this blog post. I hope some of my readers shall find the information useful.

So what exactly is a tremor. Well neurologically a tremor is characterized by rhythmic oscillatory and involuntary movement across a joint. I used the work involuntary because tremors at times can be voluntary. Voluntary tremor is usually psychogenic (meaning it has a psychological basis to it). We shall not discuss psychogenic/voluntary tremors in this post though. Suffice to say that a doctor shall be able to identify psychogenic tremor based on the history and examination findings alone.

So what do I look for when a patient with tremor comes to me seeking an explanation. Well the age of the patient is the first clue to the etiology of the tremor. Idiopathic Parkinson’s disease usually starts off in the sixth to seventh decade of life. Familial Parkinson’s disease can start at a younger age but usually the tremor is not so prominent nor is it the initial manifestation. There can be many causes of tremor in the “young”.  Various medical conditions some more common such as hyperthyroidism, hepatic and renal diseases and some more exotic such as Wilson’s disease (due to a problem with copper metabolism in the body)come to mind.  At times the answer is more innocuous and the tremor is either due to stress or excessive intake of coffee and other caffeine containing drinks. In that case all that is needed is reassurance. One other disease that needs to be kept in mind is multiple sclerosis though usually more findings are documented in exam (meaning that the tremor is not see in isolation). One should never forget to ask patients about the use of prescription, over the counter and illicit drugs. Many drugs such as sodium valproate (commonly used to treat seizures and at times bipolar disorder), bronchodilators (drugs used to treat asthma, reactive airway disease and chronic obstructive airway disease) cause a coarse postural and kinetic tremor as a side-effect. Once the drug is stopped the tremor abates.

Another common entity frequently confused with Parkinson’s disease is what is called essential tremor or also sometimes referred to as benign essential tremor. Patients who have essential tremor are usually in the same age group as patients with idiopathic Parkinson’s disease and hence the confusion and concern arises. Essential tremor has the following characteristics: it is usually a postural tremor (meaning that the tremor is most prominent when the hands are kept out and maintained at a posture such as having them stretched out in front of you. Remember the classical tremor of Parkinson’s disease is a resting tremor. Meaning the tremor is most prominent when the hands are at rest like for example resting on the patient’s lap and the patient’s attention is diverted). Essential tremor is a faster and finer tremor as compared to the tremor of Parkinson’s disease which is a slower (2-5 Hz) and of higher amplitude. A point to note here is that tremors are frequently classified based on their frequency, amplitude and position (rest Vs postural Vs kinetic).  Patients who have essential tremor frequently in addition to the hand tremor also may have a head tremor (the head shakes either from side to side [no-no tremor] or up and down [yes-yes tremor]). They may also have a tremor in their speech (voice tremor). On further questioning some of them may admit to having the tremor run in their family (meaning their father and grandfather also had a similar tremor). They may have also noted that when they drink alcohol the tremor becomes less prominent.  Infact some patients start drinking excessively for this very reason! Essential tremor usually progresses very very slowly (if at all) and may never become problematic and disabling in the patient’s lifetime.  Hence it does not need to be treated unless it is socially disabling (“Doctor Sethi I cannot drink a glass of wine without spilling it over my dress!” “Dr Sethi  I am so embrassed when my hands shake in a business meeting!”). Essential tremor is not accompanied by the other signs and symptoms which accompany Parkinson’s disease such as gait problems, freezing, stiffness, rigidity and mask like facies.

So not all tremors represent Parkinson’s disease. A quick visit to your “local” neurologist shall give you an answer to what kind of tremor you have.

When a headache is a pain! About primary and secondary headaches

When a headache is a pain! About primary and secondary headaches

Nitin K. Sethi, MD

Assistant Professor of Neurology

New York-Presbyterian Hospital

Weill Cornell Medical Center

New York, NY 10065

 

 

Headaches are a very common reason that patients consult a neurologist like me.  The intensity of the headache, its character and duration are some of the factors which determine if and when patients seek medical attention. So in this post I shall go over the different types of headaches and list their main differentiating features.

Broadly speaking we can divide headaches into primary and secondary headaches. Primary headaches are those headaches for which there is no structural/ secondary cause.  For example a migraine headache is an example of a primary headache. The migraine may be severe and frequently disabling but if you scan (CT or MRI) the patient’s brain no underlying structural lesion like a tumor is found. Secondary headaches as the name implies are secondary to a another cause. For example headache due to a large brain tumor or headache due to an infection (meningitis) represent secondary headaches.

Types of primary headaches:

1)      Migraine: common migraine and classical migraine

2)      Tension type headache

3)      Cluster headache

Types of secondary headaches:

1)      Headache secondary to a brain tumor or other masses (space occupying lesions) in the brain

2)      Headache secondary to an infectious and inflammatory process in the brain (example headache associated with meningitis)

Headaches can be a cause of concern and distress. Patients frequently worry that may have a brain tumor. So let us go over some of the signs and symptoms which suggest that the headache is due to a secondary cause . These are the signs and symptoms which should make you seek urgent medical attention:

1. Sudden onset of severe headache. When asked patients rate their headache as the “worse headache of their lives”. I shall be concerned if I encounter such as patient in the ER, more so if the patient tells me that they have never had a  headache in their life before. When accompanied with other signs such as nuchal (neck) rigidity and depressed sensorium (level of alertness), the question of subarachnoid hemorrhage (SAH) comes to mind. A common cause of non-traumatic SAH is the rupture of an aneurysm or arteriovenous malformation (AVH) in the brain. SAH is associated with high morbidity and mortality especially if the patient presents to medical attention late.

Caveat: Not all “worse headaches of my life” are due to SAH due to rupture of an intracranial aneurysm. Many times (especially if there is a past history of migraine headaches) these patients are suffering from a particularly debilitating/ severe attack of migraine. Thunderclap/ explosive headaches have also been reported at the time of coitus. They are referred to as post coital or orgasmic headache.

1. Headaches in extreme of ages:  headaches which occur in the extreme of ages (such as in a young child or after middle age especially if there is no past history of headaches) deserve a more closer look. Signs such as neck stiffness or depressed level of sensorium may be masked or difficult to elicit in these age groups. As a neurologist my threshold of investigating these patients with tests such as MRI of the brain and more invasive tests such as spinal tap (lumbar puncture) is lower.

Caveat: small children frequently cannot express headache (meaning they cannot tell you that they are bothered by headache).  Primary headaches such as migraine may be missed in children as a result. The child may be agitated and parents may think he is acting up. So a high index of suspicion has to maintained by the physician to timely identify migraines in small children. Also it is well known that migraine is not “typical” in the pediatric age group. Various migraine variants have been identified in children such as abdominal migraine (the child complains of episodic abdominal pain), cyclical vomiting and so forth.

1. Onset of headache in middle age (especially if there is no prior history of headaches): when a middle aged patient comes to me and says he is bothered by headaches for the past 3-4 months, never had headaches when he was in his teens, I pay close attention to him. A thorough neurological examination shall frequently tell me if there is anything “brewing” inside the brain aka does he have a mass lesion/ tumor? As a neurologist I have several tools to help me in this endeavor. I can look for signs of asymmetry: weakness/ numbness on one side of the body, problems with coordination on one side of the body, is the gait steady, are the reflexes symmetrical and so forth. I can further look into his eyes with an ophthalmoscope to see if there is increased pressure inside the brain (remember the eyes are the window into the brain).  Based on my exam, I may or may not order a MRI scan or CT scan to confirm my suspicion.
2. Headaches associated with fever: are always a cause of concern. Various disease processes such as meningitis (bacterial, viral or fungal), brain abscesses and so forth come into the differential. Patients are admitted into the hospital and further management depends upon the underlying etiology.
3. Recent onset of headache in an immunocompromised patient: recent onset of headache in a patient who is immunocompromised (example a HIV positive patient or a patient who is receiving chemotherapy for cancer) always warrant a thorough work-up. Such patients are frequently found to have a secondary cause for their headaches. So again my threshold for imaging such patients is low.  My threshold for doing a spinal tap in these patients is also low (provided I am confident that the pressure in the brain is normal).
4. Headache/ temporal pain  in a patient past 65: temporal arteritis (Giant cell arteritis) is a disease entity which is seen in the elderly and is due to inflammation of the temporal arteries. Patients may not complain of headache per-se. When you examine them you find they have tenderness over the temporal arteries and the artery may feel beaded and thickened.  It is imperative that temporal arteritis be identified in a timely fashion and treated otherwise the patient may suffer loss of vision.

In the next post I shall talk about the primary headaches.