Multiple Sclerosis–making the diagnosis

I still continue to get many questions from the readers of my blog regarding multiple sclerosis (MS). A significant majority of them write to me because they are concerned they may have MS either because of white matter lesions found on a MRI scan of the brain or because they are plagued by various non-specific signs and symptoms. Though I have written about this before, I thought this shall be a good time to go over how the diagnosis of MS is made. What are the symptoms that raise the suspicion for MS, what are the clinical signs on examination that suggest MS and finally what are the tests that may help to confirm the diagnosis.

Before I dwell deeper into this topic, please remember: THE DIAGNOSIS OF MS IS A CLINICAL ONE. Meaning that it can be made on the basis of a history and clinical examination itself. No tests are needed in such a situation to confirm the diagnosis.  Of course as it is often in medicine–it is always not that easy.

So let us begin—

Clinical history: Are there any points in the clinical history of the patient that suggest the diagnosis of MS? Patients with MS may give a history of neurological symptoms and signs (remember signs are elicted on clinical examination-meaning when the doctor examines you) that wax and wane (relapsing and remitting MS). A patient may present with acute loss of vision in one eye along with pain in the eye  (I am talking about optic neuritis). As the doctor dwells deeper into the history, the patient volunteers that a couple of years ago he had a similar problem in the other eye which had resolved on its own and he had not been investigated further. Hmmm–now we have history of 2 attacks separated in time. As a neurologist this makes me think of MS as a possible diagnosis. The problem with MS though is that it may present with non-specific signs or symptoms or rather it may present with signs and symptoms that localize to different parts of the central nervous system (CNS). By CNS I mean the brain and the spinal cord. So for example patients may present with numbness on weakness on one side of the body (this localizes to the contralateral motor or sensory cortex), problems with the bladder (incontinence–this usually localizes to the spinal cord), problems with balance and coordination (their gait is off and they may have a prominent tremor in their limbs–this localizes to the cerebellum or the brain stem), double vision (this localizes to the cranial nerves which control the movement of the eyes). Virtually any part of the central nervous system can be involved–hence the presentation is at times non-specific. BUT WHAT HELPS US AS DOCTORS IS WHEN WE GET HISTORY WHICH SUGGESTS A DISEASE DISSEMINATED IN SPACE AND IN TIME. Meaning a disease process which is involving different parts of the central nervous system and which has shown evidence of multiple attacks separated by time. REMEMBER MS IS NOT A MONOPHASIC ILLNESS (it relapses and remits!!!)

Clinical examination: So what are the clinical examination findings which make me as a neurologist think of MS in  a patient. There are certain neurological signs which have been said to be pathogonomic of MS (meaning the presence of these signs virtually seals the diagnosis of MS). These include certain eye signs. Bilateral internuclear opthalmoplegia (INO) (who said neurology was easy!!!) is one such sign. This is an eye-sign in which the patient’s eyes do not move as directed by the examiner. One eye fails to adduct (that is move inwards) while the other eye  abducts (moves outwards) but the abducting eye shows a nystagmus (shaky side to side movement). Other eye signs such as an afferent pupillary defect (this is elicted by shining a penlight into the eye) also raise suspicion for MS. What we as neurologists look for though is this–we look for signs that suggest the disease is disseminated in the CNS. REMEMBER WHAT I TOLD YOU ABOUT MS. IT IS A DISEASE WHICH IS DISSEMINATED IN TIME AND SPACE.

Tests: so when a diagnosis of MS cannot be made on the basis of history and examination alone, we as doctors have to fall back on tests to rule in or rule out the diagnosis. No test seals the diagnosis of MS by itself. They just help to add to our certainity. I shall discuss the various tests namely –imaging studies such as MRI scan of the brain and spinal cord., evoked potential studies such as visual evoked potential (VEP), somatosensory evoked potential (SSEP), brain stem auditory evoked potential (BAEP), spinal fluid (CSF) examination in the next post.

 

Nitin Sethi, MD

Is it or is it not multiple sclerosis?

Since my posts on multiple sclerosis are getting many hits from readers, I thought that I would in this post describe how a definitive diagnosis of MS is made.

First and foremost, a definitive diagnosis of MS can be made just clinically without any other imaging studies like MRI or the need for invasive tests like lumbar puncture (spinal tap). How you may ask?

Well if by history you have had two attacks suggestive of MS which are disseminated in time and space, then a definitive diagnosis of MS can be made. Let me explain this in simple language. Lets assume you go to your doctor because you have been having numbness in your right arm. Your doctor examines you and finds that apart from sensory loss in the right arm, you have other examination findings such as you have ataxia (your gait is off and unsteady), you have incoordination and tremor in your right arm, your eyes do not move well and you have what we call internuclear opthalmoplegia. Hmm sorry for all that medical jargon, let me try to make it more simple. What I am trying to say that your examination findings are suggestive of not one but multiple sites of pathology in your brain.

Numbness right arm localizes to the sensory cortex on the left side of your brain.

Ataxia might be due to midline cerebellar problem

Right arm tremor localizes to the right cerebellum (cerebellar pathways are double crossed in the brain)

The eye findings and internuclear opthalmoplegia localizes to the midbrain.

So you have signs that whatever your disease is it is disseminated in space (SPACE AS IN DISSEMINATED IN DIFFERENT  PARTS OF THE BRAIN). Your findings cannot be explained by one single lesion rather by multiple small lesions.

So you have met the first criteria to make a definitive diagnosis of MS-dissemination in space. (OF COURSE DISSEMINATION IN SPACE SHALL ALSO BE CLEARLY SHOWN IF YOU DO A MRI SCAN)

 Now how do we prove you have dissemination in time?  Well that is done by history. Lets assume your doctor now asks you ” Miss Smith have you ever had a problem with your eye before? Did you ever lose vision in one eye?”

Miss Smith: ” Now that you ask doctor Sethi, yes. When I was 18, I had an episode where I had pain in my left eye and lost vision rather abruptly. By the time I saw my doctor, it had started to improve by itself and I did not think much of it.”

Viola!!! here the history is telling you that Miss Smith has in fact had dissemination in time. Likely she had an attack of optic neuritis when she was 18 which had resolved by itself.

So as a doctor examining Miss Smith, I now know that her disease is disseminated in time (she has had attacks in the past) and also in space (from my examination findings I know that she likely has multiple lesions in the brain, only then I can explain all her findings).

I DO NOT NEED ANY ADDITIONAL TESTS TO MAKE A DIAGNOSIS OF MS. SHE HAS HAD 2 ATTACKS DISSEMINATED IN TIME AND SPACE.

Of course as part of her management I would do a MRI study of the brain and some doctors might still do a lumbar puncture. 

 Additional tests like MRI brain, spinal tap and evoked potentials (visual and somatosensory evoked potential) are needed when either of the above 2 is missing. Either Miss Smith has had just one clinical attack or her examination finding are suggestive of one lesion.

Nitin Sethi, MD