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