Cerebral aneurysms are scary things. It is alarming enough that they exist, but it is more spine-chilling that they enlarge with time. The most infamous aneurysm arises from the posterior communicating artery, the so-called PCOM aneurysm. And it signifies its sinister intent when it gradually enlarges and compresses its vascular neighbour, the third cranial nerve, otherwise known as the oculomotor nerve. A dysfunctional third nerve manifests with a droopy eyelid (ptosis) and double vision (diplopia). The reason for the double vision becomes obvious when the neurologist examines the eyes; one eyeball is out of kilter and is deviated downwards and outwards; it is indeed down and out! The pupil is also very widely dilated (mydriasis). These are among the most worryingred flags in medicine, and a very loud call to arms. Cerebral aneurysms however often wave no flags, red or otherwise. Indeed the most malevolent of them will expand quietly until they reach horrendous proportions, and then, without much ado, just rupture. They are therefore veritable time bombs…just waiting to go off.
Cerebral aneurysm however do not need to reach large proportions to rupture; some just rupture when they feel like. Aneurysms under 7mm in diameter however are less prone to rupture. A rupturing aneurysm presents with very startling symptoms. The most ominous is a sudden onset thunderclap headache (TCH), subjects reporting feeling as if they have been hit on the back of the head with a baseball or cricket bat. It is not quite known what non-sporting patients experience-for some reason they never get aneurysms in neurology textbooks! More universally appropriate, a ruptured aneurysm may manifest as sudden loss of consciousness. Both symptoms result from leakage of blood into the cerebrospinal fluid (CSF) space, a condition known as a subarachnoid haemorrhage (SAH).
You may breath a small sigh of relief here because the vast majority of people with thunderclap headaches do not have subarachnoid haemorrhage. Unfortunately, every person who presents with a thunderclap headache must be investigated- to exclude (hopefully), or confirm (ruefully), this catastrophic emergency. The first test is a CT head scan which identifies most head bleeds. The relief of a normal scan is however short-lived because some bleeds do not show on the CT. The definitive test to prove the presence or absence of a bleed is less high tech, but more invasive: the humble spinal tap or lumbar puncture (LP). This must however wait for least 12 hours after the onset of headache or blackout. This is the time it takes for the haemoglobin released by the red blood cells to be broken down into bilirubin and oxyhaemoglobin. These breakdown productsare readily identified in the biochemistry lab, and they also impart on the spinal fluid a yellow tinge called xanthochromia. The test may be positive up to 2 weeks after the bleed, but the sensitivity declines after this time. A positive xanthochromia test is startling and sets off an aggressive manhunt for an aneurysm-the culprit in most cases.
Many people with cerebral aneurysms have a family history of these, or of subarachnoid haemorrhage. Some others may have connective tissue diseases such as Ehler’s Danlos syndrome (EDS), adult polycystic kidney disease (APCKD), or the rare Loeys-Dietz syndrome. This family history is a window of opportunity to screen family members for aneurysms. The screening is usually carried out with a CT angiogram (CTA) or MR angiogram (MRA). People are often not born with aneurysms, but tend to develop them after the age of 20 years. Aneurysm surveillance therefore starts shortly after this age, and many experts advocate repeating the screening test every 5-7 years until the age of 70-80 years.
How are aneurysms treated? This will be the subject of a future blog post so watch this space!
This is a follow-up to my previous blog post, So what is remarkable about neurology anyway? That post reviewed the challenging tasks neurologists face everyday. How do they go about it? How do they evaluate their patients with suspected neurological disorders?
For the uninitiated, the process of the neurological assessment must seem like an outlandish ritual. Unlike cardiologists who approach patients with the familiar stethoscope, neurologists come armed to the hilt with an arsenal of threatening equipment. Patients are often bewildered, and occasionally irritated, with the neurological exam. Admitted, they sometimes, they sometimes emerge from the assessment feeling battered and bruised-all for a good cause of course!
So what are these bizarre deeds that marks the neurological consultation?
1. Neurologists welcome you with an overly firm handshake
The handshake is a valuable neurological tool. It tells the neurologist right from the beginning if there is any weakness or if there is a form of muscle stiffness called myotonia. Therefore avoid the neurologist’s handshake if you suffer with arthritis or other painful hand conditions.
2. Neurologists make you do the catwalk
The way you walk, the gait, may show the neurologist a variety of clues or signs. There are a variety of abnormal gaits that often point to a diagnosis even before the consultation actually begins. Examples include the shuffling gait in Parkinson’s disease, the hemiparetic gait in Stroke, and the waddling gait in diseases that give rise to hip girdle weakness. More embarrassing for some patients is that the neurologist may actually ask them to do a catwalk, all for the sake of making a diagnosis you must understand!
Other bizarre associated tests are walking an imaginary tightrope, standing on one leg, standing on tip toes and then on the heels, and marching in one spot with eyes shut
3. Neurologists stare intently at you
The face often give the neurologist the clue to many diagnoses. Conditions such as Bell’s palsy and Stroke are evident from the face as are Parkinson’s disease, myotonic dystrophy and facio-scapulo-humeral muscular dystrophy (FSHD). There’s no need to blush therefore when the intent gaze seems to go on endlessly.
4. Neurologists come up very close- to peer into your soul
If the eyes are the windows to the soul, then neurologists are second only to ophthalmologists in recognising this nebulous entity. The back of the eye, or retina, holds a variety of valuable clues for many neurological diseases. The neurologist typically looks for signs of increased pressure in the head and this may occur with brain tumours, meningitis, encephalitis, This may also occur without any obvious cause in a condition called idiopathic intracranial hypertension (IIH). Other eye signssuch as cataracts and pigmented retina seen with disorders for example mitochondrial diseases.
To peer into the soul, the neurologist may come very uncomfortably close, (hoping the aftershave isn’t too strong and that the morning deodorant has lasted till then). Don’t hold your breath however, as this gazing into the soul may take longer than you anticipate.
5. Neurologists ask you to roll your eyes-in all sorts of directions
Abnormal eye movements are key pointers to many neurological disorders. There are six muscles that move each eyeball, and these are under the control of three pairs of cranial nerves-the oculomotor, the trochlear, and the abducens nerves. These nerves in turn are coordinated by complex nerve cell bodies or nuclei in the brain stem.The eyelids and pupils are also muscles under control of nerves.
These cranial nuclei coordinate a symphony of unparalleled and unimaginable complexity. This allows us to focus on moving objects without any hinderance. Things may go wrong with this symphony, and this typically results in double vision (diplopia) and droopy eyelids (ptosis). Diseases that cause these symptoms include brain aneurysms,myasthenia gravis (MG), and brainstem stroke. Some diseases may cause the eyeballs to move in uncontrollable and chaotic ways called nystagmus, oscillopsia, and opsoclonus(neurologists love these names!)
Don’t be shocked therefore when your neurologist asks you to look up, look down, look to the right and left; to follow this or the other hand; to look at this fist then at these fingers…. It’s all a helpful game-honest!
6. Neurologists ask you to pretend to brush your teeth
Your neurologist may request you to brush your teeth or hair with an imaginary brush, or ask you to do victory sign or the thumbs-up sign (never thumbs-down mind you). Almost verging on the comedic, this is a serious test because these simple tasks are impaired in many diseases. The difficulty in performing tasks one has previously been proficient at is called dyspraxia, or apraxia if the ability is completely lost. Without any weakness or numbness, people with dyspraxia are unable to use common tools and equipment, reporting that they have no idea how to manipulate them. This could be seen in some forms of stroke and some dementias. Do decline however if she asks you to mimic the great mime Marcel Marceau.
7. Neurologists ask you to wiggle your tongue and poke it out
The tongue is a very important muscle and holds countless clues for the neurologist. It is innervated by the last of the 12 cranial nerves, the hypoglossal nerve. which may be paralysed by a very localised stroke and this is often in the context of a condition called cervical artery dissection. This is a tear in one of the big arteries in the neck which take blood to the brain. The tear may arise from trivial neck movements and manipulations such as look up for a long time or staying too long on the hairdressers couch. A clot then forms at the site of the tear, and this then migrates to block a smaller blood vessel supplying the brainstem where the hypoglossal nerve sets off from…phew! Anyway, when this kind of stroke occurs, the tongue deviates to the the weaker side when it is poked out.
The more general weakness of the tongue is seen in conditions such as motor neurone disease (MND),in which the tongue also quivers at rest-something neurologists call fasciculations. The cheeky neurologist (pun intended) will ask you to push against her finger through your cheek to test its full strength.
Another problem that may affect the tongue is myotonia, a condition in which he tongue and other muscles are stiff and relax very slowly after they are activated. To test this, your neurologist may actually tap on your tongue, and then watches in fascination as it stiffens and then relaxes very slowly. Strong but slow moving tongues may be seen in Parkinson’s disease (PD). So, when next your neurologist says ‘open up’, he really means business.
8. Neurologists flex their muscles against yours
OK, she will not literally wrestle you to the ground but it may appear so at times. Pushing against your head, pressing down against your elbows, leaning hard against your leg-she will do everything to show she is stronger than you. Only if she fails will she score your power as grade 5/5-the best you can get. If you do not score full marks however you place the neurologist in a bit of a quagmire; a score between 0-5 is not always easy to allocate, and the obsessive neurologist may get in a bind and may give you marks such as 3+ or 4-. Just for fun let her win, and see her consternation!
9. Neurologists hit you with a hammer-in all sorts of places
The reflex hammer is perhaps the most well-recognised tool of the neurologist. These hammers come in all shapes and sizes, and some are really quite scary. People expect to have their knees tapped and look forward to what they have seen many times on TV-the leg kicking out. Most patients find this amusing. They are however often surprised when the neurologist proceeds to use the hammer on their jaw, elbow, wrist and ankles. The then often bristle at having the soles of their feet stroked by the end of the hammer’s handle, a sharp uncomfortable end it is. All the hammer does is to stretch the tendons of muscles, and this elicits a reflex that causes the muscle to contract or tighten up. This response may be exaggerated (hypereflexia) if there is any problem in the central nervous system. Conversely the reflex response may be diminished (hyporeflexia) with problems of the peripheral nervous system. Stroking the foot is called the Babinski response and gives a similar form of information to the neurologist. But beware the neurologist who then proceeds to stroke the side of your foot or squeeze your shins, all in an effort to get the same information-it is really an unnecessary and uncomfortable duplication of tests.
10. Neurologists prick and prod you with a sharp pin
Now this must take the cake, and quite rightly often comes at the end of the neurological examination. As threatening as this tests appears, this is probably the neurologist at his most acute. Using a sterile pin, the neurologist asks you to respond ‘yes’ if the sensation you perceive is sharp, and ‘no’ if it is dull. He then carefully proceeds to map out areas of reduced sensation or feeling, frowning as he struggles to keep track of your responses in his mind. He tries to establish if you have a glove and stocking pattern of sensory loss seen in peripheral neuropathy (nerve end damage). It may also be a dermatomal pattern seen with radiculopathy (trapped nerve in the spine). Unfortunately for the neurologist however many patients do not understand the rules of the game and give all sorts of unimaginable responses; not surprising when one is under the threat of a sharp pointy object!
These are but a few of the bizarre doings of neurologists. Seeing a neurologist soon? Be prepared-you have been warned!
PS. Images used in this blog post are for illustration purposes only and do not necessary depict the actual equipment used by neurologists. The examination steps described are however a good reflection of actual neurological practice.