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Neurological examination
Examination, history, and pattern recognition.
A careful neurological history and examination is somewhat daunting and is often skipped, purportedly because of time constraints. In practice, pattern recognition allows the very rapid identification of the majority of neurological problems without a great deal of detailed examination – one can then focus in on one or two aspects of history and exam to tighten up the diagnosis. If you get stumped, however, set aside time away from the middle of a busy clinic or ward round, and come back and do things properly – what seemed very puzzling often becomes embarrassingly clear!
Some signs don’t ‘have’ to be present. Early after a stroke (a classic upper motor neurone lesion) at least 25% of individuals may not be hyper-reflexic. Similarly, not all individuals with lower motor neurone lesions are hypotonic. Once a pattern is recognised, finding one or more physical signs that disagree may provide important clues to an alternative (correct) diagnosis.
- Careful quantification of motor and sensory dysfunction allows one to more accurately assess progression or improvement.
- Receptive language problems are cortical. Fits accompanying a stroke also usually imply cortical pathology.
- A lower motor neurone VIIth with a VI on the same side implies a pontine lesion.
- Spinal cord lesions often have a sensory level and bladder involvement.
There are a few useful nerve root functions that can be helpful with localisation
Reflexes
Tapping reflexes is a quintessential medical skill which the public strongly associate with thorough examination.1 It is somewhat unfortunate that not all clinicians are comfortable with it.
Which hammer
Use a decent hammer. The easiest to use are those with a long plastic handle and a relatively heavy head. (The Queen Square hammer.) Check that the handle and head are firmly attached – it’s a bit embarrassing if the head flies off in mid stroke. Other hammers which are often found lying around the ward (hint: nobody wants them!) are the tomahawk (or Taylor) hammer and the Babinski, which is like a Queen Square one with a rigid metal handle. Useable, but tricky if you haven’t practiced with them, and there is some evidence that the Taylor hammer may be unable to generate adequate force in some hyporeflexic patients.2
Eliciting reflexes
Settle the patient comfortably, preferably lying down. Do not ask the patient to relax. Seeing a giant figure looming over you with hammer in hand when you are feeling sick requires Zen-like equanimity in order to voluntarily ‘relax’. Rather distract with conversation – easy questions about where a patient stays and who else is in the family work best.
For the arms, place the finger of one hand over the tendon, and then let the hammer fall onto your finger, and follow through. Don’t jerk to a stop just before contact – tentatively flicking at tendons doesn’t work. For larger tendons, such as those in the legs, hitting them directly without an intervening finger is fine. For the biceps reflex, try to position the elbow as close to 90 degrees as possible3.
Compare the two sides, and if not sure, repeat. If you still aren’t sure, you aren’t going to be, so move on. Checking a single pair of reflexes again and again is seldom helpful.
Difficult to elicit reflexes
Reinforcement ( Jendrassik’s manoeuvre) may help – for arm reflexs ask the patient to clench the jaw, for legs, either jaw clench or squeeze hands together.
The plantar response (Babinski) is useful, although technically a cutaneious reflex rather than a deep tendon reflex. Don’t press too hard, and move along the lateral side of the sole, then across the ball of the foot without touching the toes themselves. It is the first flicker that counts, not the subsequent withdrawal response. If one toe flexes promptly and fully, and the other also flexes, but less enthusiastically, this is significant.
Interpreting the reflexes
Look for patterns rather than putting all your emphasis on a single reflex. Observe what is actually there, rather than hoping to get what you expect – not all patients with new strokes are hyper-reflexic on the side of the stroke. Lack of symmetry between the two sides is sometimes more important than making the call on which side is increased or decreased.
Document what you found specifically – don’t just say reflexes are equal, but write ‘R biceps ++’ or ‘L ankle jerk – ‘.
Unexpected hypotonia and hyporeflexia
One of the fascinating aspects of both neurology and medical pedagogy is the finding of reduced tone and reflexes in patients with strokes and spinal cored lesions, and the complete lack of a theory of why that might be amongst many junior clinicians. It seems to be a gap in medical education – if you don’t acknowledge it exists, you don’t have to explain it. The reason is perhaps that explanations are tenuous and difficult to find. One of the more tenable explanations concerns input from the supplmentary motor cortex, and the influence of spinal inhibitory interneurones which probably modulate planned motor activity. The bottom line: reduced inhibition of inhibitory interneurones may lead to reduced tone and reflexes in the acute state.4 Even if the explanation becomes clearer (or completely different!) over time, acknowledging that not all stroke patients are hyper-reflexic is a good start.
Lees AJ, Hurwitz B. Testing the reflexes. BMJ 2019;366:l4830 doi: 10.1136/bmj.l4830 (Published 14 August 2019 ↩
Marshall GL, Little JW. Deep tendon reflexes: a study of quantitative methods. J Spinal Cord Med. 2002;25:94–99 ↩
Isik K, Nilufer B, Mehment B. The effect of elbow position on biceps tendon reflex. Neurology India 2004;52(3):350–352 ↩
Florman Jeffrey, Duffau Hugues, Rughani Anand.Lower Motor Neuron Findings after Upper Motor Neuron Injury: Insights from Postoperative Supplementary Motor Area Syndrome Frontiers in Human Neuroscience 2013,7 URL=https://www.frontiersin.org/articles/10.3389/fnhum.2013.00085 DOI=10.3389/fnhum.2013.00085 ↩