The role of the Speech and Language Therapist in Awake Neurosurgery

This week, I attended a talk given by Professor Peter Marien from the University of Vrije, Brussels. He is a neurolinguist, and was talking about standardising a procedure for when performing awake neurosurgery involving the language areas of the brain.

Awake neurosurgery has been going on since the late 19th century, originally during the treatment of epilepsy. Since the 1970s, a neurosurgeons have been developing a procedure which involves waking the patient up during tumour resection operations in order to test which parts of their brain are involved in language. As everyone's brain is different, it is impossible to fully map which parts are involved in language (fMRI has been shown to not give a full picture). To gain a more accurate impression, the brain is stimulated using an electrode in different parts as the person talks, and each section is labelled (either with something that looks like a tiny post-it note(!) or through computer software imposing a grid on the microscope view). The areas that, when stimulated, affect language are then avoided as far as possible during the resection. As a result,  damage to linguistic areas is reduced.

Until recently these tests have been chosen, devised and carried out by the surgeon or anaesthetists present. As a result, the tests are not necessarily comprehensive - for example, just asking the patient to count to 10 and name some pictures, which does not represent all the complex language operations we carry out each day such as reading, understanding, pragmatics - and those interpreting the results are not specialists in doing so - the example Prof. Marien gave was of an anaesthetist who carried out the assessment accepting "donkey" as a label for "horse" - hello semantic substitution!

As a result, Prof. Marien is part of a team involving neuro-linguists and SLTs, focussing on championing their involvement in these operations. SLTs understand what assessments are appropriate in order to fully test receptive and expressive language: for example involving conversation, reading, understanding and expression, and identify symptoms of vocal interruption, dysarthria or aphasia more accurately. These assessments need to be carried out pre-operatively in order to discern a person's abilities (make sure they know all the words in the assessment etc) and then in theatre. 


At the moment no "gold standard" exists for  awake neurosurgery, and there is no obligation for SLTs to be involved. But with a shorter recovery period (patients are usually discharged within 5 days of the op) and reduced rehab costs, as well as better chance of language preservation it seems so important to create this, and for it to involve SLTs (or neuro-linguists).

I still have some more questions that I need to research: for example, although Prof. Marien stated each of these areas are generally distinct, presumably it is not always to preserve all of them. How do they prioritise which is saved, for example (to put it crudely) do they value receptive language over dysarthria? Also, how do you ensure that every function is tested in every brain area - presumably each section of assessment must be long enough for the electrode to be placed in every position otherwise something might be missed, but how can this be organised to avoid fatigue in the patient? 

This seems like a fascinating area to be involved in, and Prof Marien was an excellent speaker (the graphic videos helped - for a taster check out this video at 1min45secs of someone playing a violin during an operation to reduce tremors in the arm!).