Clinical assessment of pain

Successfully treating chronic pain is challenging, as patients respond heterogeneously to analgesic treatments. Such variation in response can be attributed to differing underlying pain-generating mechanisms. A novel clinical bedside test that identifies distinct pain phenotypes might help deliver more-effective mechanism-based treatment strategies.

Bilateral facial nerve palsy

Foix-Chavany-Marie (bi-opercular) syndromeIn 1926, Foix, Chavany, and Marie described an acquired syndrome of faciopharyngoglossomasticatory diplegia, caused by bilateral infarction of the anterior operculum (eg, anterior choroidal artery infarction). Clinical features included: facial diplegia, dysarthria, pseudobulbar palsy, cognitive deficits, and seizures. Foix-Chavany-Marie syndrome is also known as the biopercular syndrome (descriptively based on the typical associated lesions affecting the anterior operculum bilaterally) or faciopharyngoglossomasticatory diplegia with automatic voluntary association (descriptively based on the clinical features). Essentially this is a cortico-subcortical type of suprabulbar palsy.

Visually-evoked rooting

The group of reflexes collectively known as "primitive reflexes", reviewed by Schott and Rossor,2 include the grasp, snout, palmomental, and rooting reflexes. They are usually associated with neurodegenerative diseases causing dementia and, as the authors point out, loosely linked to frontal lobe pathology, but their exact physiological and anatomical substrates are poorly understood.
The well known tactile-evoked rooting reflex is the movement of both lips towards the examiner’s finger when stroking the lateral side of the upper lip. However, there has been very little written about the related phenomenon of visually-evoked rooting.

Examine eye movements

As with all aspects of the neurological examination, important clues come from a thorough and appropriate history. In relation to eye movement disorders the patients may be complaining of double vision, in which case they should be asked whether it is constant or intermittent; does it occur, or is it maximal, in certain directions of gaze; what is the relationship of one image with the other; and have they tried covering one eye and did that relieve the symptom? A less frequently reported symptom is oscillopsia, an illusion of movement of stationary objects, when enquiries need to be made whether the movement is horizontal or vertical, and does it become maximally apparent in certain positions of gaze, as for example in downbeat nystagmus when the oscillopsia is maximal on down gaze.