Neurology. Charles H. Clarke

III: Oculomotor Palsy (complete)

      A complete IIIrd causes:

       Ptosis – upper lid drops and covers eye

       Large pupil unreactive to light (contralateral pupil constricts normally)

       An eye (lift upper lid) that’s ‘Down & Out’.

      A partial IIIrd spares parasympathetic fibres (these fibres run beneath the nerve ‐ separate blood supply). Pupil: normal. Ptosis: incomplete.

       Internuclear Ophthalmoplegia (INO)

      INO = damage to brainstem medial longitudinal fasciculus.

       Disconjugate horizontal eye movements – eyes move at different velocities. Look at the patient’s forehead: otherwise you fixate on one eye and miss what’s happening to the other.

       Incomplete ADDuction of one eye.

       Coarse jerk nystagmus on lateral gaze in the other eye (on ABDuction).

      INO is left‐sided when there is failure of left ADDuction (looking right).

       IV: Trochlear Palsy

      A rarity, compared with others:

       Double vision on looking down, twisted images, a.k.a. torsional diplopia

       Head tilt: away from side of superior oblique weakness

       No obvious squint.

      When diplopia does not fit one of the patterns above, Formal Rules help.

      1 False image: usually the less distinct and more peripheral

      2 Diplopia: occurs in positions dependent upon contraction of a weak muscle

      3 False image: is projected in direction of pull of the weak muscle

      4 Image separation: increases in direction of pull of the weak muscle.

      Dificulties: these include myasthenia, where diplopia varies; also blurring/false‐framing is easily accomplished, sometimes deliberately, by converging too closely. Diplopia is normal at extremes of gaze.

       V: Trigeminal, Sensory and Motor

      Most with sensory loss within one or more trigeminal branches complain of symptoms in a defined zone (see Cranial Nerves Figure 13.3). Most of us have had temporary V₃ loss, at the dentist.

      Motor V lesions are unusual. Look at the centre line of incisor teeth, upper and lower. See if the lower incisors remain central or move laterally as the jaw opens against slight resistance. Then assess the jaw jerk.

       VII: Facial

      A complete LMN facial palsy affects all facial muscles on one side. Upper motor neurone (UMN) weakness affects the lower face; this spares blinking and forehead wrinkling. In early UMN facial weakness a hint of slowing of a blink, or grimace is all that may be seen, sometimes with dissociation between voluntary and involuntary movement.

      Make suggestions:

       Frontalis: ‘look upwards’ produces furrowing of the brow.

       Orbicularis oculi: ‘screw up your eyes tightly’

       Alae nasae: ‘wrinkle your nose’

       Orbicularis oris: ‘now try to whistle gently’

       Risorius: ‘… and now please show me your teeth’

       Platysma: ‘tension the skin of your neck’.

      Involuntary movements (e.g. myokymia, fasciculation and slight hemifacial spasm): illuminate the face well. Finally, as a practical point, gradual emergence of patchy facial weakness is distinctly unusual in Bell’s palsy.

       VIII: Auditory

      Testing is unnecessary when there is no problem. With some hearing loss, note distance at which a whisper is heard. Rinne & Weber tests are now felt to be of doubtful value.

My approach: occlude gently both external auditory meati with the tips of each index finger. Rustle with each middle finger the skin/hair over the mastoid – a measure of bone conduction. If there is marked difference between each side, sensorineural loss is usually present. Any suspicion of a CPA lesion: MRI and audiometry.

       VIII: Vestibular

      Dizziness, vertigo and nystagmus: Chapter 15. Gait & stance, Romberg & Unterberger tests. Common error: over‐diagnosis of nystagmus. A few beats at extremes of lateral gaze is normal. Nystagmus must usually be sustained, within binocular gaze to be pathological.

       IX and X: Glossopharyngeal and Vagus

      Take both together. Observe uvula & fauces saying ‘Aaah’. Look for saliva pooling, food, palate/uvula deviation.

       Voice sounds ‘wet’ in early bulbar weakness (Chapter 13)

       Listen to a cough

       Watch patient begin to drink, if safe – spluttering, pooling.

      An isolated IXth – almost impossible to identify – causes impaired unilateral pharynx sensation.

       XI: Accessory

      Trapezii and sternomastoids: scapula winging, weak shoulder shrugging and head turning,

       XII: Hypoglossal

      Tongue: wasting and deviation to weak side when protruded. Speed and amplitude diminished in pyramidal lesions and Parkinson’s. Fibrillation: diagnose fibrillation only when tongue rests within mouth; twitching occurs in normal people when protruded.

      Gait and Movement Disorders

      Assess gait:

       Normal, symmetrical, without limp

       Spastic – narrow‐based, stiff, toe‐scuffing

       Hemiparetic

       Extrapyramidal – shuffling, festinant (hurrying), with poor arm swinging, slow

       Apraxic – with gait ignition failure, with walking difficulty but preserved ability to move legs rapidly on a bed or seated

       Ataxic

       High stepping, foot drop, myopathic, antalgic, neuropathic

       Otherwise unusual – dystonia, chorea or myoclonus, or apparently theatrical.

      Do not miss subtleties – early chorea, a little dystonia. A video on a phone is helpful.

      Motor System

      Techniques are important.

       Posture of Outstretched Upper Limbs

       Ask the patient