Cranial Nerve Examination Lecture Notes PDF

BDS Year 2 Lecture, 9th December 2020 Examination of the cranial nerves Heinz Jungbluth MD PhD 1 1-3 Department of Paediatric Neurology, Evelina Children’s Hospital, Guy’s and St. Thomas’ NHS Foundation Trust, 2 3 London, UK; Randall Division of Cell and Molecular Biophysics, Muscle Signalling Secti...

BDS Year 2 Lecture, 9th December 2020 Examination of the cranial nerves Heinz Jungbluth MD PhD 1 1-3 Department of Paediatric Neurology, Evelina Children’s Hospital, Guy’s and St. Thomas’ NHS Foundation Trust, 2 3 London, UK; Randall Division of Cell and Molecular Biophysics, Muscle Signalling Section, and Department of Clinical and Basic Neuroscience, IoPPN, King’s College, London, UK Case report A 38-year-old man had a right inferior dental nerve block to allow the replacement of an amalgam restoration in his lower second molar tooth. Over 6 hours he developed a progressive ipsilateral facial weakness and hyperaccusis was noted. He was referred for specialist opinion after returning to the dental practice the following day. Cousin GC Nerve palsy following intra-oral surgery performed with local anaesthesia R Coll Surg Edinb. 2000; 45(5):330-3. Objectives Principles of CN examination Technique of CN examination Recognition of - common CN abnormalities - common syndromes involving multiple CN - systemic disease with CN pathology Quiz ! Principles of cranial nerve pathology supranuclear lesion ? Single CN involvement peripheral lesion ? CNS lesion ? Multiple CN involvement systemic disease ? 1 2 3 4 5 6 7 8 9 12 10 11 Sequence of the CN examination Examination - smell (CN I) - the eyes (CN II,III,IV,VI) - the face (CN V,VII) - hearing and balance (CN VIII) - the mouth (CN V,VII,IX,X,XII) - neck and shoulders (CN XI) Examination of smell Examination of smell CN I - Olfactory nerve CN I – olfactory nerve Bilateral anosmia - trauma, Parkinson’s Disease, COVID-19 Unilateral anosmia - frontal lobe lesion Functional anosmia Examination of the eyes Sequence of the eye examination Inspection Pupillary reactions Visual acuity Visual fields Eye movements Fundoscopy Examination of the eye CN II – Optic nerve CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Direct Consensual Accommodation Visual fields Afferent: CN II Optic Efferent: CN III Oculomotor Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy CN II – Optic nerve Inspection Pupillary reactions Visual acuity Visual fields Fundoscopy Normal fundoscopy findings CN II – Optic nerve Inspection Pupillary r Visual acuity 1 Fundoscopy 2 3 CN II – Optic nerve Inspection Pupillary r Visual acuity 1 Normal Fundoscopy 2 Papilloedema 3 Optic atrophy Examination of eye movements CN III, CN IV, CN VI CN III, CN IV, CN VI HH Examination of eye movments CN III, CN IV, CN VI From Brodal, Neurological Anatomy, 1981 Examination of eye movements CN III, CN IV, CN VI From Brodal, Neurological Anatomy, 1981 ? ? CN III – oculomotor nerve palsy Controls four muscles of eye movement Causes pupillary constriction Controls eyelid elevation by innervating levator palpebrae superioris muscle CN III – oculomotor nerve palsy From Brodal, Neurological Anatomy, 1981 CN III – oculomotor nerve palsy RL SO ? CN IV – trochlear nerve palsy CN IV – trochlear nerve palsy From Brodal, Neurological Anatomy, 1981 ? “Look to the your left” CN VI – abducens nerve palsy X “Look to the your left” CN VI – abducens nerve palsy From Brodal, Neurological Anatomy, 1981 Double vision rules Maximal in direction of gaze of affected muscle False image - outer image - arises in the affected eye Single palsies of CN III, IV and VI Medical - e.g. diabetes, atherosclerosis Surgical - e.g. tumor, aneurysm, trauma ? External ophthalmoplegia Examination of the face CN V and CN VII CN V – trigeminal nerve Sensory function Motor function CN V – trigeminal nerve Sensory function Motor function CN V – trigeminal nerve Afferent: CN V Trigeminal Efferent: CN VII Facial Corneal reflex CN V – trigeminal nerve damage Frey’s syndrome (Image NEJM) (auriculotemporal branch of CN V near parotid gland) CN V – inf. alveolar nerve damage Inferior Alveolar Nerve damage (mandibular division of trigeminal nerve) Inferior Alveolar Nerve, (a branch of the mandibular division of the trigeminal). Common with implants and root treatments -Third molar surgery related inferior alveolar nerve injury is reported to occur in up to 3.6 % of cases permanently and 8% of cases temporarily. http://trigeminalnerve.org.uk/patient-resources/what-are-tn-injuries/ CN VII – facial nerve Motor function Sensory function CN VII – Facial nerve “Scrunch your eyes closed” “Wrinkle up your forehead” “Blow out your cheeks” “Smile” CN VII – Facial nerve Afferent: CN V Trigeminal Efferent: CN VII Facial Corneal reflex ? “Wrinkle up your forehead” “Scrunch your eyes closed” “Smile” CN VII – R Facial nerve palsy “Wrinkle up your forehead” “Scrunch your eyes closed” “Smile” Causes of CN VII lesions Unilateral LMN - Bell’s palsy - herpetic infections Bilateral LMN Unilateral UMN lesions - Cerebrovascular incidents Bilateral UMN lesions CN VII – Facial nerve damage Case report A 38-year-old man had a right inferior dental nerve block to allow the replacement of an amalgam restoration in his lower second molar tooth. Over 6 hours he developed a progressive ipsilateral facial weakness and hyperacusis was noted. He was referred for specialist opinion after returning to the dental practice the following day. Cousin GC Nerve palsy following intra-oral surgery performed with local anaesthesia R Coll Surg Edinb. 2000; 45(5):330-3. Examination of hearing and balance CN VIII - vestibulocochlear nerve Auditory Vestibular Rinne’s test Weber’s test Gait Nystagmus Hallpike manoeuvers CN VIII - vestibulocochlear nerve Rinne’s test (512hz) Weber’s test (256 hz) Test for conductive hearing Test for sensineural hearing loss Normal: Air > Mastoid process Normal: sound equal in both ears Examination of mouth and tongue CN V, CN VII, CN IX, CN X, CN XII Ask about taste Listen to the voice Inspection Uvula Gag reflex (not routine) Tongue CN V – lingual nerve (sensory branch of the mandibular division) The most common cause of Lingual Nerve Injuries is third molar surgery, with a reported incidence of 1-20% temporary and 0-2% permanent Renton & McGurk 2001; Renton & Yilmaz, 2011). CN IX – glossopharyngeal nerve Sensory: Posterior 1/3 of tongue, pharynx, middle ear Motor: Stylopharyngeus Autonomic: Salivary glands CN X – vagus nerve Sensory: Tympanic membrane, external auditory canal Motor: Palate, Uvula, Pharynx, larynx Autonomic: Lots of parasympathetic innervation CN IX and CN X Afferent: CN IX Glossopharyngeal Efferent: C X Vagus Inspect the Uvula Gag Reflex CN XII – Hypoglossal nerve Motor function ? CN XII – L Hypoglossal nerve palsy Small tongue - with fasciculations e.g. bilateral LMN lesions - with reduced movements e.g. bilateral UMN Unilateral tongue deviation - with wasting e.g. LMN lesion - with normal bulk e.g. UMN lesion Examination of neck and shoulders CN XI - Accessory nerve Examination of neck and shoulders CN XI - Accessory nerve Sternocleidomastoid Trapezius ? CN XI – R Accessory nerve palsy Abnormalities of CN XI Unilateral weakness (sternocleidomastoid/trapezius) - jugular foramen lesion IX ?, X ? Bilateral LMN lesion - Myopathy ? Syndromes with multiple CN abnormalities Syndromes with multiple CN abnormalities Cerebellopontine angle lesion unilateral V, VII, VIII Cavernous sinus lesion unilateral III, IV, V1, VI ? Horner syndrome due to sympathetic trunk damage Ptosis Anhidrosis Meiosis Enophthalmos congenital vs acquired Horner’s syndrome Central - e.g. stroke (hypothalamus, lateral medulla, upper cervical cord) - demyelination Peripheral - e.g. trauma, carotid dissection, aortic aneurysm, (Pancoast) tumor Systemic conditions with facial involvement Myotonic dystrophy Most common muscular dystrophy of adult life (1 in 8000) Subject to anticipation may feature malocclusion Risk of anaesthetic complications Myasthenia gravis Acquired weakness - AChR antibodies Variable weakness subject to variability Limb, ocular, bulbar, respiratory involvement Treatable ! Cranial nerve examination Quiz ! A? “Look to the your right” CN VI – R abducens nerve palsy X “Look to the your right” B? CN III – L oculomotor nerve palsy C? CN VII – R Facial nerve palsy D? CN XII – L Hypoglossal nerve palsy E? “Look to the your left” E Absent left corneal reflex (CN V, CN VII) Left lower facial nerve palsy (CN VII) Left lacteral rectus palsy (C VI) Cranial nerve examination Thank you for your attention [email protected]