Computer generated transcript

Warning!
The following transcript was generated automatically from the content and has not been checked or corrected manually.

Data Interpretation series Neurology – Cranial Nerves DeliverNegin Gholampoor BSC (Hons), Fourth year Student MBChBDisclaimer BIDA SW teaching is led by students with supervision of junior doctors and consultants across the UK. These teachings are created to support students’ learning but should not replace your local Medical School teaching material.Learning Outcomes Review Review the basic anatomy and function of 12 cranial Nerves Identify and differentiate between specific Recognize sensory, motor, or mixed functions of cranial nerves Apply your knowledge in clinical scenarios (specifically OSCE Stations) to diagnose Apply neurological disorders and recognise the clinical implicationsBasic principles - WIIPPPE • Wash your hands and put on personal protective equipment (PPE) • Introduce yourself • Identify your patient (Full name and DOB, ect) • Permission: Explanation of the examination and request for Consent (also request for consent to talk loudly to the examiner throughout the examination • Pain • Position: sat comfortably in a chair • ExposureOlfactory nerve (CN I) • Rthe forebrain.on: Nasal epithelium - nerve fibres travel directly to the olfactory bulb in • Innervation/Function: Special sensory – smell • In OSCE: simply ask if patient has experienced any recent changes to their sense of smell • Pathologies to consider: • Trauma (e.g., ethmoid bone fracture) • Space- occupying lesions (e.g., meningioma) • Infection (e.g., common cold, meningitis, sinusitis) • Congenital anosmia, Kallmann syndrome and primary ciliary dyskinesia (also known as Kartagener's syndrome) • Anosmia can be an early sign of Parkinson’s disease and Alzheimer’s disease.Case 1 • A 35-year-old female presented to the Neurology Clinic for evaluation of long-term neurological complaints as well as a chronic fatigue and lethargy. She has been experiencing changes in neurological functions, including heat intolerance leading to stumbling gait and falls, as well as fluctuating visual acuity over several years. She has reported that her symptoms worsened after a recent cold she had. nerve) is a hallmark of optic neuritis (3). • Please perform a cranial nerve examination on this patient and state the most likely underlying cause of her presentation(2).Optic nerve (CN II) • Receptor location: Retina and fovea • Innervation/Function: Special sensory – light handling and vision In OSCE: • Check visual acuity using Snellen chart • Offer to assess colour vision using Ishihara plates, • Evaluate visual fields • Test reflexes (accommodation reflex, direct and consensual and swinging light reflex) • Offer to perform ophthalmoscopy (1.Multiple Sclerosis Visual signs: • Optic neuritis (common presenting feature) • Optic atrophy • Uhthoff's phenomenon (worsening of vision following rise in body temperature) Internuclear Ophthalmoplegia (5) • Internuclear ophthalmoplegia • Investigations: MRI, CSF • Diagnosis: A diagnosis of the condition can be established based on either two or more relapses along with objective clinical evidence of multiple lesions, or objective clinical evidence of a single lesion along with reasonable historical evidence of a previous relapse (4). Optic nerve (CN II) – Visual acuity Causes of Painless Acute vison disturbances: Causes of Chronic vison disturbances: • Central retinal arterial occlusion/ Central • Primary open angle glaucoma retinal venous occlusion • Macular degeneration • Diabetic eye disease • Retinal detachment • Thyroid eye disease • Vitreous detachment • Giant cell arthritis Causes of Painful acute vison disturbances: • Acute angle closed glaucoma • Corneal ulcer • Optic neuritis This is not an exclusive listOptic nerve (CN II) – Visual field defects Side of lesion Field defect Common causes Optic nerve Ipsilateral monocular visual • Optic neuritis loos • Trauma • Optic atrophy Optic chiasm Bitemporal hemianopia • Pituitary adenoma (central) (tunnel vison) Optic chiasm nasal hemianopia •Internal carotid/posterior (lateral) communicating artery defect Optic tract Contralateral homonymous • Stroke (MCA) hemianopia • Space occupying lesions Optic radiation Contralateral homonymous • Stroke (MCA) quadrantanopia • Space occupying lesions (superior/inferior) • Trauma Occipital Contralateral homonymous • Stroke (PCA) cortex hemianopia with macular • Trauma sparingOptic nerve (CN II) – Visual field defects (6) Case 2 A 68-year-old male patient, who has a medical history of diabetes and has experienced a heart attack in the past, comes to the clinic with complaints of unusual changes in his vision. During a cranial nerve exam, you identify an inferior homonymous quadrantanopia while assessing the visual fields. Based on this presentation, the most probable location of the lesion is: 1. Inferior optic radiation in the temporal lobe 2. Inferior optic radiation in the parietal lobe 3. Inferior to the optic chiasm 4. Superior to the optic chiasm 5. Superior optic radiation in the parietal lobeOculomotor nerve (CN III) Trochlear nerve(CN IV) Abducens nerve(CN VI) Nuclei locations: • CN III and CN IV – Midbrain • CN VI – Pons • Function: Somatic motor – muscles of eye to allow smooth and coordinated eye movements and alignment. CNIII has an additional parasympathetic function LR6(SO4)3 CN6 -> supplies lateral rectus CN4 -> supplies superior oblique CN3 -> supplies the rest Case 3 You are examining a 54-year-old male patient with a past medical history of diabetes and temporal arthritis who presents with complaints of double vision. As you conduct your cranial nerve examination, you notice that when the patient looks straight ahead, his right eye turns downwards and outwards, resulting in a noticeable squint. When the patient attempts to look to his left, he is unable to adduct his right eye, and the double vision worsens. However, when he looks to the right, the angle of the squint is less pronounced. What is the most likely explanation for this case? 1. Left CNIII palsy 2. Right CNIII palsy 3. Right CN IV palsy 4. Left CNVI palsy 5. Right CNVI palsyCranial Distinct Presentation Common Causes nerve palsy CN III palsy • Affected eye looks down-and-out • Diabetes mellitus • Lesions of the autonomic portion result in • Vasculitis (e.g, SLE) loss of papillary reflex (afferent CNII, • Midbrain stroke (Weber's efferent CNIII) syndrome) • Ptosis • Multiple sclerosis • Dilated pupil CN IV palsy • Upwards and outward rotation • Diabetes mellitus • Exacerbated on downgaze - usually notified • Hypotension while walking • Congenital fourth nerve • Vertical or oblique diplopia – usually notified palsy while reading • Cavernous sinus thrombosis CN VI palsy • Horizontal diplopia – usually notified while • Diabetes mellitus looking at distance • Vasculitis • Inability to abduct the affected eye with • Tumor medial division of the affected eye • Cavernous sinus thrombosisCase 4 patient, it is observed that his jaw is deviated towards the right side, and a right-sided corneal reflex is absent. Which of cranial nerve is most likely to be affected?Trigeminal nerve (CN V) •Location of nucleus -pons, specifically in the motor nucleus and the sensory nucleus of the trigeminal nerve. •Innervation: Mixed •Function: Sensory innervation of face, motor Innervation of mastication muscles and corneal reflex (7)Trigeminal nerve (CN V) (8) Nerve palsy Distinct Presentation Ophthalmic ● Absent corneal reflex (afferent limb) nerve (V1) ● Loss of sensation in the ipsilateral forehead Maxillary nerve ● Loss of sensation in the ipsilateral midface (V2) Mandibular ● Loss of sensation of the ipsilateral lower ⅓ of the face and nerve anterior ⅔ of the tongue (V3) ● Paresis of ipsilateral muscles of mastication ● Deviation of jaw towards the side of the lesion due to unopposed action from the opposite pterygoid muscle ● Diminished/absent jaw jerk reflex (CN V3)Case 5 A 34 year old female who works as a secretary and spends 80% of the day sitting in front of a computer screen was taken to the hospital after her husband thought she was having a stroke due to a right-sided facial droop. PMH included a positive HSV1 test, HTN and Type II DM . She complained of trouble with speaking and drinking. Eye dryness also made it difficult for her to look at a computer screen for extended periods of time. ON examination she is unable to raise her eyebrows and when asked to smile, it is deviated to the left. • What is the cranial nerve affected in this condition? • Is this an UMN or LMN lesion?Facial nerve(CN VII) • Location of nucleus: Pontomedullary junction • Innervation: Mixed • Function: Supplies the skin behind the ear, taste to the anterior ⅔ of the tongue, the and parasympathetic supply to the lacrimal, sublingual and submandibular glandsFacial nerve(CN VII) Remember • LMN lesion will cause upper and lower facial paralysis • UMN lesion will cause lower facial paralysis only • In OSCE: test muscles of facial expression • Ctumours-acoustic neuroma,age: Trauma, schwanomma, cholesteatoma, medical and cosmetic procedures, Moebius syndrome, Bell’s palsy, Ramsay hunt syndrome, Lyme diseaseCase 6 A 21-year-old woman presents with acute onset vertigo and nausea. She had a prior episode of upper respiratory tract infection and no hearing loss. Physical examination revealed left-beating spontaneous nystagmus in primary gaze. The nystagmus decreased in right gaze and increased in left gaze. Brain MRI was normal. • Which cranial nerve is affected in this scenario? • What is the diagnosis? • What is another common condition seen which affects the inner ear and can present with similar symptoms?Vestibulocochlear nerve (CN VIII) • Nuclei: 4 vestibular nuclei: superior, lateral, dorsal medullaor-lie in the dorsal pons and located lateral to the inferior cerebellar peduncle • Innervation: Sensory • Function: Supplies the vestibular and cochlear systems of the inner ear for hearing and balanceVestibulocochlear nerve (CN VIII) • In OSCE: Test the vestibular division: Assess gait, Romberg’s test, object tracing for nystagmus Test the cochlear division: Otoscopic examination, crude hearing and conduction (Rinne and Weber tests) • Causes of CN VIII damage : Vestibular neuritis, congenital malformation, infection, vasculara, injury Case 7 A 10-year-old boy underwent surgery, a bilateral palatine tonsillectomy. During examination, the doctor noted the boy did not possess a gag reflex on the right side on the posterior tongue. He also complained of abnormal taste sensations in the back of his oral cavity. The soft palate elevated symmetrically when the gag reflex was tested. No other signs or symptoms were noted. • What cranial nerve was damaged? • Which other cranial nerve are you assessing when assessing a patient’s gag reflex?Glossopharyngeal nerve (CN IX) • Lmedullary regions of the brainstemwhich lie within the inferior pontine and • Innervation: Mixed- motor, sensory and parasympathetic • Function: 7 branches Supplies the tongue: Sensation from the posterior ⅓ of the tongue and pharynx, taste to the posterior ⅓ of the tongue, Motor to the stylopharyngeus Parasympathetic to the parotid glands, pharnyx and larynxGlossopharyngeal nerve (CN IX) In OSCE: Assess with the vagus nerve: Ask patient to cough. Use a palate should move up centrallyhe soft and posterior pharyngeal wall- soft Conditions: Glossopharyngeal neuritis, diphtheria, stroke, multiple sclerosis, neoplasms, trauma, iatrogenic (tonsillectomy)Case 8 A 70f presents with deviation of the uvula to the left side and asymmetry in the elevation of the soft palate, with the right side of the palate sagging. • What cranial nerve is most likely damaged?Case 9 A 68-year-old woman with thyroid cancer undergoes a total thyroidectomy. Postoperatively, the surgeon notes hoarseness and dysphonia, or altered voice production, while conversing with the patient. What nerve was damaged during the thyroidectomy? • (A) Lingual branch of glossopharyngeal nerve • (B) Accessory nerve • (D) Recurrent laryngeal nerve • (E) Hypoglossal nerveVagus Nerve(CN X) • Nuclei: Medulla oblongata and pons • Innervation: Mixed sensory, motor and parasympathetic • Function; Supplies skin around the ear, taste and sensation to the epiglottis, sensory information to the body visceral, parasympathetic to glands of GIT and motor innervation to soft palate, pharynx and larynxVagus Nerve(CN X) • In OSCE: Assess with CX IX: Ask patient to cough. Use a tongue depressor to visualise the soft palate and posterior pharyngeal wall- soft palate should move up centrally • Assess for ipsilateral paralysis of the soft palate, pharnyx and larynx- hoarseness of voice and ipsilateral soft palate asymmetry • Causes: Carotid aneurysms, trauma, neoplasmas, diphtheria, diseases which affect peripheral nerves such as diabetes and toxinsCase 10 A 23-year-old man presents with shoulder weakness and instability. After removing his shirt, his left shoulder appears to reside lower than his right shoulder with obvious asymmetry. During an examination, the patient is unable to abduct his left arm over his head and shows an inability to shrug (or elevate) his left shoulder against resistance. • What nerve was most likely damaged in this patient? • Wdamaged?her action could you ask patients to do to assess which nerve isAccessory nerve (CN XI) • Nuclei: Cranial (not considered true part of of the accessory nerve) and spinal. Spinal arises from the lateral aspect of ventral horn of superior cervical cord. • Innervation: Motor • Function: Supplies sternocleidomastoid and trapezius musclesAccessory nerve (CN XI) • In OSCE: Ask patent to shrug shoulders then apply resistance to assess weakness Turn head to assess weakness • Look for asymmetrical neckline, dropping shoulder, winged scapula (also occurs with long thoracic nerve damage), weakness on shoulder elevation • Causes: Iatrogenic injury- commonly cervical node biopsy and lymph node dissections, traumaCase 11 A 45-year-old man presents with speech difficulties and involuntary contractions within his tongue muscles. You note that his tongue deviates to the right when the patient attempts to protrude his tongue, as seen in the figure. • What nerve is most likely damaged in this patient?Hypoglossal nerve (CN XII) • Nuclei: Dorsal medulla oblongata • Innervation: Motor • Function: extrinsic and intrinsic muscles of the tongue • In OSCE: assess for tongue deviation, muscle wasting and fasciculationsKey points • Work systematically • If you forget something important- go back and assess • Complete examination by stating you would like to complete neurological examination of the limbs • Known conditions which affect each cranial nerve and important questions to ask in the historyReferences 1. Examination· DDBC. Cranial nerve examination - OSCE guide [Internet]. Geeky Medics. 2021 [cited 2023Apr15]. Available from: https://geekymedics.com/cranial-nerve-exam/ 2. Clinical presentation: Case history # 1 [Internet]. Multiple Sclerosis: Clinical Presentation- Case 1. [cited 2023Apr15]. Available from: https://library.med.utah.edu/kw/ms/clin_case01.html 3. Xxxxx. Finding multiple sclerosis during your eye exam [Internet]. Eyedolatry. [cited 2023Apr15]. Available from: https://www.eyedolatryblog.com/2014/07/finding-multiple-sclerosis-in-your-eye.html 4. Passmedicine. [cited 2023Apr15]. Available from: https://www.passmedicine.com/v7/menu.php 5. Internuclear ophthalmoplegia [Internet]. MedSchool. [cited 2023Apr15]. Available from: https://medschool.co/signs/internuclear-ophthalmoplegia 6. Visual field defects [Internet]. Pulsenotes. [cited 2023Apr15]. Available from: https://app.pulsenotes.com/specialities/ophthalmology/notes/visual-field-defects 7. The trigeminal nerve (CN V) [Internet]. TeachMeAnatomy. [cited 2023Apr15]. Available from: https://teachmeanatomy.info/head/cranial-nerves/trigeminal-nerve/ 8. Cranial nerve palsies - knowledge @ amboss [Internet]. ambossIcon. [cited 2023Apr15]. Available from: https://www.amboss.com/us/knowledge/Cranial_nerve_palsies/ 9. https://www.ninds.nih.gov/archived/bells-palsy-fact-sheet 10. https://www.cedars-sinai.org/health-library/conditions-and-treatments.html 11. https://www.ncbi.nlm.nih.gov/books/NBK386/#:~:text=Causes%20include%20meningitis%2C%20carotid%20aneurysms,produce%20neuropat hies%20of%20these%20nerves. 12. Shikino K, Ikusaka MAlexander’s law in vestibular neuritisBMJ Case Reports CP 2021;14:e239705. 13. https://www.chegg.com/flashcards/lippincott-cranial-nerve-questions-23daa4dc-b439-4121-8efe-ca0554ac3d03/deck 14. Walker HK. Cranial Nerves IX and X: The Glossopharyngeal and Vagus Nerves. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 63. Available from: https://www.ncbi.nlm.nih.gov/books/NBK386/FOR FEEDBACK AND QUERIES: Email @ info@bidasw.com