Wk12 - Neurology Flashcards
What are the cranial nerves?
12 pairs of nerves that emerge from brainstem and supply head and neck
Sensory, motor and parasympathetic activity
I-XII
Cranial nerve abnormlaities may arise form lesions affecting..
communicating pathways to and from the cortex, cerebeluum and other part s of brainstam Nerve nucleus Nerve Neuromuscular junciton disorders Muscle
Name the 12 CNs and whether they are sensory, motor or both (parasympathetic)
And what part of the brainstem these nerves arise from
I - Olfactory - Sensory II- Optic - Sensory III - Oculomotor - Motor IV - Trochlear - Motor V - Trigeminal - Both - parasympathetic VI - Abducens - Motor VII - Facial - Both - parasympathetic VIII - Vestibulocochlear - Sensory IX - Glossopharangeal - Both - parasympathetic X - Vagus - Both - parasympathetic XI - Spinal accessory - Motor XII - Hypoglossal - Motor
Olfactory nerve
Function - smell
Tract: olfactory cells of nasal mucosa –> olfactory bulbs –> pyriform cortex
What are the nerves that move the muscles of the eye
Trochlear
Occulomotor
Abducens
Oculomotor nerve
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Oculomotor nerve
Motor component:
Nucelus located in midbrain (oculomotor)
Function - movement of eyeball and lens accomodation
Structure innervated - inferior oblique, superior, medial and inferior recti muscles, levator palpebrae superioris
Parasympathetic component:
Nucleus located with midbrain (Edinger-Westphal)
Function: pupil constriction
Structures innervated - ciliary muscle and pupillary constrictor muscles
Trochlear nerve
Motor
Function - moves eyeball
Nucleus located in midbrain (inferior colliculus)
Structure innervated - superior oblique muscles
Depresses the adducted eye and intorts the abducted eye
Longest intracranial course
II and IV are only nerves to decussate to contralateral side
Pattern of internuclear opthalmoplegia
Disorder of conjugate gaze - failure of adduction of affected eye with nystagmus on lateral gaze in contralateral eye
Can be unilatral of bilateral
Results from lesion of medial longitudinal fasiculus
Commonly seen in multiple sclerosis
Pattern of internuclear opthalmoplegia
Disorder of conjugate gaze - failure of adduction of affected eye with nystagmus on lateral gaze in contralateral eye.
Can be unilatral of bilateral
Results from lesion of medial longitudinal fasiculus
Commonly seen in multiple sclerosis
Features seen in Horner’s syndrome
Consists of: miosis, ptosis, apparent enopthalmos, anhidrosis
Results from ipsilateral disruption of cervical/thoracic sympathetic chain:
- congenital, brainstem stroke, cluster headache, apical lung tumour, MS, carotid artery dissection, cervical rib, syringomyelia
Trigeminal nerve
Component 1 - Sensory input from face
Nucleus in pons and medulla
Structure innervated - face (ophthalmic, mandibular and maxillary division) and anterior 2/3rd of tongue
Motor component 2 - function = mastication
Nucleus located in pons
Structure innervated - masseter, temporalis, medial and lateral pterygoids
Herpes zoster ophthalmicus
Pain may precede vesicles Lifetime risk of 1% V2/V3 rarely affected Elderly and immuno-compromised at risk Treated with oral aciclovir
Facial nerve
Motor - nucleus in pons. Function - muscles of facial expression
Sensory - nucleus in medulla
Function - taste
Structures innervated - anterior 2/3 of tongue
Parasympathetic - nucleus on medulla.
Function - taste
Structure innervated - anterior 2/3 of tongue
Glossopharyngeal plasy affecting uvula…
Glossopharangeal palsy with deviation of uvula away from the side of the lesion
Spinal accessory nerve
Motor
Head rotation and shoulder
Nucles in medulla
Innervates sternocleidomastoid and trapezius muscles
Turn head against resistance - sternocleidomastoid m
Shrug shoulders
Vestibulocochlear
1 - Sensory. Function - balance. Nucleus - pons and medulla. Structure innervated - nerve endings within semi-circular canals –> cerebellum and spinal cord
2 - Sensory. Function - hearing. Nucleus in pons and medulla. Structure innervated –> auditory cortex in the temporal lobes
Mononeuropathy of ulnar nerve
Most common cause of palsy - entrapment at ulnar groovw (medial epicondyle of humerus)
Presenting symptoms - may be history of trauma; sensory disturbance and weakness (weak grip), usually painless
Motor weakness:
Glossopharangeal nerve
1 - Sensory. Nucleus in medulla. Function - taste, proprioception for swallowing, blood pressure receptors.
Structure innervated - Posterior 1/3 of tongue, pharangeal wall & carotid sinuses
2 - Motor. Nucleus in medulla. Function - swallow and gag reflex, lacrimation.
Structure innervation - pharangeal muscles, lacrimal glands
3 - Parasympathetic
Glossopharyngeal palsy affecting uvula…
Glossopharangeal palsy with deviation of uvula away from the side of the lesion
Vagus nerve
Sensory - nucleus in medulla. Function - chemoreceptors, pain receptors (dura), sensation.
Structure innervated - blood oxygen conc, carotid bodies, resp and digestive tracts, external ear, larynx and pharynx
Motor - Nucleus in the medulla. Function - heart rate and stroke volume; Peristalsis; Air flow; Speech and swallowing
Structure innervated: Pacemaker and ventricular muscles; smooth muscles of the digestive tract; smooth muscles in bronchial tubes; muscles of larynx and pharynx
Parasympathetic: Structure innervated - smooth muscles and lgands of the same areas innervated by motor component, as well as thoracic and abdominal areas
Spinal accessory nerve
Motor: Function: Head rotation and shoulder
Nucleus in medulla
Innervates sternocleidomastoid and trapezius muscles
Turn head against resistance - sternocleidomastoid muscle
Shrug shoulders - trapezius muscle
Hypoglossal nerve
Motor: Function: Speech and swallowing. Nucleus located in medulla. Structure innervated - tongue
What cranial nerves are affected by a lesion in:
Cavernous sinus Superior orbital fissure CErebellopontine angle Jugular foramen Bulbar/pseudobulbar palsy
Cavernous sinus - III, IV, V (1st and 2nd divisions), VI
Horner’s syndrome
Superior orbital fissure - III, IV, V (1st division), VI
Cerebellopontine angle - V, VII, VIII
Jugular foramen - IX, X (and XI)
Bulbar/pseudobulbar palsy - IX, X, XI (and XII)
Mononeuropathy of radial nerve
Most common cause of palsy - entrapment at spiral groove, Sat night palsy
Presenting symptoms - wrist and finger drop, usually painless
Motor weakness:
Extensor carpi radialis longus - weakness in wrist extension
Extensor digitorum communis - weakness in finger extension
Brachioradialis - weakness in elbow flexion in mid-pronation
Mononeuropathy of ulnar nerve
Most common cause of palsy - entrapment at ulnar groove (medial epicondyle of humerus)
Presenting symptoms - may be history of trauma; sensory disturbance and weakness (weak grip), usually painless
Motor weakness:
1st dorsal interosseus - weakness in index finger abduction
Abductor digiti minimi - weakness in pinkie abduction
Flexor carpi ulnaris - weakness in wrist flexion
Adductor polilicis - weakness in thumb adduction
Mononeuropathy of median nerve
Most common cause of palsy - entrapment with carpal tunnel at wrist
Presenting symptoms - history of intermittent nocturnal pain, numbness and tingling - often relieved by shaking hand; Patient may complain of ‘weak grip’; Positive Tinel’s sign/ Phalen’s test
Motor weakness:
Lumbricals I+II - weakness in flexion at MCP joints
Opponens pollicis - weakness in thumb opposition
Abductor pollicis brevis - weakness in thumb abduction
Flexor pollicis brevis -w eakness in thumb flexion
Mononeuropathy - median nerve II Anterior Interosseous branch
Most common cause of palsy - trauma to forearm
Presenting symptoms - history of forearm pain; Patient may complian of ‘weak grip’ of keys; Positive Tinel’s sign/ Phalen’s test
Motor weakness:
Pronator quadratus - weakness in flexion at MCP joints
Flexor pollicus longus - weakness in thumb flexion
Flexor digitorum profundus (lateral) - weakness in thumb flexion
Can’t do the ‘OK’ sign
What are the 3 thigh nerves
Front - femoral = quads
Medial - obturator = abduction
Back - Sciatic = Hamstrings
Mononeuropathy of femoral nerve
Most common cause of palsy - haemorrhage/trauma
Presenting symptoms - weakness of quadriceps, weakness of hip flexion and numbness in medial shin
Motor weakness:
Quadriceps - weakness in knee extension
Illiopsoas - weakness in hip flexion
Adductor magnus - weakness in hip adduction
Pathogenesis and investigation of myasthenia gravis
Autoimmune disroder: antibodies to acetylcholine receptor at post-synaptic receptor at post-synaptic NMJ
Association with other autoimmune disorders
May be associated with thymic hyperplasia or thymoma
Affects young women in 20’s and older men in 70’s
Fatigueable weakness of ocular, bulbar, neck, resp and/or limb muscles
Mononeuropathy of common peroneal nerve
Most common cause of palsy: Entrapment at fibular head (crossing legs)
Presenting symptoms: May be history of trauma, surgery or external compression; Acute onset foot drop + sensory disturbance; Usually painless
Motor weakness:
Tibialis anterior - ankle dorsiflexion
Extensor hallucis longus - Great toe extension
Mononeuritis Multiplex
Simultaneous or sequential development of 2 or more nerves.
Common causes: Diabetes, Vasculitic (Churd Strauss, polyarteritis nodosa), Rhematological (RA< lupus, Sjogren’s syndrome), Infective (Hep C, HIV), Sarcoidosis, Lymphoma
Management depends on underlying cause
Functions of PNS
Sensory input to CNS
Motor output to muscles
Innervation of viscera
Incoming sensory information enters via posterior root. Motor information exits cord via anterior root.
Collections of nerve cell bodies in PNS known as ganglia
Structure of peripheral nerves
Organisation of a peripheral nerve in fascicles and their protective connective tissue layers.
Fibre types: Large fibres (myelinated) - motor nerves; Proprioception, vibration and light touch. Thinly myelinated fibres: Light touch, pain and temperature Small fibres (unmyelinated) - light touch, pain and temperature
Anatomy of the PNS
Upper limb nerves Lower limb nerves Cervical plexus Lumbar plexus Nerve roots Neuromuscular junction and muscle
Clinical presentation of neuropathy
Motor neuropathy –> weakness/muscle atrophy
Sensory neuropathy:
Large (myelinated) fibres –> sensory ataxia, loss of vibration sense +/- numbness and tingling
Small (thinly myelinated/unmyelinated) fibres –> impaired pin prick, temperature, painful burning, numbness and tingling
Autonomic –> postural hypotension, erectile dysfunction, GI disturbance, abnormal sweating
Tendon reflexes may be reduced or absent
Length-dependednt axonal neuropathy
Limb dependent neuropathy
Starts distally and spreads proximally
‘Glove and stockings’
Age >50 years Length dependent: starts in toes/feet Symmetrical Slowly progressive No significant sensory ataxia Any weakness is distal and mild
Axon of the nerve is most commonly affected
Promdrome of migraine
Reported by 40-60%…
Acute inflammatory demyelinating neuropathy “Guillain-Barre syndrome”
Post-infectious autoimmune aetiology (e.g. campylobacter, CMV, EBV)
Progressive (ascending) weakness over days
Flaccid, quadraparesis and areflexia
+/- respiratory/bulbar/autonomic involvement
Treated with intravenous immunoglobulin or apheresis
CIDP: chronic form (steroid and IVIG responsive)
Causes demyeliantion causing weakness
Pathology is not in the axon, it is in the myelin sheath
Diagnosis of Guillian barre syndrome
Nerve conduction test ==> tests motor and sensory nerves by applying stimulation and recording the response
High protein in CSF and demyelination seen in nerve conduction test ==> diagnostic of Guillian barre syndrome
Symptoms of muscle disease
Proximal limb weakness - difficulty raising arms above head, arising from seated position
Facial weakness - myopathic facies, drolong
Eyes - ptosis, ophthalmoplegia
Bulbar - dysarthria, dysphagia
Neck and spine - head drop, scoliosis
Resp - breathlessness
Myocardial - exercise intolerance, palpitations
Causes of muscle disease
Muscular dystrophies - Dystrophinopathies (Duchenne/Becker), fascioscapulopulohumeral (FSH) dystrophy, limb girdle, oculopharyngeal
Metabolic muscle disorders - glycogen storage disease, deefcts of fatty acid metabolism
Mitochondrial disorders
Myotonic dystrophies
Inflammatory muscle disorders - Polymyositis, dermatomyositis, inclusion body myositis
Neuromuscular junction disorders - myasthenia gravis, Lambert Eaton syndrome
Pathogenesis and investigation of myasthenia gravis
Autoimmune disorder: antibodies to acetylcholine receptor at post-synaptic receptor at post-synaptic NMJ
Association with other autoimmune disorders
May be associated with thymic hyperplasia or thymoma
Affects young women in 20’s and older men in 70’s
Fatigueable weakness of ocular, bulbar, neck, resp and/or limb muscles
Investigation and management of myasthenia gravis
Antibodies to AChR present in 85% of cases
Single fibre EMG and repetitive nerve stimulation also abnormal
Managed with Pyridostigmine (anti-acetylcholine esterase) and immunosppuressive therapies (e.g. steroids and intravenous immunoglobulin).
Removal of thyroid tumour
Primary vs secondary headaches
Primary = headache and its associated features is the disorder (no underlying cause) e.g. migraine, tension-type headache, cluster headache etc.
Secondary = secondary to underlying to cause e.g. subarachnoid haemorrhage, space-occupying lesion, meningitis, temporal arteritis, high/low intracranial pressure, drug-induced
Causes of thunderclap headache
Subarachnoid heamorrhage (approx 15% of thunderclap headache)…
Red flags suggesting secondary headache
Age>50 years
Thunderclap headache (sudden onset, strongly associated with subarachnoid haemorrhage)
Worsening of symptoms with posture change, valsalva (coughing, straining) or physical exertion (high intracranial pressure)
Early morning headahces
systemic - fever, weight loss –> worried about infection or malignancy
Seizures, meningism
Temporal artery tenderness/jaw claudication –> temporal arteritis (high levels of inflamm marker e.g. CRP, ESR)
Specific situations cause inc. risk of secondary- cancer, pregnancy, post-partum (more coagulopathic is pregnant or post-partum –> causing blood clots), HIV/immunnosuppression
SNOOPT
Systemic symptoms
Neurological signs or symptoms
Older age at onset
Onset is acute (under 5 minutes)
Previous headache history is different/absent
Triggered headache (vaslsalva or posture)
Clinical examination of patient with headache
Abnormal signs suggest secondary cause:
General/Sysgtemic:
Red. conscious level, red. pulse/BP, pyrexia, meningism, skin rash, temporal artery tenderness
Cranial nerve: Pupillary responses, visual fields +/- bind spot, eye movements, fundoscopy
Epidemiology of migraine
Female> Male
Prevalence highest aged 25-55 y/o
Positive family history
Most patients report triggers - e.g. hormonal (menstrual), weather, stress, hunger, sleep disturbance, exertion, alcohol excess, food
Types of migraine
Migraine without aura (70%)
Migraine with aurua (30%)
Migraine pathophysiology
Primary dysfunction in brainstem sensory nuclei (V, VII-X);
Pain results from pain sensitive cranial blood vessels and their innervating trigeminal fibres
Aura - cortical spreading depression
Migraine headache - activation of trigeminovascular system (with CGRP and other neuropeptides)
Phases of migraine
Prodrone - hours or days before headache ‘feel one coming on’
Aura
Headache + associated features
Postdrome
Prodrome of migraine
Reported by 40-60%
up to 48 hours before headache
Variable symptoms: mood disturbance/restlessness/hyperosmia/photophobia/diarrhoea
Aura
Recurrent reversible focal neurological symptom (e.g. visual, sensory, motor)
Develops over 5-20 mins and lasts <60 mins
Visual aura is most common (e.g. scotoma, flashing lights, fortification spectrum)
Sensory aura often starts in hand and migrates up arm
Examples of visual aura: Zigzag fortification spectrum Visual field loss Negative scotoma Positive scotoma
The headache phase of migraine
Character of headache commonly throbbing or pulsatile Moderate - severe intensity Gradual onset, duration 4-72 hours Unilateral in 60%, can radiate. Aggravated by routine physical activity
Associated symptoms of headache with migraine
Nausea and vomiting, photophobia, phonophobia, osmophobia, mood disturbance, diarrhoea, autonomic disturbance: e.g. lacrimation, conjuctival injection, nasal stuffiness
Investigation of migraine
Good history and normal clinical examination does not require further investigation
Cranial imaging advised if ‘Red Flag’ features present or aura >24 hours
Complications associated with migraine
Medication overuse headache (MOH): headache 15+ days per month associated with frequent use of acute relief medications (e.g. NSAIDs, paracetamol, opioid, analgesia, triptans) - patients advised to take acute treatments no more than 2-3 times per week to prevent MOH
Chronic headache: headache on 15+ days per month
Management of migraine
Lifestyle - avoid triggers, reduce caffeine/alcohol intake, encourage regular meals and sleep patterns
Acute management - simple analgesia (e.g. paracetamol, aspirin, NSAIDs), Triptans (e.g. Sumatriptan)
Antiemetic (e.g. metoclopramide)
Prophylaxis:
Beta-blockers (e.g. propanolol)
Tricyclic antidepressants (e.g. Amitriptyline, Nortriptiline)
Anti-epilepsy drugs (e.g. Topiramate, Sodium Valproate)
Definition of thunderclap headache
Abrupt-onset of severe headache which reaches maximal intensity >5 mins (and lasts >1hr)
‘Worst headache of life’
‘Like being hit over the head’
Should be considered as subarachnoid haemorrhage (SAH) until proven otherwise
Causes of thunderclap headache
Subarachnoid heamorrhage (approx 15% of thunderclap headache)
Intracerebral haemorrhage
Arterial dissection (vertebral or carotid)
Cerebral venous sinus thrombosis
Bacterial meningitis
Rare - spontaneous intracranial hypotension, pituitary apoplexy
Primary headaches (e.g. migraine, exertional headache, cluster headaches) - diagnosis of exclusion
