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Cranial nerves
Trigeminal nerve
Trigeminal nerve
V: Trigeminal (3 nerves in 1!)
•
V1. Ophthalmic
– Exits with eye muscle group (superior orbital fissure, through orbit to superior
orbital notch/foramina)
– Sensory to forehead, nasal cavity
•
V2. Maxillary
– Exits foramen rotundum through the wall of maxillary sinus to inferior orbital
foramina)
– Sensory to cheek, upper lip, teeth, nasal cavity
•
V3. Mandibular
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Exits foramen ovale to mandibular foramen to mental foramen
Motor to jaw muscles--Masseter, temporalis, pterygoids, digastric
Sensory to chin
Sensory to tongue
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Trigeminal neuralgia
TRIGEMINAL NEURALGIA
(Tic Douloureux)
•
A disorder of the trigeminal nerve producing bursts of
excruciating, lancinating pain, lasting between seconds and
2 min, along the distribution of one or more of its sensory
divisions, most often the maxillary.
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vascular loops compressing the trigeminal nerve root where it
enters the brainstem
usually adults
trigger point or by activity (eg, chewing or brushing the teeth).
Although each bout of intense pain is brief, successive bouts
may be incapacitating.
TRIGEMINAL NEURALGIA
Differential diagnosis
•
•
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Neoplasm
Vascular malformation of the brain stem,
Vascular insult,
Multiple sclerosis (especially in a younger patient).
Postherpetic pain
–
•
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typical antecedent rash, scarring, and predilection for the
ophthalmic division.
Sjögren's syndrome or RA, (with a sensory deficit that
is often perioral and nasal).
Migraine may produce atypical facial pain, with
normal examination results, but the pain is more
prolonged and is burning or throbbing.
Treatment
•
carbamazepine (Tegretol®), fenitoin (Dilantin®), oxcarbazepine
(Trileptal®), gabapentin (Neurontin®).
– Use of Baclofen (Lioresal®) may increase efficiency
•
Neurontin®, (gabapentin), Lyrica ® (pregabalin) – lower rates of
adverse effects
Surgical treatment
• Percutaneous risotomy (glycerol injection, baloon
compression, radiofrequency risotomy)
• Peripheral blocks, section, avulsion
• Microsurgery risotomy
• Gammaknife radiosurgery
Trigeminal paralysis
• Weakness, hipotonia and
atrophies of the maseter and
temporal muscles
• Jaw deviates towards affected
side upon closure of the mouth,
• can not perform jaw lateral
movements to the affected side
Facial nerve
Branchial
motor
(special
visceral
efferent)
Supplies the muscles of
facial expression;
posterior belly of
digastric muscle;
stylohyoid, and
stapedius.
Visceral
motor
(general
visceral
efferent)
Parasympathetic
innervation of the
lcrimal,
submandibular, and
sublingual glands, as
well as mucous
membranes of
nasopharynx, hard
and soft palate.
Special
sensory
(special
afferent)
Taste sensation from the
anterior 2/3 of
tongue; hard and
soft palates.
General
sensory
(general
somatic
afferent)
General sensation from
the skin of the
concha of the auricle
and from a small
area behind the ear.
Bell's Palsy
•
Unilateral facial paralysis of sudden onset and unknown cause.
•
swelling of the nerve due to immune or viral disease, with ischemia
and compression of the facial nerve in its course through the temporal
bone.
Pain behind the ear may precede facial weakness.
Weakness develops within hours, sometimes to complete paralysis.
The patient may complain of a numb or heavy feeling in the face, but
no sensory loss is demonstrable.
•
•
•
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A proximal lesion may affect salivation, taste, and lacrimation and
may cause hyperacusis.
Differential Diagnosis
•
Disorders of the facial nerve or its nucleus, chiefly geniculate herpes
(Ramsay Hunt's syndrome),
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Middle ear or mastoid infections,
•
Sarcoidosis,
•
Lyme disease,
•
Petrous bone fractures,
•
Carcinomatous or leukemic nerve invasion,
•
Chronic meningeal infections, and
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Cerebellopontine angle or glomus jugulare tumors.
•
Temporal bone fracture
Bell’s Palsy
•
Treatment
– Oral antivirals - Acyclovir - 10mg/kg (500mg) q8hrs x 7 days
– Corticosteroid
• Prednisone taper 1mg / kg / day for 10 days
• methylprednisolone
– Eye protection - lacrilube
– Follow progression with serial exams
– Facial nerve decompression
• Performed before irreversible injury to the endoneural tubules occurs (two weeks), will
allow for axonal regeneration to occur
What if the facial paralysis doesn’t
resolve?
• End-to-End Anastomosis
• Cable Nerve Graft
• Hypoglossa-Facial Nerve Anastomosis (Crossover or
Jump Graft)
• Muscle transposition (Gracilis)
• Static Suspension (Gortex, Threads)
Complications
• Keratitis
• Emotional/Social Issues
• Synkinesis
Ramsay Hunt Syndrome
Central vs
peripheral
paralysis
Weakness of the entire
half of the face
distinguishes Bell's
palsy from
supranuclear lesions
(eg, stroke, cerebral
tumor), in which the
weakness is partial,
affecting the frontalis
and orbicularis oculi
less than the muscles
in the lower part of
the face
Oculomotricity
Centre for slow following
motions.
Activation leads to slow
deviation of eyes
Centre for saccadic (fast)
voluntary or reflex movements.
Activation leads to fast deviation
of eyes towards opposite side
Fronto-mezencephalic
pathway
Occipito-mesencephalic
pathway
III rd nerve nucleus
(both pathways end in the
oculomotor nerves nuclei)
Medial longitudinal
bundle
Reticular paramedian
pontine formation – centre
for lateral
Ocular motricity
Muscle
Inervation
Primary action
Secondary action
Medial rectus
N III
Adduction
superior rectus
N III
Elevation
Internal rotation
Adduction
inferior rectus
N III
Depressor
External rotation
Adduction
inferior oblique
N III
External rotation
elevation
Abduction
Superior oblique
N IV
Internal rotation
Depressor
Abduction
lateral rectus
N VI
Abduction
--
--
Other actions
--
--
3rd nerve - Oculomotor nerve
•
Somatic fibers: 4 out of the 6 extraoculary muscles and also the elevator of the
upper lid
–
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Control of the eye movements during following or fixation movements
Visceral fibers: parasympathetic fibers for the pupilar constrictor and ciliary
muscles
–
Involved in the accomodation pupilary reflexes
3rd nerve - Oculomotor nerve
VI th nerve
abducens
6th nerve – Abducens nerve
Abducens nerve palsy (left side)
4th nerve –
Trochlear nerve
Trochlear nerve
•
Contraction of the superior oblique muscle generates depression, internal rotation and abduction of
the eye
–
Lesions of the 4th nervegenerate
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External rotation (unbalanced action of inferior oblique muscle)
Diplopia (vertical)
Problems with looking down, especially for the eye that looks internally – problems with descending stairs
Compensatory rotation of the head
Due to its long way around the brainstem, the 4th nerve is prone to lesions in head trauma
Special features:
Trasaturi speciale:
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Theonly cranial nerve that emerges on the posterior side of the midbrain
All fibers from the lower motor neuron cross
It has the longest intracranian passage
Contains the least axons compared to the other cranian nerves
trohlear
•
normal
•
Superior
oblique
muscle
palsy
joint deviation
of the eyes and
head
Internuclear palsies
Miasthenia gravis
The Anatomy of the
Neuromuscular Junction
• Motor neurone terminates as a bouton or presynaptic nerve terminal separated from the
muscle by a thin synaptic cleft (Motor endplate)
• The blood nerve barrier is relatively deficient at
the NMJ
• Nerve and muscle are kept in close proximity by
bridging protein (laminin), with release zones
and the crests of post synaptic folds aligned
• The skeletal neuromuscular junction is the most
studied and best understood synapse
Healthy Neuromuscular Junction
The Physiology of Neuromuscular
transmission
• Neuronal Action potential invades the presynaptic nerve terminal
• Depolarisation triggers opening of VGCCs
• Calcium influx triggers quantal release of ACh
• ACh binds to post synaptic nAChRs
• Ca and Na ions influx through nAChR triggering
muscle membrane depolarisation via VGSCsCMAP and muscle contraction
Spontaneous and Nerve Evoked
Endplate Responses
Myasthenia Gravis (MG)
• MG is the most common disorder of neuromuscular
transmission
• Incidence 2-6 per 106 , prevalence 40 per 106 population
• MG is an acquired autoimmune disease characterised by
the formation of anti- nAChR antibodies
• MG is common in young women, and older men
• MG is characterized by fluctuating and fatigable
weakness
• Weakness may be limited to a few muscles, such as the
extraocular muscles, bulbar, limb or be generalised in
fashion
•
Myasthenia Gravis (MG)
• Ocular features: ptosis, diplopia,
ophthalmoplegia
• Facial weakness esp ob oculi and oris
(snarl)
• Bulbar weakness: nasal speech, reduced
gag, swallowing
• problems, aspiration (silent), weak neck
(dropped)
• Limb weakness: proximal, fatiguable
• Reflexes: normal
Fenomenul de oboseală
• Respiratory weakness: diaphragm and (ptoză) în MG
intercostal
Myasthenia Gravis (MG)
• MG is a defect of neuromuscular transmission with
– reduced efficacy of Acetyl Choline at the post synaptic motor
endplate due to pathogenic antibodies which
• Block the nAChR,
• Down regulate the nAChR
• & cause complement dependent destruction of the motor endplate
Myasthenia Gravis (MG)
• The immunopathogenesis of MG is unclear but involves
• Genetic factors (HLA B8)
• Thymus
– Vast majority of young onset cases are autoimmune and
associated with thymic hyperplasia
– Around 10% of patients with MG, often older patients) have an
associated thymic tumour (oft striated muscle Abs)
• Seronegative (10% gen, 50% OMG)
• Neonatal MG
Myasthenia Gravis (MG)
• Diagnosis
– Typical clinical picture
– Detection of anti-AChR
antibodies in serum (90%)
– Positive Tensilon test
(atropine)
– Repeptitive nerve stimulation
at low frequency leads to a
decrement in compound
muscle action potential
amplitude
Tensilon test – before and after
Single fiber EMG
– normal
Single fiber EMG
– increased jitter
Repetitive Nerve Stimulation
(Supramaximal 2Hz)
Myasthenia Gravis (MG)
• Treatment
– Symptomatic (pyridostigmine oft with probatheline)
– Thymectomy
• Hyperplasia (trans-sternal approach),
• Thymoma (locally invasive)
– Immunotherapy
• steroids, and other agents including Azathioprine
• plasma exchange,
• IVIG
Lambert Eaton Myasthenic syndrome
(LEMS)
• A defect of neuromuscular transmission with reduced
quantal release of Acetyl Choline from the presynaptic
nerve terminal
• Pathogenic antibodies directed against voltage gated
calcium channels (VGCCS) expressed at the NMJ and
autonomic ganglia
• 2/3 patients with LEMS have cancer, most commonly
Small cell lung Ca (express VGCCs)
Lambert Eaton Myasthenic syndrome
(LEMS)
• Clinical features
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Dry mouth
Fatigable weakness of proximal muscles (like MG)
Wasting of proximal muscles (X MG)
Depressed reflexes (X MG)
Ocular and bulbar weakness rare (X MG)
Lambert Eaton Myasthenic syndrome
(LEMS)
• Diagnosis
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–
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Typical clinical picture
Detection of anti-VGCC antibodies in serum
Positive Tensilon test (like MG)
Repeptitive nerve stimulation at low frequency leads to a
decrement in compound muscle action potential amplitude (like
MG)
– Repeptitive nerve stimulation at high frequency leads to a
increment in compound muscle action potential amplitude (X MG)
Repetitive Nerve Stimulation
(Supramaximal 2Hz)
Lambert Eaton Myasthenic syndrome
(LEMS)
• Treatment
– Treating the underlying lung tumour improves LEMS
– Treatment for LEMS per se
• Symptomatic (mestinon, 3-4 DAP)
• Immunotherapy (steroids, plasma exchange, IVIG)
POLYMYOSITIS
DERMATOMYOSITIS
CLASSIFICATION OF
POLYMYOSITIS DERMATOMYOSITIS
• Group I: Primary Idiopathic PM
• Group II: Primary Idiopathic DM
• Group III: DM or PM associated with neoplasia
• Group IV: Childhood DM or PM associated with vasculitis
• Group V: PM or DM with associated with collagen
diseases
POLYMYOSITIS DERMATOMYOSITIS
• Onset age: Usually > 20 years
• Progression: weeks-months
• Possibly preceded by upper tract infection
• Other possible trigger factors:
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Anti hepatitis B vaccination
Growth hormone administration
Drugs: penicilamine
Viral infections: Coxsackie B; Parvovirus; Echovirus
HLA
• Class II: antigens DQα1*0501 (88%)
• For DM: DMA*0103 si DMB*0102
Clinical Picture
• Muscle weakness
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Proximal > Distal
Symmetric
Frequently starts at lower limbs
Selective regions of weakness:
eophagus (dysphagia); Posterior neck;
Quadriceps
– Usually does not affect oculomotor
muscles
– Amiotrophies occur late in the evolution
– Reflexes usually normal
Motor deficit
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Proximal: most frequently in PM and DM
Distal: inclusion body myositis
Lack of simmetry: inclusion body myositis
cvadriceps: inclusion body myositis; PM with
mitochondrial diseases
Extraocular muscles: extraoculary myositis
Swallowing : inclusion myositis, granulomatous myositis,
scleroderma associated myositis
Episodic: episodic miopathy with pipestem capilaries
Acute: infectious;
Skin lesions (DM)
• Heliotrope rash - reddish violaceous
eruption on upper eyelids +/- oedema
• Diffuse/localised erythema over chest,
neck, or over forehead, chin, malar
area
• Gottron’s sign - symmetric violaceous
erythematous eruption over knuckles
• Necrosis
Gottron
sign
Pain
• Pain
– 30%; Especially with associated connective tissue disease
– Rule out: Polymyalgia; Arthritis; Fasciitis; Rhabdomyolysis
• Muscle pain
– Associated with contraction, muscle mass compression or
spontaneous pain
• Joint pain
– Arthrites or nondestructive arthralgia
– Anti-Jo1 or AntiARNt synthethasys antibody syndromes
Associated disorders
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•
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Cardiac: Arhythmias; Inflammatory cardiomyopathy
Pulmonary: Respiratory muscle weakess; Interstitial lung
disease
Esophageal paresis: Upper 1/3 with muscle weakness,
Lower 2/3 with scleroderma
Abdominal pain:
– GIT mucosal involvement
– Marked by ulceration, hemorrhages & perforation
– Due to associated vasculopathy
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•
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Malignancy: Mild increased risk
Autoimmune:Lupus, Sjoegren's, Anti-phospholipid
antibodies & syndrome: 5% to 8%
Thyrotoxicosis: Rare
– High CK: CK in hyperthyroid is usually low
– May resolve with anti-thyroid medication alone
•
Calcinosis (formation of calcium deposits in any soft tissue)
in 1/3 of cases
Clinical forms (evolutive)
• Acute:
– Important motor deficit, fast prograssion, muscle pain,
fever, inflamation signs, myoglobinuria
– Possible death within weeks due to reapiratory
destress, heart failure, kidney feilure
• Subacute
• Cronic
• Focal forms – rare; sometimes evoluate towards
difuse type
Laboratory
• Serum CK: High (3 to 30 times normal); elevated LDH,
aldolase, AST, ALT
• General inflamation signs (CRP)
• EMG: Irritative myopathy
– Small amplitude, brief, polyphasic motor units
– Fibrillations; Positive sharp waves
– spontaneous high frequency discharges
• Antibodies: Disease specific & non-specific
EMG aspects
Polyphasic action
potentials with
small amplitude,
short duration
Long duration positive
sharp waves:
Initial positive deflaction
followed by a negative
component
Fibrilation:
Short duration potentials
(arrows) with positive and
then negative component
Muscle biopsy
• Myopathic
Muscle fiber necrosis
– Variation in size of muscle
fibers
– Necrosis + phagocytosis &
regeneration of muscle fibers
– Mild, patchy increase in
endomysial connective tissue
• Inflammation
– Endomysial & perivascular
inflammatory (mononuclear)
cells
– Macrophages & CD8+ T-cells
– Focal invasion of non-necrotic
MAC
(complement)
deposits at the
surface of the
muscle fibers
Differential diagnosis
• Myasthenia Gravis
• Electrolyte disturbances
• Metabolic, endocrine or toxic myopathies
• Muscular dystrophy
• Guillain-Barre Syndrome
Tratament
• Corticosteroids
– Good response to treatment if:
• Clinical picture: proximal or diffuse motor deficit, disease duration <1 year;
association with mialgia, cutaneous rash, connective tissue diseases
• Lab: very high serum CPK, anti Jo-1antibodies
• Biopsy: perimisial inflammation, perifascicular atrophy, necrosis and
regeneration
– Poor response to therapy if:
• Focal or asymetric motor deficit; acute or very slow form of evolution; family
history
• Lab: normal or low seric CK
• Biopsy: focal invasion of muscle fibers by inflammatory cells;
• Prednisone 1-2mg/kg/day, tapered after strength improves and CK
declines, often after 1-3 months.
TREATMENT
• Cytotoxic agents
– introduced if severe disease, relapsing disease,
inadequate steroid response or steroid induced cx’s.
– AZA or methotrexate used with steroids
– Cyclosporin, cyclophosphamide, tacrolimus and
antiTNF are alternatives.
• Intravenous immunoglobulin successful
– Child DM, esophageal dysfunction
– 1gram/kg/day
Secondary myositis
• Malignancy – lung cancer, gastric, prostate, mamary,
ovary
– Surgical intervention does not always lead to a favourable
evolution
• Drug induced:D-penicilamine; Procainamide, Hidralazine
(Lupus ± miozitis); Interferon-α; Fenitoin (inflamatory
myopaty with fever, rash, limphadenopaty and
eosinophyilia);
– Possibly related with myositis: Peniciline; Ypeca; Sulfonamide;
Levodopa; Cimetidine; Leuprolide; Propilthiouracil; Carbimazole
• Graft versus host reaction