LMN Flashcards
Name the 4 possible anatomical sites of a LMN lesion
Anterior horn cell
Peripheral or cranial nerve
Neuromuscular junction
Muscle
Classic distribution of weakness in peripheral neuropathy
Distal
Classic distribution of weakness in myopathies
Proximal
Classic distribution of weakness in Myasthenia Gravis (4)
Eyelid, ocular, bulbar and proximal weakness
Classic distribution of weakness in radiculopathy
Localised weakness
Classic distribution of weakness in mononeuropathy
Localised weakness
Which enzyme may be raised in LMN lesion
Creatine phosphokinase enzyme
Examples of anterior horn cell disease (3)
Amyotrophic lateral sclerosis (motor neurone disease)
Poliomyelitis
Cervical spondylosis eg cervical spinal stenosis, spinal muscular atrophy
Diagnostic criteria for ALS positive (3) and negative (4) signs
Presence of: LMN and UMN signs! Progression (In a large number of areas confirm. >3 eg brainstem, cervical, thoracic....) Absence of: Sensory signs Sphincter dysfunction Parkinson's Alzheimer
Where is the lesion in motor neurone disease
LMN: anterior horn cell
3 Pathopneumonic signs of peripheral neuropathy
Absent or decreased reflexes
Distal weakness
NB: glove and stocking sensory loss
Onset of GBS
Acute - 4 weeks peak
CSF findings in GBS
Raised protein
Precipitating event for GBS?
Resp/ GIT viral infection especially campylobacter jejuni and after vaccinations
Complications of GBS that must be monitored (4)
Respiratory failure
Problems with swallowing and aspiration
DVT and pulmonary embolism
Autonomic complications eg arrhythmia, changes in BP
6 Common examples of mononeuropathies
Bell’s palsy (cnvii)
Carpal tunnel syndrome (median nerve)
Saturday night palsy (radial nerve)
Cubital tunnel syndrome (ulnar nerve)
Meralgia paraesthetica (lat cut n of thigh)
Deep peroneal nerve compression behind head fibula
Name 2 positive tests in carpal tunnel syndrome
Tinel sign
Phalen test
Name the mononeuropathy seen in picture 5.
Saturday night palsy: radial nerve
How will compression of the deep peroneal nerve present?
Loss of sensation in triangular area between big and second toe, weak tibialis ant, extensor hallucis and extensor digitorum brevis (foot drop)
How can peripheral neuropathy be subdivided by the nerve conduction velocities?
Axonal - relatively normal
Demyelinating-slowed
4 clinical phenotypes of peripheral neuropathy
- Symmetrical peripheral neuropathy
- Mononeuropathy
- Mononeuritis multiplex
- Autonomic neuropathy
Name common causes of axonal neuropathy - type periph neuropathy (4)
Alcohol associated
Thiamin deficiency (b1)
Uremia
Drugs: gold, isoniazide, vincristine (chemo), nitrofurantoin (anti-bac for bladder infec)
Name Common causes of demyelinating neuropathy - type periph neuropathy (4)
Guillan Barre Syndrome
Chronic inflammatory demyelinating polyradiculopathy (CIDP)
Charcot-marie - tooth disease (hereditary motor and sensory neuropathy type 1)
DM
Name common causes of a predominantly motor neuropathy (4)
GBS
Porphyria
Lead poisoning
Hereditary motor and sensory neuropathy type 1 and 2
Name causes of predominantly sensory neuropathy (4)
DM
Alcohol-associated
Drugs -isoniazide, allopurinol ( rx gout), statins
Arsenic
Causes of symmetric peripheral neuropathy (4)
DM
GBS
Alcohol
Uremia
What is CIDP? (3)
Chronic inflammatory demyelinating polyradiculopathy
Related to GBS, very similar presentation, except no preceding infection
Autoimmune demyelinating
Which radiculopathies are most common? (2)
L5 and S1
What are the features of an L5 radiculopathy? (6)
Neuralgic sharp shooting pains from back to post thigh, lat lower leg, dorsum foot.
Sensory disturbances over lateral lower leg, dorsal foot, big toe.
Laséque test (straight leg raise) elicit pain in back ipsilateral, contralateral also plus spread over post thigh or neuralgic pain in L5 distrib.
Can’t walk on heels
Foot drop ipsilateral
Weakness: extensor hallucis, tibialis ant and post, glut med and max
What are the features of an s1 radiculopathy? (5)
- Neuralgic pain from back to post thigh, lower leg, Lat foot and small toe.
- lasegue test positive: lie down and raise one leg. <45’: back pain both sides, may spread to post thigh and in distrib of s1 root.
- walk on toes - heel sags on side of radiculopathy
- ankle reflex decreased or absent
- weak: plantarflex toes and foot, hamstring, glut max
Name diseases of the NMJ
Myasthenia Gravis
Lambert Eaton Syndrome
(Botulism)
(Organophosphate poisoning)
Characteristics of Myasthenia Gravis clinical (5)
- Fatigueability! Worse with exertion.
- 90% ocular and bulbar muscle involvement!
- Positive eyelid fatigue test, arms, legs.
- No sensory deficit
- mestinon test:pyridostigmine/neostigmine
Investigations signs in Myasthenia Gravis (4)
- Raised acetylcholine receptor antibody titer!
- Decremental response of motor action potentials with repetitive stimulation at 2 Hz
- Normal creatine phosphokinase
- increased “jitter” on single fibre EMG
Lambert Eaton syndromes / myasthenia syndrome clinical features (3)
Weakness of proximal muscles LL (quads)
Decreased absent reflexes
Paradoxically gets better with exertion.
Autonomic involvement: dry mouth, impotence
Characteristics of myopathies (4)
Proximal weakness
Myotonia
Positive family history
Raised creative phosphokinase
Muscle dystrophies characteristics (3)
Hereditary
Weakness slowly progressive
Muscles involved selectively
Clinical sign of Duchenne muscular dystrophy (6)
Hypertrophy calves Gower's sign Onset 3-5 years age boy Cardiomyopathy Mental retard 1/3 Wheelchair bound by 12 y
Duchenne’s muscular dystrophy Lab features (3)
VERY high CK (several thousands)
Absence of dystrophin protein on muscle biopsy
Xp21 chromosome dysfunction with x-linked inheritance.
Clinical features of facioscapulohumeral muscle dystrophy (3)
Facial weak
High riding scapulae
Weakness shoulder - trapezius, serratus ant, pec ant
Inheritance of facioscapulohumeral muscle dystrophy
Aut dom on chromosome 4q35
Myotonic dystrophy clin signs (8)
Distal muscles Eyelid, masticatory, facial, neck flexor, cardiac muscles Cataracts Frontal alopecia Mental retard Myotonia!
Inheritance of myotonic dystrophy
Autosomal dominant
Chromosome 19 and 3
Polymyositis characteristics clin (4)
Sub- acute onset of proximal weak 3-6 months
Muscle pains and tender
Arthralgia
Dysphagia
Polymyositis lab characteristics (3)
Raised creatine phosphokinase
Muscle biopsy: muscle fibre necrosis with lymphocyte and plasma cell infiltrates
EMG: fibrillation potentials, small short-duration polyphasic myopathic motor units
Inclusion body myositis clin features (3)
Both quads muscles weak
Muscles of swallowing
Wrist and finger flexor muscles
How does treatment of inclusion body myositis differ to that of polymyositis
Polymyositis treated with steroids
Inclusion body myositis resistant to immune modulating therapy
Treatment Bell’s palsy? (3)
- steroids
- antiviral (acyclovir)
- tape eyes/natural tears
Name 6 features LMN lesion
- Marked atrophy
- fasciculation’s
- decreased tone
- variable patterns of weakness:individual or groups of muscles
- reflexes decreased/absent
- flexor plantar response (normal) or absent
Myopathy vs neuropathy? (4)
- Proximal vs distal weakness
- reflexes normal early on vs weak or absent
- sensory symptoms absent vs present
- CK elevated vs normal
Define guillain Barre syndrome
Acute (<4 weeks) inflammatory demyelinating mono-phasic auto-immune polyneuropathy
Lesion of spinal root
Name 6 variants guillain Barre syndrome
- Acute inflammatory demyelinating polyradiculOneuropathy (aidp) = most common
- acute motor axonal neuropathy (aman) ( pure motor form)
- acute motor sensory axonal neuropathy (amsan)
- Miller fisher syndrome: ophthalmoplegia+ ataxia +arreflexia
- bickerstaffs brainstem encephalitis
- Acute pan-autonomic neuropathy: rare
Name most common variant guillain Barre syndrome
AIDP: acute inflammatory demyelinating polyradiculopathy
What is Miller fisher syndrome and what is it characterised by? (4)
Variant of guillain Barre syndrome
- ophthalmoplegia
- ataxia
- areflexia
Diagnosis guillain Barre syndrome? (8)
AIDP
Required criteria = asbury criteria
- areflexiA
- increasing weakness 2 or more limbs due to neuropathy: ascending, symmetrical weakness. Lower limbs first. Proximal muscles first. Can also affect trunk, bulbar, resp muscles
- duration <4 weeks
- preclude other causes: porphyria mimics!
Supportive criteria
- afebrile
- involvement: mild sensory; facial or other cranial nerve involvement, neck flexion weakness; symmetrical progression
- demyelinating electrophysiological evidence: conduction block, focal slowing motor > sensory, decreased F wave, sural nerve sparing
- protein in CSF
Management guillain Barre syndrome? (4)
AIDP
- Assistive: analgesia with neuropathic agents (amitriptylline, gabapentin, ) ; airway; autonomic (prone to arrhythmia ); anti-thrombotic
- iv ig 0,4 G lig/day for 5-days
- do not give steroids
- plasma exchange plex via central line as alternative to iv ig , 5 sessions on alternating days