Neuro Paces Flashcards
How to test upper limb myotomes and peripheral nerve
C5- shoulder abduction
C6- elbow flexion and wrist extension
C7- elbow extension
C8- thumb extension
T1- finger abduction
Median - flexion and pronation
Ulnar- flexion of ring and little finger DIP, intrinsic muscles of the hand
Radial- extension
How to differentiate ulnar nerve palsy from C8/T1 pathology
Abductor pollicis brevis would be weak in a C8-T1 lesion, it is supplied by the median nerve
Normal sensation in T1 if ulnar lesion
What are the signs of an ulnar nerve palsy?
- Relevant scar
- ‘Ulnar claw’ Extension at 4th and 5th metacarpal phalangeal joint and flexion at distal joint
- Wasting of small muscles of the hand
- Weak abduction of fingers
- Normal strength in abductor pollicis brevis
- Altered sensation in ulnar distribution
Types of diabetic neuropathy
- Distal symmetric polyneuropathy - progressive distal sensory loss in a glove and stocking distribution results in axonal loss in nerve conduction studies, motor involvement in severe cases
- Autonomic neuropathy- postural hypotension, gastroparesis, gustatory sweating, resting tachycardia
- Diabetic amyotrophy- microvasculitis presents with asymmetric pain then weakness in the proximal leg along with weight loss
Causes of peripheral neuropathy
1) Metabolic
- Diabetes (chronic, sensory predominant, length dependent)
- B12, B1, B6 deficiency
- Uraemia
- Hypothyroidism
2) Infective
- HIV (distal sensory, often painful)
- Lyme disease
3) Immune
- CIDP (relapsing course, often not length dependent)
- Paraprotrinaemic (myeloma or MGUS)
- Connective tissue disease (RA, sjogren, SLE, sarcoidosis)
- paraneoplastic (most commonly lung ca
- GBS
4) Genetic
- Charcot Marie Tooth
- Acute intermittent porphyria
5) Toxic
- isoniazid
- pyridoxine
- lead
- chemotherapy
Investigating diabetic neuropathy
Nerve conduction studies show a sensory axonal loss with reduced or absent sensory nerve action potentials in a length- dependent manner with the legs being most affected
Management of diabetic neuropathy
Optimise diabetes control
Foot care
Pain management
Postural hypotension managed with fludrocortisone
GI symptoms with prokinetics and antiemetics
Clinic signs of hereditary sensory motor neuropathy (Charcot Marie Tooth)
Wasting of distal lower limb muscles with preservation of the thigh muscle bulk
Pes cavus
Stocking distribution sensory loss
High steppage gait due to foot drop and stamping due to loss of proprioception
Wasting of hand muscles
Palpable lateral popliteal nerve
What causes hereditary sensory motor neuropathy
Most common types are I (demyelinating) and II (axonal) therefore nerve conduction studies are useful
Autosomal dominant inheritance (test for PMP22 mutations in HSMN I)
Tests for HSMN
Nerve conduction studies
Genetic testing
Management of HSMN
Physiotherapist/ occupational therapist
Orthotics
Genetic counselling
Causes of predominantly sensory peripheral neuropathy
DM
Alcohol
Drugs eg. Isoniazid and vincristine
Vitamin deficiencies - b12 and b1
Causes of predominantly motor peripheral neuropathy
Guillain barre and botulism present acutely
Lead toxicity
Porphyria
HSMN
Causes of mononeuritis multiplex
DM
Connective tissue disease eg. SLE and RA
Vasculitis
HIV
Malignancy
What causes a central scotoma?
Optic nerve disease eg. Optic neuritis
Affects ipsilateral side
What causes a bitemporal haemianopia?
Chiasmal lesion
Upper fields worse affected in pituitary tumours
Lower fields worse affected in craniopharynhiomas
What causes a homonomous superior quadrantanopia?
Temporal lobe lesion
What causes a homonymous inferior quadrantanopia?
Parietal lobe lesion
What causes a homonymous hemianopia?
Post chiasmal lesion, the more congruous the more posterior the lesion is
A posterior cerebral stroke can cause macular sparing due to dual blood supply
What is the Pathophysiology of MS?
BBB is more permeable to immune cellls. T cells enter the CNS. T cells attack the myelin sheath leading to inflammation.
How does MS present?
Sensory- Parasthesia, hypoaesthesia, pain, MS hugs
Optic neuritis- diminished visual acuity, decreased colour perception, periorbital pain preceding vision loss
Weakness- exercised induced weakness is characteristic, UMN signs
Spasticity
Bladder dysfunction
Constipation
Sexual dysfunction
Uthoff’s phenomenon- symptoms worse after hot bath
Lhermitte’s sign- lightening pains down the spine on neck flexion due to cervical cord plaques
Disease course of MS
Relapsing remitting
Secondary progressive
Primary progressive
Differentials for MS
Inflammatory conditions- neuromyelitis optica, shortens, ADEM, CNS lupus/vasculitis
Infection - syphilis, Lyme disease, HIV
Metabolic- B12 deficiency, mitochondrial disease
Diagnosis and investigation of MS
Need to prove dissemination of disease activity in time and space.
1. Clinical history
2. MRI
3. Unpaired oligoclonal bands in the CSF (not specific for MS, occur in 85% of cases)
Management of MS
Multidisciplinary approach
DMARDs:
- interferon B and glariramer reduce relapse rate but don’t affect prognosis, they are 1st line for mild disease
- mabs offer greater benefit, used if 2 disabling relapses in 1 year
Stem cell transplantation
Management of acute MS flare
Rule out psueudo relapse (ie. Worsening of existing symptoms by underlying stressor eg. Infection
Methyl pred
Management of MS complications
Baclofen for spasticity
Anti- depressants
Neuropathic analgesics
Antichoniergics/self catherisation for bladder symptoms
How is MS affected by pregnancy?
Reduced relapse rate in pregnancy
Increased risk of relapse in postpartum
What causes MS?
Both genetic (HLA-DR2 and interleukin 2&7 receptors) + environmental factors (EBV)
Clinical signs of cerebellar syndrome
Dysdiadochokinesis
Ataxia
Nystagmus
Intention tremor
Scanning dysarthria
Hypotonia/ hyporeflexia
How does the direction of nystagmus help determine side on the lesion?
The fast phase of the nystagmus is towards the side of the lesion and is maximal on looking towards the lesion
Causes of cerebellar syndrome
Stroke
Paraneoplastic
Alcoholic cerebellar degeneration
Multiple sclerosis
SOL in the posterior fossa
Fredrich’s ataxia and ataxia telangiectasia
Phenytoin toxicity
Hypothyroidism
Clinical signs pointing to different causes of cerebellar syndrome
Internuclear ophthalmoplegia, spasticity, younger female = MS
Optic atrophy = MS or Fredrichs ataxia
Clubbing/ cigarette fingers, radiotherapy burn = bronchial carcinoma
Liver disease = alcohol excess
Neuropathy = alcohol or fredrichs ataxia
Gingival hypertrophy = phenytoin
What happens in internuclear ophthalmoplegia?
The side of the brain affected is the same side as the eye that cannot adduct. Eg. A left sided lesion will result in the left eye not addicting when looking right and the right eye will have nystagmus.
Caused by a lesion affecting the medial longitudinal fasciculus (a heavily myelinated tract).
How can you differentiate sensory ataxia from cerebella ataxia
Sensory ataxia - impaired sensation particularly vibration and joint position, pseudoathetosis, able to finger nose test with eyes open but not with eyes closed
Cerebella ataxia - other cerebellar signs
How does ALS present?
UMN and LMN signs
Upper limb weakness> lower limb weakness
Fasciculations
Asymmetrical
Slurred speech
Dysphagia/dysarthria
How does progressive bulbar palsy present?
Facial muscle weakness
Dysphagia
Dysarthria
Emotional lability
Upper and lower weakness
How does progressive muscular atrophy present
LMN
Muscle atrophy
Fasciculations
Muscle weakness
Best prognosis
How does primary lateral sclerosis present?
Spastic weakness of the limbs
Spastic dysarthria
Dysphagia
Aggressive course
How is a case of suspected MND investigated?
Blood tests inc. vitamin levels, CK assay and anti-GM1 antibodies
EMG showing Fasciculations
Nerve conduction studies
Serum protein electrophoresis
Muscle biopsy
MRI - so assess for other key differentials
What is Kennedy disease?
X linked spinobulbar muscular atrophy
Associated with a CAG trinucleotide repeat mutation
Lower motor neurone disease
Causes progressive weakness and wasting of the limb and bulbar muscles with an absence of spasticity and slight sensory neuropathy
Associated with gynaecomastia and reduced fertility
Causes of generalised wasting of hand muscles
Anterior horn cell
- MND
- syringomelia
- cervical cord compression
- polio
Brachial plexus
- cervical rib
- Pancoast’s tumour
- trauma
Peripheral nerve
- combined median and ulnar nerve lesion
- peripheral neuropathy
Muscle
- disuse atrophy
What are Fasciculations?
Caused by axonal loss resulting in the surviving axons recruiting and innerating more myofibrils than usual resulting in large motor units
Seen commonly in MND and syringomelia
Clinical signs of myelopathy
UMN signs: hypertonia, ankle clonus, generalised weakness, hyperreflexia with up going plantars, hyperreflexia
How to differentiate cause of myelopathy
Sensory level which might suggest where the lesion is
Scars or spinal deformity
Signs of MS
Bladder symptoms/catheter
Suggest testing anal tone
Causes of myelopathy
MS
Spinal cord compression
Trauma
MND
Anterior spinal cord thrombosis
Syringomelia
Hereditary spastic paraplegia
Subacute combined degeneration of the cord (absent reflexes with upgoing plantars)
Lower limb myotomes
Hip flexion - L2/3
Knee extension - L3/4
Foot dorsiflexion- L4/5
Knee flexion - L5/S1
Foot plantarflexion - S1/2
What are the key features of Kennedy disease?
Slow progression
Perioral Fasciculations
Associated with gynaecomastia and reduced fertility
How does poliomyelitis present?
Acute flaccid paralysis, typically unilateral.
Reduced reflexes and atrophy of the affected limb.
GI prodrome.
What is post- poliomyelitis syndrome?
Weakness, fatigue and wasting of affecting muscles