Metabolic neuropathy - B12 + diabetes Flashcards
Causes ofperipheral metabolic neuropathy
diabetes mellitus, hypoglycemia, uremia, hypothyroidism, hepatic failure, polycythemia, amyloidosis, acromegaly, porphyria, disorders of lipid/glycolipid metabolism, nutritional/vitamin deficiencies, and mitochondrial disorders, among others
What fibres does diabetic neuropathy affect
Sesory A + C fibres
What anaemia does B12 deficiency present with
Megaloblastic anaemia
Who is at risk of B12 deficiency
Chronic malabsorption
History of gastric resections or bypass
Meds eg metformin and PPIs, antiepileptics
What us B12 deficiency level
<148 = probable
148-258 = possuble
What can still have if normal serum B12 levels
Pernicious anaemia
InvestigationsB12 deficiency
FBC, blood smear, serum B12, reticulocyte count
ConsiderL
MMA
Homocysteine
holotrasncobalamin
Anti intrinsic factor antibody
Treatment for B12 deficiency with neuro nvolvement
Hydroxocobalamin 1mg
IM on alternate days until no further umprovemetn
Then IM HCB 1mg IM every 2 moths
Treatment of B12 deficiency no neuro involvement
hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks
Non diet = hydroxyco. ever 2-3 months IM for life
Diet - oral cyanocobalamin 50-150 micrograms daily between meals OR twice yearly hydroxocobalamin 1mg
Foods high in vit B12
Eggs.
Foods which have been fortified with vitamin B12 (for example some soy products, and some breakfast cereals and breads) are good alternative sources to meat, eggs, and dairy products.
Meat.
Milk and other dairy products.
Salmon and cod.
First line management for neuropathic pain
One of:
Amitryptilline
Duloxetine
Gabapentin
Pregabalin
Capsaicin cream - avoid/intolerant to oral treatment
Cant have two oral meds together
Short ocourse of tramadol while qiating for referral
When refer to a specialist pain service
They have severe pain.
Their pain significantly limits their participation in daily activities (including self-care, general tasks and demands, interpersonal interactions and relationships, mobility, and sleeping).
The underlying health condition that is causing neuropathic pain has deteriorate
Features of SACD
Spasticity and up going plantars = UMN
Reduce proprioception and vibration sense - dorsal column
Normal sensation and fine touch
Bilateral symmetical lower limbs - spinal
Wha tracts are affeted in SACD
lateral corticospinal tract (motor) and dorsal columns (proprioception and vibration) - highly myelinated ones
What does length dependent/glove and stocking neuropathy suggest
SACD of cord
Degen of doral and lateral tracts of cord - mixed proprioception loss, ataxia, hyporeflexia with spasticity and upgoing plantars
Types of nerve damage
Demyelination - AI, GBS, MS, genetic
Axonopathy - chemo, compression, systemic conditions eg DM
Most to least myelinated neurons
Alpha motor
Sensory - alpha/beta - vibration/proprioception
Sensory - delta- pain/temp
Autonomic C - autonomic control
Negative sensory symptoms
Numb
Sensory loss
Proprioception loss
Temp sesnation loss
Positive sensory symptoms
hypersensitivity
Tingling
Pins and needles
Itching
Neuropathic pain
Negative motor symptoms
Weakess
Muscle wasting
Hyporeflexia
Positive motor symptoms
Fasciculations
Cramps
Autonomuc symtoms
Postural hypotension, reduced exercise tolerance
Constipation, gastroparesis
Incontinence, difficulty emptying bladder
Erctility dysfunction
Reduced hypoglycaemia awareness, sweating disturbances
What does parasympathetic NS cause
Safety - constrict pupils, sitmulates saliva, digestion, bile release, peristalsis, bladder contract
Constricts bronchi, slows HR
Vagus nerve, medulla oblongatta
What does sympathetic NS cause
Panic
Dilate pupils
Accelerated HR, dilates bronchi
Inhibits slaive and digestion, peristalsis and secretion
Stimulates glucose release - epinephrine and norepinephrone release
Relaxes bladder
Cahin of sympathetic gagnglia
Timing of neuro symptons - acute, sub acte or chronuc
Acute = hours to days BUT <4 weeks
Sub acute = days to weeks. 1-3 minths
Chronic = weeks to months >3 months
Areas in nerve damage
Focal - one peripheral nerve- trauma, swelling, compartment, infectionetc
Multifocal - more than one area eg mononeuritis multiplex
Diffuse - wide area eg bilateral
Types of neuropathy
Sensory
Motor
Sensorimotor
Autonomic
Causes of focal nerve damage
Carpal tunnel syndrome
Cubital tunnerl syndrome
Meralgia paraesthetica
Peroneal nerve injruy
Test for carpal tunnerl
Tinnels and phalens to initiate symptoms - upside down praryer and tap
Risks for carpa tunnel syndrome
- Age, pregnancy, obesity, hypothyroidism
Tingling across median distribution, severe causing weakenss
Cubital tunnel syndrome symptoms
Pain, tingling, numbness across ulnar distribution hand, grip/strength problems
What is meralgia paraeesthetica
Entrapment of laterla femoral cutaneous nerve causing pain and paraesthesia over lateral aspect of thigh - sensitive to light touch and heat
What causes meralgia paraesthetica
High weight - compression of nerve by tissue between inguinal ligament and ilium
Mangage conservatively - local anaeasthetic
What does foot drop cause
Affects - Biceps, lateral leg compartment and anterior compartment muscles
- Sensory - lateral and anterior
Abnoraml dorsiflexion, knee flexion, sensory abnormalities in lower leg
What does forehead involevment suggest about a facial palsy
LMN cause - UMN supplies both sides of forehead so would have collateral control
Which nerves are affected first in aconoapthies
Less mmyelinated - pain and temp - first
Causes of axonopathies
- B12 deficiency
- Diabetes
- Alcohol
What nerves are affeted first in demyelination
Longer more myelinated nerves 0 proprioception, motor control
Causes of demyleination
GBS
Chronic inflammatory demyelinating polyneuropathy
#Charcot-marie tooth
What antibodies see in [araneoplastic syndrome
Anti-Hu and antiCV2/CRP5 antibodies
What malignancies is paraneoplastic syndrome ass with
small cell lung cancer, B cell lymphoma, waldenstoms macroglobulinaemia
Types of paraneoplastic syndrome
Cerbeallar degneration/ataxia
Limbic encephalitis - emotions, behaviours, memory
Encephalomyelitis - inflammation of brain and spinal cord
Stiff person syndrome
Myelopathy - spinal cord
Lambert-Eaton myasthenic syndrome
Neuromyotonia
Opsoclonus-myoclonus
What is lambert eaton syndrome
This is a syndrome caused by disrupted communication between nerves and muscles. Signs and symptoms include pelvic and lower extremity muscle weakness, fatigue, difficulty swallowing, difficulty speaking, irregular eye movement, and double vision. Autonomic nervous system problems can include dry mouth and erectile dysfunction in males. Ass with lung cancer
What conditions can present as a neuropathy
MND
Myasthenia gravis
Cuada equina
Spinal cord cmpression Malignancy
What is first motor loss in peripheral neuropathies
Ankle dorsiflexion
Causes of chronic neuropathies
- Diabetes
- Alcohol excess
- B12 deficiency
- HIV
- Medication - chemo, amiodarone, isoniazid
- Autoimmune - sjrogens, lupus, sarcoidosis
- Lyme disease
- Advanced kidney disease
- Critical illness
- Myeloma/blood dyscrasias
What is charcot marie tooth
Genetic snsorimotor neuropathy - demyelinating. Begins in childhood and causes loss of proprioception and muscle power
Presentation of Charcot marie tooth
Foot drop - hammer toe deformity hooked under
Sensorimotor in hands
Distal muscle wasting
Genetics of charcot marie tooth
- Duplication of region of short arm chromosome 17 - PMP22 gene involved in myelin synthesis
- Autosomal dominant or de novo, some X linked
Investigations for sensorimotor presentation of neuropathy
- FBC - macrocytic anaemia - B12 def, chronic alcohol excess
- HbA1c - increased = new diabetes or poorly controlled
- U+Es - obvious kidney/electrolyte abnoramlities
- CRP/ESR
- B12
- TSH - hypothyroidism can cause neuro
- HIV/hepatitis
- Serum electrophoresis - myeloma
MRI brain and spine to exclude central causes
NC/EMG
