Diabetic neuropathy (E&M) Flashcards
Define diabetic neuropathy.
Peripheral nerve dysfunction and/or autonomic nerve dysfunction in diabetes patients by blockage of vasa vasorum.
What can diabetic neuropathy lead to?
Diabetic foot problems and ulceration (leading cause of diabetes-related hospital admissions and non-traumatic amputation)
How does diabetic neuropathy occur?
Chronic hyperglycaemia –> glycation of axon proteins –> neuropathy
Where do neuropathic ulcers usually occur in diabetic neuropathy?
Over pressure points like plantar surface of metatarsal head / hallux - painless with normal ABPI
What signs would a neuropathic ulcer from diabetic neuropathy show?
Painless with normal ABPI
What management is there for neuropathic ulcers from diabetic neuropathy?
Cushioned shoes to reduce callous formation
How can diabetic neuropathy be classified? (3)
- diffuse neuropathy - most common, distal symmetrical sensorimotor polyneuropathy (small-fibre, large-fibre or mixed), glove and stocking distribution
- mononeuropathy - isolated cranial/peripheral nerve e.g. CNIII, ulnar, median, femoral, peroneal
- radiculopathy or polyradiculopathy - radiculoplexus neuropathy, thoracic radiculopathy
What is the most common chronic complication of diabetes?
Diabetic neuropathy
What does evidence show about the origin of the pain in diabetic neuropathy?
Although pain is generated principally by peripheral nerve injury, there is evidence that the CNS may play a significant role in disinhibition and amplification of pain - most effective drugs in treating painful diabetic neuropathy are centrally-acting (pregabalin, duloxetine, tapentadol)
What are the clinical features of peripheral neuropathy (diabetic neuropathy)? (6)
- peripheral pain - burning/sticking/aching, worse at night
- large-fibre: tight, band-feeling
- small-fibre: burning
- loss of peripheral sensation - glove and stocking distribution
- peripheral dysesthesia - burning sensation in feet
- reduced/absent ankle reflexes
- peripheral painless injuries at pressure points
- may be asymptomatic
How does mononeuropathy present (diabetic neuropathy)?
Sudden motor loss e.g. wrist drop, CN III palsy (down and out eye)
How do automatic symptoms of diabetic neuropathy present? (7)
- resting tachycardia
- urinary frequency/urgency/nocturia/incontinence/hesitancy/weak stream/retention
- erectile dysfunction
- constipation
- difficulty swallowing
- postural hypotension
- gastroparesis - N&V, bloating, loss of appetite, early satiety (treated with metoclopramide - prokinetic that improves gastric emptying)
What can we give for gastroparesis in diabetic neuropathy?
Metoclopramide - prokinetic that improves gastric emptying
What other problem does autonomic neuropathy in diabetic neuropathy cause?
Impaired hypoglycaemia awareness
What are the clinical features of diabetic foot disease? (4)
- ulceration
- dry skin
- reduced subcutaneous tissue
- Charcot’s arthropathy (erythematous, oedema, calor)
How can you classify diabetic foot disease? (4)
- grade 1: no systemic signs, well-demarcated, warm surroundings
- grade 2: local swelling/induration, erythema<2cm, local pain, warmth and purulent discharge
- grade 3: abscess, osteomyelitis (deep or chronic wound), septic arthritis, fasciitis
- grade 4: SIRS (septic), apyrexia, pulse>90, RR>20
What is a fetid foot (diabetic neuropathy)?
Chronic soft tissue and bone infection causes a foul exudate and usually requires extensive surgical debridement and/or amputation
What might you find on examination in peripheral neuropathy (diabetic neuropathy)? (5)
- peripheral loss of sensation
- peripheral dysesthesia, weakness
- gait ataxia
- reduced/absent ankle reflexes
- painless injuries
What are some risk factors for diabetic neuropathy? (9)
- poorly controlled hyperglycaemia
- prolonged duration of diabetes (>10y)
- older age (>70y)
- tall stature
- hypertension
- dyslipidaemia with elevated triglycerides
- CVD risk factors
- obesity
- smoking
How is diabetic neuropathy usually diagnosed?
Clinical diagnosis
What bloods do we do for diabetic neuropathy? (3)
- fasting blood glucose
- HbA1c (correlates with degree of glycaemic control)
- serum lipid profile
What blood tests do we do as exclusions for diabetic neuropathy? (7)
- TSH
- vitamin B12
- electrolytes
- U&Es
- LFTs
- FBC
- ESR
How do we test sensation in diabetic neuropathy? (3)
- 10g monofilament
- tuning fork (decreased vibration sense)
- pinprick assessment (decreased sensation)
What do nerve conduction studies show in diabetic neuropathy? (5)
- slowing of conduction
- decreased amplitude of sensory nerve action potentials
- decreased amplitude of compound muscle action potentials
- relative preservation of proximal conduction velocities
- evidence of fibrillation potentials
What are some differential diagnoses for diabetic neuropathy (treatable causes of neuropathies)? (8)
- toxins (alcohol)
- neurotoxic medications (chemotherapy)
- vitamin B12 deficiency (especially if on metformin or PPI)
- hypothyroidism
- renal disease, monoclonal gammopathy
- infections (HIV)
- chronic inflammatory demyelinating neuropathy
- inherited neuropathies and vasculitis
What do we need to optimise to manage diabetic neuropathy?
Glycaemic control
What is the 1st-line management for peripheral diabetic neuropathy without pain?
- glycaemic control and supportive measures
- diabetic foot care
What is 1st-line (to 5th-line) for painful diabetic neuropathy?
- 1st line: pregabalin / gabapentin / duloxetine
- 2nd line: amitriptyline / venlafaxine (antidepressant / Na+ channel blocker)
- 3rd line: topical capsaicin
- 4th line: TENS, PENS or acupuncture
- 5th line: spinal cord stimulation
Which patients do we avoid amitriptyline in (diabetic neuropathy)?
Patients with BPH as it can cause urinary retention
How do we manage automatic neuropathy in diabetic neuropathy? (5)
- orthostatic hypotension - midodrine –> ephedrine –> fludrocortisone
- gastroparesis - domperidone, metoclopramide, diet
- diarrhoea - metronidazole, octreotide
- bladder dysfunction - bethanechol
- erectile dysfunction - sildenafil (PDE-5 inhibitor)
How do we manage diabetic foot disease? (4)
- mild (S. aureus or Streptococci) - flucloxacillin, co-amoxiclav
- moderate to severe (gram +ve, -ve and obligate anaerobes) - ceftriaxone, flucloxacillin and metronidazole
- P. aeruginosa - usually not necessary to treat
- suspected MRSA - involve microbiology
What are some complications of diabetic neuropathy? (7)
- foot wounds/ulcers
- wound infection/gangrene
- amputation
- silent MI (impaired heart rate variability)
- depression
- death
- Charcot foot
What is Charcot foot (complication of diabetic neuropathy)? (4)
- loss of protective sensation in foot
- increased blood flow to foot - due to autonomic neuropathy –> bone loss and weak bones susceptible to injury
- unrecognised trauma
- Charcot arthropathy - erythematous, oedema, calor
Describe the prognosis of diabetic neuropathy.
Depends on how well diabetes is managed - improvement in BGC control may slow progression but recovery may be very slow
