Polyneuropathies Flashcards
classification of polyneuropathies?
pathology: axonal degeneration or demyelinating disease
time course and pattern: acute symmetrical, chronic symmetrical or multiple mononeuropathy
what is GBS (guillain-barre syndrome)?
acute ascending progressive neuropathy, 4 subtypes of which most common=
acute inflammatory demyelinating polyradiculopathy (95% of cases)
preceeding features to neurological symptoms of GBS?
those of an infection, commonly GIT e.g. campylobacter jejuni, or RT e.g. mycoplasma
other implicated organsims include HIV, EBV and CMV
what is Miller Fisher syndrome?
an overlap syndrome with GBS
inflammatory neuropathy affecting the cranial nerves, causing ophthalmoplegia, and accompanied by areflexia and ataxia but NOT weakness.
who does GBS affect?
males more commonly
bimodal presentation: 15-35yrs, and 50-75yrs are the 2 peaks
RFs for GBS?
infection-GI or resp 1-3wks prior to onsent of weakness
vaccinations
malignancy-hodgkin’s lymphoma
pregnancy-risk increases in the months after delivery
where in the NS does GBS start?
in the nerve roots
presentation of GBS?
weakness-starting 1-3wks post infection, acute symmetrical ascending starting in lower extremities, may be facial weakness, dysarthria or dysphasia, in severe cases can be resp failure
neuropathic pain e.g. backache and leg pain due to nerve root involvement
reflexes-may be reduced or absent
paraesthesia and sensory loss
ANS features-reduced sweating, reduced heat tolerance, paralytic ileus, urinary hesitancy.
features of GBS o/e of pt?
hypotonia and reduced muscle power facial weakness hypo/areflexia altered sensation or numbness AN dysfunction-HR fluctuations, arrhythmias, labile BP, variable temp resp muscle paralysis
LP results in GBS?
raised protein with no elevation in cell counts
note rise in protein may not be seen until 1-2wks post onset of weakness
most useful confirmatory test of GBS?
nerve conduction studies, should be repeated after 2 weeks if initially normal
initially may show F waves-delay in conduction due to nerve roots
how is diagnosis of GBS made?
based on clinical hx and exam.
investigations:
EMG and nerve conduction studies
LP-high protein in CSF
Abs in blood to peripheral and central nerves
anti-ganglioside and campylobacter serology
stool culture, throat swab
requirement of cardiac monitor in GBS patients?
need to monitor for ANS dysfunction:
cardiac arrhythmias
postural hypotension
HTN
why might bloods in GBS show hyponatraemia?
SIADH can be assoc. with the condition- this would be a euvolaemic hyponatraemia with high urine osmolality
most serious complication of GBS?
reps failure: occurs in 25%
need regular FVC monitoring with spirometry-QDS, if falling rapidly or FVC less than 1L then inform ITU as may need ventilation
management of GBS?
note not all patients require treatment as disease is self-limiting
general measures: close monitoring as weakness is progressive
bedside spirometry-FVC 4 hourly, ventilatory support
ECG, cardiac monitoring
nutritional support
DVT prophylaxis
analgesia
laxatives
may need urinary catheter
specific:
Iv Ig
plasmapheresis-used within 1st 2 weeks of onset
GBS complications?
acute resp failure aspiration pneumonia VTE SIADH renal failure caused by IV Ig hypercalcaemia due to immobility PAIN ileus persistent paralysis
causes of painful peripheral neuropathy?
alcoholic neuropathy-alcohol destroys nerves and reduced absorption of B vitamins
diabetic amyotrophy*
porphyria
vti B1 or B12 deficiency-subacute combined degeneration of the SC
carcinoma
causes of chronic polyneuropathy?
diabetic neuropathy
nutritional including alcohol (with or without vit B1 (thiamine) deficiency-dry beri beri (PN) and wet beri beri (HF)) and vit B12 deficiency
vascular-chronic vascular disease e.g. polyarteritis nodosa, SLE
infection-HIV, leprosy, diphtheria post infective-GBS, inflammtory-sarcoidosis, chronic inflammatory demyelinating polyneuropathy (CIDP)
metabolic-hypothyroidism, liver failure, CKD
malignancy-lung Ca, breast Ca, myeloma
idiosyncratic-drugs-isoniazid, phenytoin, gold
congenital-charcot marie tooth, friedrich’s ataxia
most common cause of peripheral neuropathy?
DM
types of neuropathy caused by diabetes mellitus?
- peripheral sensorimotor (chronic peripheral neuropathy)-sensory affected more than motor, glove and stocking distribution, loss of ankle reflexes and later knee, hands only affected in long standing neuropathy.
- acute diffuse painful (acute peripheral neuritis)-abrupt onset, burning foot pain espec. at night, unrelated to DM duration, assoc. with poor glycaemic control although may follow period of good control
- acute painful neuropathy of rapid improvement of blood glucose control-self-limiting
- diabetic amyotrophy (proximal motor)
- autonomic-cardiac, GI-gastroparesis, diarrhoea, GU-urinary hesitancy, overflow incontinence, gustatory sweating, anhidrosis
- mononeuorpathy-cranial nerves, CTS-surgery-longitudinal scar
what is diabetic amyotrophy?
main motor manifestation
form of diabetic neuropathy in which pt complains of severe pain and paraesthesia in upper legs, with weakness and muscle wasting of thigh and pelvic girdle muscles
may be asymmetrical
may be extensor plantars
us. associated with period of very poor glycaemic control, sometimes with dramatic weight loss
once good glycaemic contol achieved, pain and weakness gradually reduce
overall management considerations in diabetic neuropathy?
tight glycaemic control
regular surveillence for signs of neuropathy to allow early intervention
prevention of foot trauma
GBS prognosis?
70% complete recovery at 1 year
