Peripheral polyneuropathy Flashcards
Sensory findings in peripheral polyneuropathy
Bilateral, symmetrical
Glove and stocking distribution: length dependent
Reduced tendon reflexes (loss of ankle jerks in DM)
Signs of trauma or joint deformity (Charcot’s joints)
Loss of proprioception - positive Romberg’s test
Motor findings in peripheral polyneuropathy
Bilateral, symmetrical
LMN weakness: wasting, fasciculations, reduced tone, hyporeflexia
Completion of neurone exam in peripheral neuropathy
Review drug chart
Dipstick for glucose
Gait + Romberg test
Cranial nerve exam
Causes of peripheral polyneuropathy
Mainly sensory: DM EtOH B12 deficiency CRF (uraemia) and Ca (paraneoplastic) Vasculitis Drugs e.g. isoniazid, vincristine Mainly motor: HMSN/CMT Paraneoplastic (Ca lung, RCC) Lead poisoning Acute - GBS and botulinum
Specific history for peripheral polyneuropathy
Time course
Precise symptoms: ataxia - B12, painful dysesthesia - EtOH, DM
Associated events: D+V - GBS, weight loss - cancer, arthralgia, CTD.
Travel, EtOH, drugs.
Investigations for peripheral polyneuropathy
Dipstick: glucose Bloods: DM (glucose, HbA1C), EtOH (FBC ± film, LFTs, GGT), CRF (U+E), B12, folate, vasculitis (ESR, ANA, ANCA), thyroid disease (TFTs). Imaging: CXR for paraneoplastic. Nerve conduction studies Electromyography Genetic (PMP22 gene in CMT) Nerve biopsy
Nerve conduction studies interpretation
Demyelination - reduced conduction speed, axonal degeneration - reduced conduction amplitude
General management of peripheral polyneuropathy
MDT
Foot care and careful shoe choice
Splinting joints can prevent contractures
Specific medical management for peripheral polyneuropathy
Optimise glycemic control (DCCT, UKPDS trials)
Replace nutritional deficiencies
Avoid EtOH or other precipitants
Vasculitis: steroids/immunosuppressants
Neuropathic pain: amitriptyline, gabapentin
GBS: IVIg
Signs on inspection for diabetic neuropathy
Finger-pricks from BM monitoring
Peripheral vascular disease
Charcot joints
Bilateral loss of ankle jerks (sensory neuropathy)
Mononeuritis multiplex - foot drop
Distal sensory loss in stocking distribution
Completing diabetic neuropathy exam
Examine the fundi
Examine the upper limbs and cranial nerves: sensory neuropathy, mono neuritis multiplex (CN3, CN6, ulnar nerve).
Urine dip: glucose, proteinuria.
Specific history for diabetic neuropathy
Pain, especially at night
Glycaemic control
Complications of insulin
Other micro- and macro-vascular complications
Pathophysiology of diabetic neuropathy
Metabolic: glycosylation, ROS, sorbitol accumulation
Ischaemia: loss of vasa nervorum
Investigations for diabetic neuropathy
Urine: glucose, ACR
Blood: glucose, HbA1c, U+E
Management of diabetic neuropathy
MDT
Good glycemic control
Amitriptyline, gabapentin
Capsaicin cream
Describe femoral neuropathy
AKA diabetic amyotrophy AKA proximal diabetic neuropathy.
Painful asymmetric weakness and wasting of quadriceps with loss of knee jerks.
Diagnose by nerve conduction studies and electromyography.
Features of autonomic neuropathy
Postural hypotension - treat with fludrocortisone
Gastroparesis - early satiety, GORD, bloating
Diarrhoea - treat with codeine phosphate
Urinary retention
Erectile dysfunction
Synonyms to Charcot-Marie-Tooth syndrome
Hereditary Motor and Sensory Neuropathy (HMSN), peroneal muscle atrophy
Charcot-Marie-Tooth syndrome findings on examination
Inspection:
Pes cavus
Symmetrical distal muscle wasting - claw hand, champagne bottle leg
Thickened nerves: especially common peroneal around fibula
Motor:
High-stepping gait (foot drop)
Weak foot and toe dorsiflexion
Absent ankle jerks
Sensory:
Variable loss of sensation in a stocking distribution
Specific history in Charcot-Marie-Tooth syndrome
Family Hx
Pathophysiology of commonest types of CMT
CMT1 (=HMSN1) is the commonest form
Demyelinating
AD mutation in peripheral myelin protein 22 gene (PMP22)
CMT2 (=HMSN2) is the second most common.
Axonal degeneration, also autosomal dominant.
Investigations for CMT
Nerve conduction studies
Genetic testing
Differentiating between CMT1 and CMT2 with nerve conduction studies
CMT1 is demyelinating - nerve conduction studies will show reduced velocity
CMT2 is axonal degeneration - nerve conduction studies will show reduced amplitude
Management of CMT
MDT
Foot care and careful shoe selection
Orthoses e.g. ankle braces
