Peripheral neuropathy DDx

Overview

Diseases that affect the the peripheral nerves, either motor or sensory. Important subgroups for differential diagnosis are: predominately motor, painful peripheral neuropathies and mononeuritis multiplex

Mononeuritis multiplex is a painful, asymmetrical, asynchronous sensory and motor peripheral neuropathy involving isolated damage to at least 2 separate nerve areas that can be in random areas of the body.

Causes

Peripheral neuropathies

“DAM IT BICH”

• drugs and toxins – e.g. heavy metals, isoniazid, vincristine, phenytoin, nitrofurantoin, cis-platinum, amiodarone, larges of vitamin B6,
• alcohol and amyloid
• metabolic – e.g. DM (30%), acromegaly, hypothyroidism
• infectious/post- – e.g. Lyme, diptheria, GBS
• tumor – e.g. lung CA
• B12, B1, B5 or B6 deficiency
• idiopathic (30%)
• CTD or vasculitis, e.g. SLE, PAN
• hereditary (30%)

or the alternative “DAM IT BITCH”:

• D Drugs and chemicals (Pb, phenytoin, metronidazole, amiodarone, hydralazine, vincristine, isoniazid, organic solvents, sulphonamides, nitrofurantoin, CO, OPs).
• A alcohol (with or without Thiamine deficiency)
• M metabolic (diabetes, hypoglycemia, uraemia)
• I infection (HIV, leprosy, lyme, diptheria, syphilis) or post infectious (GBS)
• T tumour (paraneoplastic phenomenon – lung, lymphoma, myeloma)
• B B12 & other vitamin deficiency states, as well as pyridoxine excess
• I idiopathic and infiltrative (e.g. amyloidosis)
• T toxins (botulism, ciguatera, Tetrodotoxin, Saxitoxin, BRO, tick paralysis)
• C connective tissue diseases (e.g. SLE, PAN, RhA) and congenital (e.g. CMT)
• H Hypothyroidism

Predominately motor peripheral neuropathy

• Guillain-Barré syndrome, chronic inflammatory polyradiculoneuropathy
• Hereditary motor and sensory neuropathy
• Diabetes mellitus
• Others-e.g. acute intermittent porphyria, lead poisoning, diphtheria, multifocal conduction block neuropathy

Painful peripheral neuropathy

“BADCAP”

• Diabetes mellitus
• Alcohol
• Vitamin B1 or B12 deficiency
• Carcinoma
• Porphyria
• Arsenic or thallium poisoning

Mononeuritis multiplex

Acute

• Diabetes mellitus
• Polyarteritis nodosum
• Connective tissue diseases, e.g. SLE, Rheumatoid arthritis

Chronic

• multiple compressive neuropathies
• sarcoidosis
• acromegaly
• leprosy
• Lyme disease
• idiopathic

Polyneuropathies with autonomic involvement

These are the common ones:

• diabetes mellitus
• amyloidosis
• Guillain-Barre Syndrome
• Paraneoplastic neuropathy (usually lung cancer)
• Sogren’s syndrome-associated neuropathy

References and Links

Journal Articles and Textbooks

• Burns JM, Mauermann ML, Burns TM. An easy approach to evaluating peripheral neuropathy. J Fam Pract. 2006 Oct;55(10):853-61. Review. PubMed PMID: 17014750. [Free Full Text]
• Talley NJ, O’Connor S. Clinical Examination: A Systematic Guide to Physical Diagnosis. MacLennan and Petty. 3rd edition, 1998.

CCC Differential Diagnosis Series
NEURO	Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision
RESP	Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement
CVS	Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction
GIT	Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage
GUT	Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency,
MSK	Arthritis, Shoulder pain, Wasting of the small muscles of the hand
DERM	Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans
ENDO	Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss
HAEM	Splenomegaly
PAEDS	Floppy infant
MISC	Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest
IMAGING	CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR, ABDO: Gas on abdominal X-ray, Kidney mass, BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly, OTHER: Pseudofracture on X-Ray,
LABS	LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia,  HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia,  ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis, Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes

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