TOC  | D-Dx    

Polyneuropathy Differential -  Outlines in Clinical Medicine on Physicians' Online 2001

Polyneuropathy Mnemonic "DANG THERAPIST"


Peripheral Neuropathy

Etiologic Categorization:  Metabolic , Toxic , Immune Mediated , Vascular , Infectious , Heritable , Entrapment (compression)

Pathology of Peripheral Nerve Damage:
(Distal) Axonal Degeneration (usually toxic, vascular, metabolic) - dying back
Demyelination (usually immune/inflammatory)

Nerve Fiber Type Involvement :
Focal Neuropathies
Sensorimotor Polyneuropathy
Motor (predominantly) Polyneuropathy
Sensory (predominantly) Polyneuropathy
Autonomic Neuropathy

Laboratory Evaluations

B. Chronological Categorization of Diseases

Acute Onset Monophasic (days):
Guillain-Barre Syndrome ; Porphyric Neuropathy ; Diptheria associated polyneuropathy

Subacute Onset (weeks):
Many toxins ; Nutritional neuropathies ; Carcinomatous neuropathy ; Uremic neuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) & Refsum's Disease

Chronic (months-years):
Diabetic ; Chronic inflammatory ; Charcot-Marie-Tooth (hereditary sensorimotor neuorpathies)

C.  Focal Neuropathies

Nerve Entrapment Syndromes:
Carpal Tunnel Syndrome; Ulnar Nerve Palsy (Cubital Tunnel Syndrome) ; Brachial Plexus Lesions ; Radial Nerve Syndrome ; Tarsal Tunnel Syndrome ; Meralgia Paresthetica - lateral femoral cutaneous neuropathy ; Morton's Neuroma

Mononeuritis Multiplex:
Typically vascular etiology ; Vasculitides - including polyarteritis nodosum ; Cholesterol Emboli Syndrome ; Central Nervous System Disease causing focal deficits ; Multiple Sclerosis ; Sarcoidosis ; Central nervous system vasculitis ;

Radiculopathy (usually compression syndromes):
Cervical, Lumbar, Usually due to bone abnormalities in spine or vertebral disc disease

D. Sensorimotor Polyneuropathies (Generalized)

E. Inflammatory Neuropathies

Acute - Guillain Barre Syndrome (GBS)
CIDP - often associated with monoclonal gammopathies

Multifocal Motor Neuropathy
Weakness and muscular atrophy  & Responds to IVIg

Varicella Zoster ; Poliomyelitis ; Leprosy ; Lyme Disease

Autoimmune Etiology
Polyarteritis Nodosa
Rheumatoid Arthritis
Other Vasculitis

Gammopathy and Neuropathy

F. Predominantly Motor Neuropathies

  1. Guillain-Barre Sydnrome and CIPD
  2. Acute intermittant porphyria
  3. Lead neuropathy
  4. Heritable motor-sensory neuropathies
  5. Motor Neuron Disease (neuronopathy):
    Infantile Motor Neuron Diseases
    Poliomyelitis and Postpolio Syndrome
    Autoimmune Syndromes

G. Predominantly Sensory Polyneuropathies

Global Loss:
Diabetic polyneuropathy (see below)
Monoclonal gammopathies, dysproteinemias, paraproteinemias, cryoglobulinemia
Tabes dorsalis

Primary Loss of Pain and Thermal Sensibility
Small fiber losses
Diabetic polyneuropathy (see below)
Amyloid Deposition
Hereditary sensory neuropathies
Lepromatous leprosy

Ataxic Neuropathies
Primary loss of joint position and vibration sensation
Carcinomatous sensory neuroapthy
Sjogren Syndrome
Chemotherapeutic Agents: cisplatin
Vitamin B6 overdose
Friedreich's Ataxia
Sensory abnormalities may predominate in neuropathy with paraproteinemias

H. Diabetic Neuropathy

Complex interplay of multiple etiologic mechanisms


Mononeuropathy (multiplex)

Distal Symmetric Sensory Neuropathy:

Cranial, thoraco-abdominal, and limb neuropathies
Proximal lower limb motor neuropathy (diabetic amyotrophy) can occur
Local vascular insufficiency with nerve ischemia is most likely underlying problem
Focal inflammatory and vasculitic pathologies may occur

Diabetic Amyotrophy

Subacute Diabetic Proximal Neuropathy


Failed Therapies

I. Toxin (Drug) Associated Neuropathies

J. Chemotherapy Associated Peripheral Neuropathy

K. HIV Peripheral Polyneuropathy

Mononeuritis Multiplex (CD4>500/µL or <50/µL)

Distal Symmetrical Polyneuropathy

Inflammatory Demyelinating Polyneuropathy (CIDP related)

Non-inflammatory Neuropathy, Sensorimotor (early and late) Disease

Autonomic Nervous System

CMV Polyradiculopathy (Cauda equina syndrome)

L. Other Systemic Diseases

Peripheral Vascular Disease

Uremic Neuropathy

Thyroid Disease


M. Radicular (Nerve Root) Disease

Nerve roots pass through thecal sac to neural foramina

Narrowing of the neural foramina can lead to root dysfunction

Bone spurs, disk prolapse or herniation are the most common causes of radiculopathy

Weakness and pain are the most common presenting symptoms

Commonly Affected Regions and Weakness

Sites of Weakness