Download neuropathy classification

NEUROPATHY CLASSIFICATION
Does the patient actually have a neuropathy?
Causes of generalized weakness:
1) Motor Neuron Disease (MND)
2) Disorders of the NMJ: Myasthenia
3) Myopathy
MND:
Unknown aetiology
Affects anterior horn cells, motor nuclei of medulla & descending tracts
So: MIXTURE OF UMN & LMN signs
FASCICULATIONS – almost always present
Reflexes often present/
15-20% Get sensory Syx, rarely any objective sensory signs
Peripheral neuropathy can also be mimicked by:
1) Myelopathy
2) Syringomyelia
3) Dorsal column disorders (eg tabes dorsalis)
NB: It is important to distinguish whether the neuropathy is axonal, demyelinating, or
both. This differentiation is best achieved using nerve conduction studies (NCS) and
electromyography (EMG).
ARE SIGNS FOCAL?
Entrapment
Common sites of compression:
carpal tunnel syndrome
ulnar neuropathy at the elbow
peroneal neuropathy at fibular head
Myxedema
Rheumatoid arthritis
Amyloidosis
Acromegaly
Compressive neuropathies
Trauma
Ischemic lesions
Diabetes mellitus
Vasculitis
Leprosy
Sarcoidosis
Neoplastic infiltration or compression
ARE SIGNS MULTI-FOCAL? (suggests a mononeuritis multiplex)
Diabetes mellitus
Vasculitis
Polyarteritis nodosa
Systemic lupus erythematosus
Sjögren's syndrome
Sarcoidosis
Leprosy
HIV/AIDS
Multifocal variant of CIDP
Hereditary predisposition to pressure palsies
NB: Mononeuritis multiplex may result in sensory abnormalities in specific nerve or
nerve root distributions
Affects two or more non-contiguous peripheral nerves in separate parts of the body
Pattern of involvement is random, multifocal, and typically evolves quickly
Distal Symmetric Sensorimotor (Axonal) Polyneuropathies
NB: Most toxic and metabolic neuropathies are initially sensory and later may involve
the motor fibers
(ALSO REMEMBERED BY THE DAMMIT BICH MNEMONIC)
Endocrine diseases
Diabetes mellitus
Hypothyroidism
Acromegaly
Nutritional diseases
Alcoholism
Vitamin B12 deficiency
Folate deficiency
Whipple's disease
Postgastrectomy syndrome
Gastric restriction surgery for obesity
Thiamine deficiency
Hypophosphatemia
Critical illness polyneuropathy
Connective tissue diseases
Rheumatoid arthritis
Polyarteritis nodosa
Systemic lupus erythematosus
Churg-Strauss vasculitis
Cryoglobulinemia
Amyloidosis
Gouty neuropathy
Carcinomatous axonal sensorimotor polyneuropathy
Lymphomatous axonal sensorimotor polyneuropathy
Infectious diseases
Acquired immunodeficiency syndrome
Lyme disease
Sarcoidosis
Toxic neuropathy
Acrylamide
Carbon disulfide
Dichlorophenoxyacetic acid
Ethylene oxide
Hexacarbons
Carbon monoxide
Organophosphorus esters
Glue sniffing
Metal neuropathy
Chronic arsenic intoxication
Mercury
Gold
Thallium
Medications (see Table 8)
NB:
Motor symptoms such as weakness and wasting also commence distally
Common complaints are tripping on the toes and loss of grip strength
may have cramps or fasciculations
Polyneuropathies involve more than one type of nerve but there is usually one
(e.g. sensory or motor, large fiber or small fiber) that is predominant.
Proximal Symmetric Motor Polyneuropathies
Guillain-Barré syndrome
Chronic inflammatory demyelinating polyradiculoneuropathy
Diabetes mellitus
Porphyria
Osteosclerotic myeloma
Waldenstrom's macroglobulinemia
Monoclonal gammopathy of undetermined significance
Acute arsenic polyneuropathy
Lymphoma
Diphtheria
HIV/AIDS
Lyme disease
Hypothyroidism
Vincristine (Oncovin, Vincosar PFS) toxicity
Proximal involvement may result in difficulty climbing stairs, getting out of a
chair, lifting and swallowing, and in dysarthria
Neuropathies with cranial nerve involvement
A limited number of neuropathies involve the cranial nerves (Table 4)
Diabetes mellitus
Guillain-Barré syndrome
HIV/AIDS
Lyme disease
Sarcoidosis
Neoplastic invasion of skull base or meninges
Diphtheria
Neuropathies predominant in upper limbs
Another uncommon pattern is greater involvement of the arms than the legs
Guillain-Barré syndrome
Diabetes mellitus
Porphyria
Hereditary motor sensory neuropathy
Vitamin B12 deficiency
Hereditary amyloid neuropathy type II*
Lead neuropathy
Pure sensory neuropathies and neuronopathies
Paraneoplastic
Medications (see Table 8)
Carcinomatous sensory neuronopathy
Lymphomatous sensory neuronopathy
Sjögren's syndrome
Paraproteinemias
Nonsystemic vasculitic neuropathy
Idiopathic sensory neuronopathy
Styrene-induced peripheral neuropathy
Primary biliary cirrhosis
Crohn's disease
Chronic gluten enteropathy
Vitamin E deficiency
Hereditary sensory neuropathy types I and IV
Friedreich's ataxia
Small-fiber neuropathies (often painful)
Diabetes mellitus
Alcoholic neuropathy
Amyloidosis
AIDS
Leprosy
Hereditary
Small-fiber neuropathies often present with burning pain, lightning-like or lancinating
pain, aching, or uncomfortable paresthesias (dysesthesias). Patients may complain of
pain with innocuous stimuli such as sheets rubbing over their feet (allodynia). They
may also describe a tight, band-like sensation around the ankles or wrists. Sensory
symptoms include tingling or paresthesias, increased sensation in affected areas
(hypesthesia), and numbness or reduced sensation
Neuropathies with autonomic involvement
Diabetic neuropathy
Alcoholic neuropathy
Guillain-Barré syndrome
Paraneoplastic neuropathy
HIV/AIDS
Lymphoma
Amyloidosis
Porphyria
Thallium, arsenic, mercury toxicity
Thiamine deficiency
Vincristine (Oncovin, Vincosar PFS) toxicity
Acute pandysautonomia
Neuropathies with Abrupt/Rapid Onset
Diabetes mellitus
Cranial neuropathies
Diabetic amyotrophy
Ischemic neuropathies
Polyarteritis nodosa
Rheumatoid arthritis
Nerve compression
Hemorrhage
Swelling within a restricted anatomic compartment (e.g., anterior tibial syndrome)
Direct external compression
Penetrating wounds
Thermal injury
Iatrogenic (e.g., injection into nerves)
Drugs Causing Neuropathies
Axonal
Vincristine (Oncovin, Vincosar PFS)
Paclitaxel (Taxol)
Nitrous oxide
Colchicine (Probenecid, Col-Probenecid)
Isoniazid (Laniazid)
Hydralazine (Apresoline)
Metronidazole (Flagyl)
Pyridoxine (Nestrex, Beesix)
Didanosine (Videx)
Lithium
Alfa interferon (Roferon-A, Intron A, Alferon N)
Dapsone
Phenytoin (Dilantin)
Cimetidine (Tagamet)
Disulfiram (Antabuse)
Chloroquine (Aralen)
Ethambutol (Myambutol)
Amitriptyline (Elavil, Endep)
Demyelinating
Amiodarone (Cordarone)
Chloroquine
Suramin (Fourneau 309, Bayer 205, Germanin)
Gold
Neuronopathy
Thalidomide (Synovir)
Cisplatin (Platinol)
Pyridoxine
EXAMINATION:
Peripheral neuropathies are by definition LOWER MOTOR NEURONE lesions
Cranial Nerves:
Can provide evidence of:
Mononeuropathies
OR
Proximal involvement
NB: Motor nerves: V, VII, IX/X, XI, XII
Motor Examination
General Inspection
Fasciculations
Cramps
Trophic changes: in Severe, longstanding neuropathy
pes cavus
kyphoscoliosis
loss of hair in affected areas
ulcers
Trophic changes are most prominent in:
Diabetes
Amyloid neuropathy
Leprosy
Hereditary motor sensory neuropathy (HMSN)
with prominent sensory involvement
Hereditary sensory neuropathy
Tone: Normal or 
Power:
Pattern of weakness:
Symmetric/Assymetric
Distal/Proximal
Confined to
Particular nerve
Plexus
Nerve root level
Proximal weakness results in an inability to squat or to rise unassisted from a chair.
A bilateral foot drop may result in a steppage gait in which the patient must lift the
knees very high in order to clear the toes
Reflexes:
 or absent
Sensation:
Eg: Distal symmetric sensorimotor neuropathy
 light touch, pinprick and temperature in a stocking-and-glove distribution
Vibration and position sense are reduced in the distal legs prior to involvement of the
arms
In severe loss of position sense, there may be athetoid movement of the fingers or
arms when the eyes are closed (pseudoathetosis) or a Romberg sign
Mononeuritis Multiplex
may have sensory loss in specific nerve distributions
EXTRAS
Postural Hypotension:
Autonomic neuropathy
Respiratory rate &Vital Capacity
GBS
Lymphadneopathy/Hepato/splenomegaly
Ie Evidence of systemic disease
INITIAL Ix:
Blood glucose
HbA1C
FBE
U&E
LFT (alcoholic)
ESR
Urinalysis
B12/Folate
TFT
ECG: To look for sinus arrhythmia (lost in autonomic neuropathy)
Postural BP’s
CSF:
In myelinopathies & polyradiculopathies
High protein & < 5 WBC
GBS
CIDP
Cytology: Lymphoma
CMV DNA (AIDS)
NERVE BIOPSY:
Only helpful in very specific cases to diagnose vasculitis, leprosy, amyloid
neuropathy, leukodystrophies, sarcoidosis and, occasionally, CIDP
Sural nerve is the one most commonly selected for biopsy
Cx: infection, poor wound healing and painful dysesthesias