Chapter 196: Peripheral Neuropathies, Including Guillain-Barré Syndrome

Chapter 196: Peripheral Neuropathies, Including Guillain-Barré Syndrome is a topic covered in the Harrison's Manual of Medicine.

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Approach to the patient: Peripheral Neuropathy

Peripheral neuropathy (PN) refers to a peripheral nerve disorder of any cause. Nerve involvement may be single (mononeuropathy) or multiple (polyneuropathy); pathology may be axonal or demyelinating. An approach to pts with suspected neuropathy appears in Fig. 196-1.

Seven initial questions:

  1. What systems are involved? Determine if symptoms and signs are predominantly motor, sensory, autonomic, or a combination of these. If only weakness is present without sensory or autonomic dysfunction, consider a motor neuropathy, neuromuscular junction disorder, or myopathy; myopathies usually have a proximal, symmetric pattern of weakness.
  2. What is the distribution of weakness? Polyneuropathy involves widespread and often symmetric dysfunction of the peripheral nerves that is usually distal more than proximal; mononeuropathy involves a single nerve, usually due to trauma or compression; multiple mononeuropathies (mononeuropathy multiplex) can be a result of multiple entrapments, vasculitis, or infiltration.
  3. What is the nature of the sensory involvement? Temperature loss or burning/stabbing pain suggests small fiber involvement. Vibratory or proprioceptive loss implicates large fibers.
  4. Is there evidence of upper motor neuron involvement? The most common cause is combined system degeneration with B12 deficiency, but should also consider copper deficiency, HIV infection, severe hepatic disease, and adrenomyeloneuropathy.
  5. What is the temporal evolution? Most neuropathies are insidious and slowly progressive. Rapidly evolving neuropathies are often inflammatory, including acute inflammatory demyelinating polyneuropathy (AIDP) or Guillain-Barré syndrome (GBS); subacute evolution suggests an inflammatory, toxic, or nutritional cause; chronic neuropathies that are long-standing over years may be hereditary.
  6. Is there evidence for a hereditary neuropathy? Consider in pts with a slowly progressive distal weakness over many years with few sensory symptoms but significant sensory deficits on clinical examination. Most common is Charcot-Marie-Tooth disease (CMT; look for foot abnormalities such as high or flat arches and hammer toes as well as scoliosis).
  7. Does the pt have other medical conditions? Inquire about associated medical conditions (e.g., diabetes, systemic lupus erythematosus); preceding or concurrent infections (e.g., diarrheal illness preceding GBS); surgeries (e.g., gastric bypass and nutritional neuropathies); medications (toxic neuropathy); over-the-counter vitamin preparations (B6); alcohol, dietary habits; and use of dentures (because fixatives contain zinc that can lead to copper deficiency).

Based on the answers to these seven key questions, neuropathic disorders can be classified into several patterns based on the pattern of sensory, motor, and autonomic involvement (Table 196-1).

FIGURE 196-1
hmom20_ch196_f001.png

Approach to the evaluation of peripheral neuropathies. CIDP, chronic inflammatory demyelinating polyradiculoneuropathy; EDx, electrodiagnostic; GBS, Guillain-Barré syndrome; IVIg, intravenous immunoglobulin.

TABLE 196-1: Patterns of Neuropathic Disorders

Pattern 1: Symmetric proximal and distal weakness with sensory loss

 Consider: inflammatory demyelinating polyneuropathy (GBS and CIDP)

Pattern 2: Symmetric distal sensory loss with or without distal weakness

 Consider: cryptogenic or idiopathic sensory polyneuropathy (CSPN), diabetes mellitus and other metabolic disorders, drugs, toxins, familial (HSAN), CMT, amyloidosis, and others

Pattern 3: Asymmetric distal weakness with sensory loss

 With involvement of multiple nerves

   Consider: multifocal CIDP, vasculitis, cryoglobulinemia, amyloidosis, sarcoid, infectious (leprosy, Lyme, hepatitis B, C, or E, HIV, CMV), HNPP, tumor infiltration

 With involvement of single nerves/regions

   Consider: may be any of the above but also could be compressive mononeuropathy, plexopathy, or radiculopathy

Pattern 4: Asymmetric proximal and distal weakness with sensory loss

 Consider: polyradiculopathy or plexopathy due to diabetes mellitus, meningeal carcinomatosis or lymphomatosis, sarcoid, amyloid, hereditary plexopathy (HNPP, HNA), idiopathic

Pattern 5: Asymmetric distal weakness without sensory loss

 With upper motor neuron findings

   Consider: motor neuron disease

 Without upper motor neuron findings

   Consider: progressive muscular atrophy, juvenile monomelic amyotrophy (Hirayama’s disease), multifocal motor neuropathy, multifocal acquired motor axonopathy

Pattern 6: Symmetric sensory loss and distal areflexia with upper motor neuron findings

 Consider: Vitamin B12, vitamin E, and copper deficiency with combined system degeneration with peripheral neuropathy, chronic liver disease, hereditary leukodystrophies (e.g., adrenomyeloneuropathy) HSP-plus

Pattern 7: Symmetric weakness without sensory loss

 With proximal and distal weakness

   Consider: SMA

 With distal weakness

   Consider: hereditary motor neuropathy (“distal” SMA) or atypical CMT

Pattern 8: Focal midline proximal symmetric weakness

 Neck extensor weakness

   Consider: ALS

 Bulbar weakness

   Consider: ALS/PLS, isolated bulbar ALS (IBALS), Kennedy’s syndrome (X-linked, bulbospinal SMA), bulbar presentation GBS

 Diaphragm weakness (SOB)

   Consider: ALS

Pattern 9: Asymmetric proprioceptive sensory loss without weakness

 Consider causes of a sensory neuronopathy (ganglionopathy):

 Cancer (paraneoplastic)

 Sjögren’s syndrome

 Idiopathic sensory neuronopathy (possible GBS variant)

 Cisplatin and other chemotherapeutic agents

 Vitamin B6 toxicity

HIV-related sensory neuronopathy

Pattern 10: Autonomic symptoms and signs

 Consider neuropathies associated with prominent autonomic dysfunction:

 Hereditary sensory and autonomic neuropathy

 Amyloidosis (familial and acquired)

 Diabetes mellitus

 Idiopathic pandysautonomia (may be a variant of Guillain-Barré syndrome)

 Porphyria

HIV-related autonomic neuropathy

 Vincristine and other chemotherapeutic agents

Abbreviations: CIDP, chronic inflammatory demyelinating polyneuropathy; CMT, Charcot-Marie-Tooth disease; CMV, cytomegalovirus; GBS, Guillain-Barré syndrome; HIV, human immunodeficiency virus; HNA, hereditary neuralgic amyotrophy; HNPP, hereditary neuropathy with liability to pressure palsies; HSAN, hereditary sensory and autonomic neuropathy; HSP-plus, hereditary spastic paraplegia plus neuropathy; SMA, spinal muscular atrophy; SOB, shortness of breath.

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