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KembaraXtra -Medicine- Emergency and Acute Medicine – Peripheral Neuropathy
Peripheral neuropathy is a broad term describing disorders of peripheral nerves that may involve motor, sensory, or autonomic fibers. Patients commonly present with muscle weakness, atrophy, pain, numbness, or a combination of these symptoms. The condition may be acute or chronic, symmetric or asymmetric, and distal or proximal in distribution.
Etiology varies widely and depends on the clinical presentation. Causes include metabolic disorders, endocrine disease, nutritional deficiencies, toxins, medications, autoimmune conditions, infections, hereditary disorders, trauma, and neoplastic processes. Diabetes mellitus is the most common cause of symmetric peripheral neuropathy. Acute demyelinating processes such as Guillain–Barré syndrome must be considered in rapidly progressive cases.
Sensory nerve dysfunction presents with numbness, tingling, paresthesias, dysesthesias, or burning pain. Large-fiber neuropathy leads to decreased vibration and position sense, whereas small-fiber neuropathy affects pain and temperature sensation. Deep tendon reflexes are often reduced due to impairment of the sensory afferent limb. Symptoms typically follow a stocking-glove distribution in symmetric polyneuropathy.
Motor nerve involvement causes weakness, usually distal greater than proximal. Fasciculations may occur, and chronic disease can lead to muscle atrophy and diminished tone. Reflexes may be reduced or absent due to impaired motor efferent conduction.
Autonomic dysfunction may manifest as orthostatic hypotension, constipation, urinary retention, erectile dysfunction, or other signs of impaired autonomic regulation.
History should focus on duration of symptoms, pattern of involvement (symmetric versus asymmetric), distribution (distal versus proximal), and whether symptoms are sensory, motor, or mixed. Medication exposure, toxin exposure, systemic disease, recent infections, and family history should be reviewed.
Physical examination requires a thorough neurologic assessment, including strength testing, reflex evaluation, and detailed sensory examination. Sensory loss in a stocking-glove pattern supports a length-dependent polyneuropathy. Early absence of reflexes, particularly in an acute presentation, should raise concern for demyelinating neuropathy such as Guillain–Barré syndrome, which can progress to respiratory failure.
Essential evaluation depends on acuity and severity. In acute or rapidly progressive weakness, early neurology consultation is critical. Laboratory studies may include a basic metabolic panel, complete blood count, liver function tests, urinalysis, thyroid-stimulating hormone, and targeted testing such as HIV or vitamin B12 levels based on clinical suspicion. Electrocardiogram and imaging such as chest radiograph or head CT may be obtained when indicated by associated symptoms.
Electromyography and nerve conduction studies are typically arranged by neurology to characterize axonal versus demyelinating patterns. Lumbar puncture may be required when Guillain–Barré syndrome is suspected.
Differential diagnosis depends on distribution. Focal neuropathies are often due to entrapment syndromes such as carpal tunnel, ulnar tunnel, tarsal tunnel, or peroneal nerve compression. Multifocal neuropathy (mononeuropathy multiplex) may result from diabetes, vasculitis, connective tissue disease, sarcoidosis, leprosy, malignancy, or HIV infection. Symmetric polyneuropathy commonly results from diabetes, hypothyroidism, nutritional deficiency, alcohol use, medication toxicity, critical illness, electrolyte disturbances, toxins, or Guillain–Barré syndrome. Myelopathy may mimic peripheral neuropathy and should be suspected in patients with back pain, saddle anesthesia, or lower extremity weakness.
Initial management in the emergency setting focuses on airway protection in severe cases, especially when Guillain–Barré syndrome is suspected. Monitoring for respiratory compromise is essential. Offending toxins or medications should be discontinued, and underlying systemic conditions should be treated.
Pain control may include opioids when necessary. Neuropathic pain can be managed with agents such as gabapentin, titrated gradually to effect. Carbamazepine may be used for specific neuropathic syndromes such as trigeminal neuralgia. Intravenous immunoglobulin is indicated for Guillain–Barré syndrome.
Admission is required for patients with respiratory distress, acute gait disturbance, rapidly progressive weakness, or intractable pain. Stable patients without respiratory compromise or significant functional impairment may be discharged with appropriate outpatient follow-up.
Failure to recognize Guillain–Barré syndrome is a critical pitfall, as delayed diagnosis can lead to respiratory failure and significant morbidity. Early identification and appropriate monitoring are essential in patients with acute, progressive peripheral neuropathy.
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