Polyneuritis: Causes, Bilateral Symptoms, and Acupuncture Treatment

Polyneuritis is a group of extensive peripheral nerve diseases with a relatively complex etiology, primarily characterized by the simultaneous involvement of the distal parts of both limbs. It is also known as a peripheral neuropathy.

Neuritis or peripheral neuritis.

The causes are numerous; the common ones include:

1. Poisoning: Such as heavy metal poisoning from arsenic, lead, mercury, bismuth, antimony, copper, phosphorus, thallium, etc., or chemical substances commonly used in industry, agriculture, and medicine, including acrylamide, aniline, carbon monoxide, carbon dioxide, carbon tetrachloride, nitrofuran drugs, isoniazid, vincristine, sulfonamides, chlorobutanol, tetrachloroethane, chloroquine, emetine, streptomycin, phenytoin sodium, dinitrobenzene, etc.

2. Nutritional and metabolic disorders: such as vitamin B complex (including niacin) deficiency, chronic alcoholism, diabetes mellitus, porphyria, pregnancy, chronic gastrointestinal diseases, and post-surgical conditions.

3. Infection: This may include direct neural infection (e.g., leprosy, leptospirosis, infectious mononucleosis, brucellosis, etc.) or conditions occurring secondary to acute or chronic infectious diseases (e.g., dysentery, influenza, typhoid fever, malaria, measles, meningitis, herpes zoster, etc.). Certain bacterial endotoxins may also invade the peripheral nerves, as seen in diphtheria and tetanus. Other causes may include post-infectious or allergic reactions (e.g., Guillain-Barré syndrome, serum or post-vaccination polyneuritis), connective tissue diseases, and genetic factors. In a considerable number of patients, the etiology remains unknown.

The pathological changes of polyneuritis caused by different etiologies lack specific features, primarily manifesting as non‑inflammatory degeneration, including segmental demyelination and axonal degeneration. In the early stage, myelin edema and disintegration occur, followed by axonal destruction.

Key Diagnostic Points

Polyneuritis caused by any clinical etiology shares similar major symptoms. Most pathogenic factors simultaneously affect motor and sensory fibers, manifesting as sensory-motor neuropathy—a symmetrical dysfunction of sensory, motor, and autonomic nerves predominantly in the distal extremities, often more severe in the lower limbs. Some etiologies may selectively affect motor or sensory fibers, resulting in predominantly motor or sensory symptoms. In the early stage of sensory disturbance, irritative symptoms are prominent, often including burning sensation, pain, paresthesia, or hyperesthesia. Subsequently, hypoesthesia for pain, temperature, touch, tuning fork vibration sense, and joint position sense appears, presenting a glove-and-stocking distribution. Motor disturbances manifest as muscle weakness, paralysis of varying degrees, and hypotonia (decreased muscle tone).

Below, muscle atrophy, diminished or absent tendon reflexes. Autonomic nervous dysfunction manifests as thinning or softening of the skin on the hands and feet, or hyperkeratosis, hyperhidrosis, flushing or cyanosis, decreased temperature, etc. The severity of the condition varies; mild cases may only have acral pain and numbness without sensory loss or motor impairment. The course is mostly acute or subacute, recurrent.

For some patients with this condition, diagnosis may require auxiliary examinations such as electromyography (EMG), nerve conduction velocity (NCV), nerve biopsy, and blood and urine tests.

【Treatment】

1. Acupuncture Points and Needling Techniques

1. **TE5 (Waiguan)** (bilateral): Located on the dorsal aspect of the forearm, on the line connecting **Yangchi (TE4)** and the tip of the elbow, 2 *cun* proximal to the dorsal wrist crease (at Yangchi), between the ulna and radius. Use a 30-gauge, 2-cun filiform needle. Perform routine local disinfection. Puncture perpendicularly toward **PC6 (Neiguan)** to a depth of approximately 1.6 *cun*. Needling sensation: local distension and pain, or radiation toward the elbow.

2. **Baxie (EX-UE9)** (bilateral): Located on the dorsum of the hand, with the hand slightly clenched, between the 1st to 5th fingers, at the junction of the red and white flesh just behind the web margins. There are 8 points in total (left and right sides). A 30-gauge, 1.5-cun filiform needle is used. After routine local disinfection, each needle is inserted obliquely upward along the intermetacarpal space for about 1.2 cun. Needling sensation: local distention and pain.

3. SP6 (Sanyinjiao) (bilateral): Located 3 cun directly above the medial malleolus, on the posterior border of the medial aspect of the tibia. Using a 30-gauge, 2-cun filiform needle, after routine local disinfection, insert perpendicularly toward GB39 (Xuanzhong) to a depth of approximately 1.8 cun. Needle sensation: local distension and pain.

**4. Bafeng Points (EX-LE10) (Bilateral):** Located on the dorsum of the foot, between the 1st to 5th toes, at the junction of the red and white skin proximal to the interdigital web margins, with 8 points on both sides. Using a gauge 30 filiform needle of 1.5 cun, after routine local disinfection, insert obliquely upward into each point to a depth of approximately 1.2 cun. **Needling sensation:** Local distension and pain.

II. Methods

The patient is seated. Insert the needles into the selected acupoints according to the standard method. Retain the needles for 40 minutes, with one intermediate needle-twisting (stimulation). Treatment is administered once daily, and 10 sessions constitute one course. After completing the course, rest for 5 days before resuming needling.

【Commentary】

Polyneuritis generally has a favorable prognosis. Acupuncture treatment, typically performed when the condition is stable (without fever), can yield satisfactory results. Acupuncture is applied to treat this condition.

Clinical Manifestations of Polyneuritis

Polyneuritis, also referred to as peripheral neuritis, is characterized by a diffuse, symmetric involvement of the peripheral nerves. The hallmark of this condition is the presentation of polyneuritis symptoms bilateral distal limbs, which typically manifests as a progressive, symmetrical impairment of motor and sensory functions in the feet and hands. Patients frequently report paresthesias, such as numbness, tingling, or burning sensations, beginning in the toes and fingers and gradually ascending. Motor deficits include muscle weakness, atrophy, and diminished deep tendon reflexes, often leading to a “waddling” gait or foot drop. The distal-to-proximal gradient underscores the length-dependent nature of axonal degeneration, which is a common pathological feature in many forms of polyneuritis. This pattern of bilateral limb involvement is critical for clinical diagnosis, as it helps differentiate polyneuritis from mononeuritis or focal neuropathies. The severity and progression depend on the underlying etiology, but early recognition of these symmetric distal symptoms is essential for prompt intervention to prevent irreversible nerve damage.

Etiological Pathways: The Role of Heavy Metals

The causes of polyneuritis are diverse, yet one prominent and preventable category is toxic neuropathy induced by environmental and occupational exposures. Among these, multiple neuritis causes heavy metal poisoning stands as a well-documented etiological mechanism. Heavy metals such as arsenic, lead, mercury, and thallium exert neurotoxic effects through various pathways, including inhibition of key enzymes, oxidative stress, and disruption of axonal transport. Arsenic, in particular, is a potent neurotoxin that can produce a severe, symmetrical sensorimotor polyneuropathy, often accompanied by systemic signs like skin changes and gastrointestinal distress. Chronic exposure to lead may cause a predominantly motor neuropathy, while mercury and thallium affect both sensory and autonomic fibers. The diagnosis of heavy metal–induced polyneuritis relies on a thorough occupational and environmental history, along with confirmatory laboratory testing, such as measuring metal concentrations in blood, urine, or hair. Recognizing these causative agents is imperative, as removal of the source is the cornerstone of management and can halt disease progression.

Management Strategies: Focus on Arsenic Intoxication

Treatment of polyneuritis must address both the underlying cause and symptomatic supportive care. In cases of toxic neuropathy, the primary intervention is cessation of exposure and, when feasible, enhancement of toxin elimination. For instance, arsenic poisoning polyneuritis treatment involves the immediate removal of the individual from the contaminated environment and the administration of chelating agents such as dimercaprol (British anti-Lewisite) or 2,3-dimercaptosuccinic acid (DMSA). These agents bind inorganic arsenic, increasing its urinary excretion and reducing tissue burden. However, chelation is most effective when initiated early, before irreversible nerve damage occurs. Adjunctive therapies include physical and occupational rehabilitation to maintain muscle strength and functional independence, as well as pain management with agents like gabapentin or tricyclic antidepressants for neuropathic pain. Nutritional support, particularly with B vitamins, may aid nerve regeneration. While recovery from arsenic-induced polyneuritis can be slow and incomplete, timely and comprehensive management optimizes neurological outcomes. Ongoing monitoring for residual deficits is essential, emphasizing the importance of preventive measures in at-risk populations.