Abducens nerve palsy refers to the syndrome of paralysis of the muscles innervated by the abducens nerve, caused by various etiologies that directly or indirectly affect or involve the nerve.
The abducens nerve nucleus is located in the deep part of the facial colliculus at the floor of the fourth ventricle at the level of the lower pons. It runs lateral to the internal carotid artery, exits the cavernous sinus, enters the orbit through the superior orbital fissure, passes through the common tendinous ring, and pierces the inner surface of the lateral rectus muscle to innervate it.
The etiology of abducens nerve palsy can be summarized into the following two categories:
I. Intracranial Diseases
For example, brain tumors, intracranial traumatic hematomas, and hypertensive encephalopathy (such as cerebral hemorrhage or massive cerebral infarction), as well as encephalitis or meningitis from various causes, can increase intracranial pressure. This often leads to abducens nerve palsy due to compression or stretching.
II. Extracranial Diseases
Conditions such as nasopharyngeal carcinoma, inflammation near the cavernous sinus and internal carotid artery, orbital inflammation, trauma, fractures, etc., can directly or indirectly affect and damage the abducens nerve, leading to the disease.
Key Diagnostic Criteria
Clinical abducens nerve palsy is the most common type of isolated cranial nerve palsy. The abducens nerve innervates the lateral rectus muscle. When the abducens nerve is paralyzed, the affected eye assumes an adducted position due to lateral rectus weakness. When fixation is attempted with the paralyzed eye, the healthy eye shows marked adduction (secondary deviation). Abducens nerve palsy results in diplopia. In mild cases, the head may turn toward the paralyzed side, or the head may tilt slightly forward. Bilateral abducens nerve palsy is relatively common, particularly in the context of elevated intracranial pressure.
Treatment
I. Acupoints and Needling Techniques
1. GB14 (Yangbai) (affected side): Located on the forehead, 1 cun directly above the midpoint of the eyebrow. Use a gauge-30, 1.5 cun filiform needle. Perform standard disinfection, then insert transversely toward the Yuyao point, advancing to the upper one-third of the upper eyelid. Needle sensation: distension and pain in the forehead and orbital region.
2. Transverse puncture from BL2 (Zanzhu) to TE23 (Sizhukong) (affected side): BL2 is located at the medial end of the eyebrow, in the supraorbital notch; TE23 is located in the depression at the lateral end of the eyebrow. Use a 30-gauge, 1.5 cun filiform needle. After routine local disinfection, pinch up the skin at BL2 and insert the needle down to the bone, then advance it subcutaneously (transverse puncture) to reach TE23. Needle sensation: distension and pain in the orbital region.
3. **Taiyang (EX-HN5)** (affected side): Located in the depression approximately 1 cun posterior to the midpoint between the lateral end of the eyebrow and the outer canthus. Use a 30-gauge filiform needle of 1.5 cun; after routine local disinfection, insert obliquely towards **GB8 (Shuaigu)** to a depth of about 1.2 cun. Sensation: local distension and mild pain.
4. **BL10 (Tianzhu)** on the affected side: Located 1.3 cun lateral to **GV15 (Yamen)**, in the depression on the lateral border of the trapezius muscle. Use a gauge 30, 2 cun filiform needle. After routine local disinfection, insert perpendicularly to a depth of approximately 1.5–1.8 cun. Needling sensation: local distension and pain.
## II. Methods
For unilateral conditions, select the affected side; for bilateral conditions, select both sides. The patient is seated. Insert the needles into the above-mentioned acupoints as per the method. Apply electrical stimulation for 40 minutes. When removing the needles, press the insertion sites with sterile cotton balls to prevent bleeding. Treatment is given once daily, with 7 sessions constituting one course. A rest of 3 days is taken before the next course.
Notes
For simple abducens nerve palsy caused by inflammatory involvement, the acupuncture methods described above yield excellent results. If the abducens nerve palsy is due to intracranial lesions, acupuncture treatment should be performed after the intracranial cause is resolved to achieve certain therapeutic effects. In cases of abducens nerve palsy resulting from compression or stretching of the nerve due to cerebral hemorrhage or cerebral thrombosis, the aforementioned method can be applied while concurrently treating the hemorrhage or thrombosis, supplemented by needling the visual area, to also achieve certain effects. During the treatment period, patients should be advised to wear tinted glasses to avoid excessive eye strain during vision, which may cause ocular discomfort and interfere with treatment.