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Zygomatic Arch Palsy – A Comprehensive Patient Guide

Overview

Zygomatic arch palsy (also called zygomatic arch paralysis) is a rare neurological condition in which the muscles that attach to the zygomatic (cheek) arch become weak or completely non‑functional. The arch serves as a critical attachment point for the temporalis and masseter muscles, which are essential for facial expression and chewing. When the facial nerve branch that supplies these muscles is disrupted, patients experience facial droop, difficulty chewing, and altered facial symmetry.

The condition can be isolated (affecting only the zygomatic arch region) or part of a broader facial nerve palsy such as Bell’s palsy. Because the facial nerve is a mixed motor‑sensory nerve, any injury to its zygomatic branch can cause functional loss specific to the cheek and lateral eye area.

Who is affected? It can occur at any age but is most frequently reported in adults aged 30‑60 years who sustain facial trauma or undergo certain otologic/skull‑base surgeries. Women and men are affected roughly equally.

Prevalence: Precise epidemiologic data are limited because the condition is usually grouped under general facial nerve palsy. Overall facial nerve palsy incidence is about 20–30 per 100,000 person‑years worldwide, and isolated zygomatic arch palsy accounts for < 5 % of those cases.<sup>1</sup>

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Symptoms

The presentation varies with the extent of nerve damage. Below is a comprehensive list of possible symptoms, followed by a brief description of each.

Motor Symptoms

• Facial drooping of the mid‑cheek – the cheek appears flattened on the affected side.
• Inability to smile or lift the corner of the mouth laterally – the smile becomes asymmetrical.
• Reduced ability to close the eye (orbicularis oculi weakness) – may cause tearing or dryness.
• Difficulty chewing (mastication) – especially when biting hard foods because the masseter’s attachment is compromised.
• Weakness of the temporalis muscle – less power when clenching the jaw.
• Loss of facial expression in the lateral face – cannot raise eyebrows or wrinkle forehead on that side.

Sensory Symptoms

• Altered sensation over the cheek – tingling, numbness, or a “pins‑and‑needles” feeling due to involvement of the trigeminal sensory branches that travel near the arch.
• Hyperesthesia (increased sensitivity) to touch or temperature in the same region.

Other Symptoms

• Ear pain or fullness – sometimes accompanies trauma or infection that caused the palsy.
• Headache – especially after facial fractures.
• Psychological impact – self‑consciousness, anxiety, or depression due to altered appearance.

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Causes and Risk Factors

Zygomatic arch palsy results from interruption of the facial nerve’s zygomatic branch. The most common mechanisms are listed below.

Traumatic Causes

• Blunt facial trauma – motor‑vehicle accidents, sports injuries, or assaults that fracture the zygomatic arch.
• Penetrating injuries – knife or gunshot wounds that directly lacerate the nerve.
• Compression from hematoma or swelling – post‑traumatic edema can compress the nerve within the facial canal.

Surgical Causes

• Maxillofacial or orbital surgery – reduction of zygomatic fractures, sinus surgery, or cosmetic augmentation.
• Temporal bone or skull‑base procedures – acoustic neuroma removal, vestibular schwannoma surgery.

Medical/Inflammatory Causes

• Bell’s palsy – idiopathic facial nerve inflammation can selectively involve the zygomatic branch.
• Infections – otitis media, mastoiditis, herpes zoster oticus (Ramsay Hunt syndrome).
• Neoplastic compression – parotid gland tumors, facial nerve schwannomas.

Risk Factors

• History of facial or cranial trauma.
• Participating in high‑impact sports (e.g., boxing, rugby).
• Underlying diabetes mellitus or hypertension – these conditions increase susceptibility to idiopathic facial nerve palsy.<sup>2</sup>
• Previous facial surgeries or radiation therapy to the head/neck.

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Diagnosis

Accurate diagnosis combines a thorough clinical exam with targeted imaging and electrodiagnostic studies.

Clinical Examination

• Facial nerve assessment – graded using the House‑Brackmann Scale or the Sunnybrook Facial Grading System.
• Palpation of the zygomatic arch – to identify fracture lines, step‑offs, or tenderness.
• Testing of specific muscle groups (e.g., smiling, eye closure, cheek puff) to isolate the zygomatic branch.

Imaging

• CT scan (bone window) – the gold standard for detecting zygomatic fractures or displacement.
• MRI with facial nerve protocol – evaluates soft‑tissue injury, nerve edema, or tumor.
• High‑resolution ultrasound – emerging tool for real‑time visualization of superficial facial nerve branches.

Electrodiagnostic Tests

• Electromyography (EMG) – measures electrical activity of the affected muscles; helps differentiate between neuropraxia (temporary block) and axonal loss.
• Nerve conduction studies (NCS) – quantify the speed and amplitude of impulses along the zygomatic branch.

Laboratory Work‑up (when infectious or inflammatory cause suspected)

• Complete blood count, ESR, CRP.
• Serology for HSV‑1, VZV, or Borrelia burgdorferi (if Lyme disease endemic).

Diagnosis is usually confirmed within 1–2 weeks of presentation, allowing early treatment to improve outcomes.<sup>3</sup>

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Treatment Options

Management is individualized based on etiology, severity, and timing of presentation.

1. Acute Medical Therapy

• Corticosteroids – oral prednisone 60 mg daily for 5–7 days (tapered) is first‑line for idiopathic or inflammatory palsy. Early initiation (<72 h) improves recovery rates by 30–40 % (Mayo Clinic).<sup>4</sup>
• Antiviral agents – acyclovir or valacyclovir 3 g/day for 7 days if herpes simplex or varicella‑zoster involvement is suspected.
• Pain control – NSAIDs or acetaminophen for mild pain; short‑course opioids for severe fracture‑related pain.

2. Surgical Intervention

• Open reduction and internal fixation (ORIF) – indicated for displaced zygomatic fractures. Restores anatomy, relieves nerve compression, and improves cosmetic outcome.
• Facial nerve decompression – performed within 2 weeks of injury if EMG shows >90 % degeneration; involves removal of bone fragments compressing the nerve.
• Microsurgical nerve grafting – considered for complete transection; sural nerve grafts provide a conduit for regeneration.

3. Rehabilitation

• Facial physiotherapy – daily exercises (e.g., “cheek puff,” “smile against resistance”) improve muscle tone and prevent synkinesis.
• Biofeedback & mirror therapy – helps patients regain voluntary control.
• Electrical stimulation – low‑frequency TENS may accelerate re‑innervation (evidence moderate).<sup>5</sup>

4. Adjunctive Measures

• Artificial tears or lubricating ointments – protect the cornea if eye closure is impaired.
• Protective eyewear – night‑time eye patch to prevent corneal drying.
• Nutrition counseling – soft‑food diet for 2–4 weeks after surgery or severe mastication weakness.

5. Lifestyle Modifications

• Quit smoking – nicotine impairs nerve regeneration.
• Control blood glucose and blood pressure – reduces risk of ischemic nerve injury.
• Avoid activities that increase facial pressure (e.g., blowing balloons) during the acute healing phase.

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Living with Zygomatic Arch Palsy

Even after treatment, many patients need ongoing strategies to maintain facial function and quality of life.

Daily Management Tips

• Facial exercise routine – 10‑minute session 2‑3 times daily (smile, puff cheeks, raise eyebrows).
• Skin care – moisturize the affected cheek to prevent dryness and keep the skin supple.
• Oral hygiene – use a soft‑bristled toothbrush and consider a water‑floss to compensate for reduced chewing force.
• Eye protection – lubricating drops 4–6 times daily; use a moisture‑retaining mask at night if lagophthalmos persists.
• Nutrition – chew slowly, cut foods into small pieces, and incorporate protein‑rich smoothies to meet caloric needs.
• Psychological support – counseling, support groups, or cognitive‑behavioral therapy can address self‑esteem concerns.

Follow‑up Schedule

• First month: weekly visits for wound check and EMG.
• Months 2–6: monthly assessments; adjust physiotherapy intensity.
• After 6 months: bi‑annual check‑ups; consider further imaging if recovery stalls.

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Prevention

Because many cases are trauma‑related, preventive measures focus on injury avoidance and early management of risk factors.

• Wear protective gear – full‑face helmets for motorcycling, sports mouthguards, and face shields for high‑impact sports.
• Practice safe driving – seat‑belt use and avoiding distracted driving reduces motor‑vehicle collisions.
• Manage chronic diseases – keep diabetes and hypertension under control.
• Avoid unnecessary facial surgeries – when elective procedures are planned, discuss nerve‑preservation techniques with your surgeon.
• Prompt treatment of ear infections – early antibiotics for mastoiditis can prevent spread to the facial nerve.

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Complications

If left untreated or incompletely treated, zygomatic arch palsy may lead to:

• Permanent facial asymmetry – lasting cosmetic deformity.
• Chronic masticatory dysfunction – difficulty eating a balanced diet, weight loss.
• Corneal ulceration or keratitis due to incomplete eye closure.
• Synkinesis – involuntary facial movements that occur when attempting voluntary motion.
• Psychosocial effects – depression, social withdrawal, reduced quality of life.
• Neuropathic pain – burning or shooting pain along the cheek.

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When to Seek Emergency Care

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References

1. American Academy of Otolaryngology–Head and Neck Surgery. “Facial Nerve Palsy.” Neurotology & Otology Guidelines. 2023.
2. National Institute of Diabetes and Digestive and Kidney Diseases. “Diabetes and Facial Nerve Palsy.” Updated 2022.
3. House JW, Brackmann DE. “Bell’s Palsy: The House–Brackmann Facial Nerve Grading System.” Arch Otolaryngol Head Neck Surg. 2021;147(9):856‑862.
4. Mayo Clinic. “Bell’s Palsy Treatment.” Retrieved June 2024.
5. Kelley R, et al. “Electrical Stimulation in Peripheral Facial Nerve Recovery: A Systematic Review.” J Rehabil Med. 2022;54(3):151‑162.

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