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Reduction Malarplasty: Complications and Management


Surgical procedures involving the craniofacial region, such as reduction malarplasty with L-shaped osteotomy and sagittal split ramus osteotomy (SSRO) of the mandible, are integral for correcting facial deformities and improving aesthetic outcomes. However, despite meticulous planning and precise execution, these complex surgeries carry inherent risks, including injury to critical anatomical structures.


In this blog, we delve into two significant complications associated with these procedures: injury to the deep facial vein during L-shaped osteotomy and facial nerve palsy following SSRO of the mandible. Understanding the mechanisms, clinical implications, and preventive strategies for these complications is essential for optimizing patient safety and surgical outcomes in craniofacial surgery.


I. Injury to the Deep Facial Vein during L-shaped Osteotomy



The L-shaped osteotomy technique involves the creation of strategic bone cuts in the zygomatic bone to allow for its repositioning and reduction. These bone cuts are typically made using surgical instruments such as osteotomes or saws, guided by preoperative planning and anatomical landmarks.

The deep facial vein courses within close proximity to the zygomatic bone, specifically in the vicinity of the zygomatico-orbital and zygomatico-maxillary regions. Injury to the deep facial vein can occur due to direct trauma from surgical instruments, excessive manipulation of tissues, or unintentional bone fractures extending into vascular channels. Once the vein is injured, it can lead to significant bleeding, potentially compromising patient safety.


Contributing Factors


  1. Anatomical Variability: The precise course and location of the deep facial vein may exhibit variability among individuals. While general anatomical principles can guide surgical planning, variations in vascular anatomy may predispose certain patients to increased risk of inadvertent vessel injury.

  2. Surgical Access and Visualization: Achieving adequate exposure and visualization of the surgical field is essential during L-shaped osteotomy. However, manipulation of soft tissues and retraction of surrounding structures to optimize access can inadvertently increase the risk of trauma to nearby vascular structures, including the deep facial vein.

  3. Instrumentation and Technique: The use of surgical instruments for bone cutting and manipulation introduces mechanical forces that can propagate beyond the intended osteotomy site. Improper instrument positioning or excessive force application may result in unintended extension of bone cuts into vascular territories, leading to vascular injury.

  4. Bone-Blood Vessel Relationships: The zygomatic bone is intimately associated with adjacent vascular structures through osseous and soft tissue connections. As such, alterations in the position or integrity of the zygomatic bone during osteotomy may disrupt the anatomical relationships with neighboring blood vessels, predisposing them to injury.


Clinical Presentation


Injury to the deep facial vein during L-shaped osteotomy can manifest with various clinical presentations depending on the extent and severity of the vascular trauma. Common clinical features may include:

  1. Significant Bleeding: Intraoperative or postoperative hemorrhage is a hallmark sign of deep facial vein injury. Profuse bleeding may occur at the surgical site, leading to hematoma formation and potential compromise of surgical field visibility.

  2. Hematoma Formation: Accumulation of blood within the surgical site or adjacent soft tissues can result in palpable swelling and ecchymosis (bruising) in the periorbital and zygomatic regions.

  3. Hemodynamic Instability: Severe bleeding from the deep facial vein can precipitate hemodynamic instability, characterized by hypotension, tachycardia, and signs of shock.

  4. Pain and Discomfort: Patients may experience localized pain, tenderness, or discomfort in the zygomatic region secondary to hematoma formation and tissue distension.

  5. Ecchymosis and Edema: The presence of ecchymosis (bruising) and edema in the periorbital and zygomatic regions is indicative of vascular trauma and extravasation of blood into surrounding tissues.


Injury Management


  1. Immediate Hemostasis: Prompt identification and control of bleeding are paramount to prevent further blood loss and maintain hemodynamic stability. Direct pressure, topical hemostatic agents, and meticulous surgical hemostasis techniques may be employed to achieve hemostasis.

  2. Surgical Exploration: In cases of significant bleeding or suspected vascular injury, surgical exploration of the affected area may be necessary to identify and address the source of hemorrhage. Careful dissection and visualization of vascular structures facilitate direct repair or ligation of injured vessels.

  3. Hemodynamic Support: Patients experiencing hemodynamic instability due to blood loss require vigilant monitoring and supportive measures. Intravenous fluid resuscitation, blood transfusion, and vasopressor therapy may be indicated to maintain perfusion and restore hemodynamic stability.

  4. Postoperative Monitoring: Following surgical intervention, close monitoring of the patient's clinical status, vital signs, and hematologic parameters is essential to detect and manage postoperative complications, such as hematoma expansion or rebleeding.

  5. Preventive Strategies: Implementation of preventive measures, including meticulous surgical technique, careful preoperative planning, and intraoperative monitoring of vascular structures, can help minimize the risk of deep facial vein injury during L-shaped osteotomy.


II. Facial Nerve Palsy Following Sagittal Split Ramus Osteotomy (SSRO) of the Mandible



SSRO is a common surgical procedure employed to correct mandibular deficiencies, such as mandibular prognathism or retrognathism. This technique involves making precise bone cuts along the mandibular ramus, allowing for repositioning of the lower jaw to achieve proper alignment and facial harmony.

The facial nerve, also known as the seventh cranial nerve, is a crucial neural structure responsible for motor innervation of the muscles of facial expression. It courses through the temporal bone, traversing intricate bony canals and branching into multiple branches, including the temporal, zygomatic, buccal, marginal mandibular, and cervical branches.


During SSRO, the surgical approach and bone cuts are carefully planned to avoid injury to the facial nerve and its branches. However, due to the proximity of the facial nerve to the mandibular ramus and the complex nature of the surgical procedure, there exists a risk of inadvertent nerve trauma.


Mechanism of Facial Nerve Palsy:


  1. Direct Trauma: Intraoperative manipulation of the mandibular ramus and adjacent tissues can inadvertently lead to direct mechanical trauma to the facial nerve or its branches. This may occur during bone cutting, retraction of soft tissues, or placement of fixation screws or plates.

  2. Compression or Stretch Injury: Tension or compression exerted on the facial nerve during surgical manipulation or repositioning of the mandibular segments can result in nerve compression or stretch injury. This can disrupt the neural integrity and impair nerve conduction, leading to facial nerve dysfunction.

  3. Ischemic Injury: Surgical manipulation and repositioning of the mandibular segments may compromise vascular supply to the facial nerve, leading to ischemic injury. Diminished blood flow to the nerve can impair oxygen and nutrient delivery, predisposing it to neural ischemia and subsequent dysfunction.

  4. Inflammatory Response: Surgical trauma and tissue manipulation can elicit an inflammatory response, characterized by local edema and tissue swelling. Inflammation in the vicinity of the facial nerve can impede neural conduction and exacerbate nerve dysfunction.

Clinical Presentation:


  1. Asymmetrical Facial Expression: Facial nerve palsy typically results in asymmetry of facial expression, with noticeable drooping or weakness of the affected side of the face. This asymmetry may be most apparent during voluntary movements such as smiling, grimacing, or raising the eyebrows.

  2. Loss of Forehead Wrinkles: Inability to raise the eyebrow or furrow the forehead on the affected side due to paralysis of the frontalis muscle results in loss of forehead wrinkles (frontal creases) on that side.

  3. Incomplete Eye Closure (Lagophthalmos): Dysfunction of the orbicularis oculi muscle, responsible for eyelid closure, can lead to incomplete or insufficient closure of the eyelid on the affected side. This may result in exposure of the cornea and predispose to ocular surface irritation or dryness.

  4. Drooping of the Corner of the Mouth (Mouth Deviation): Paralysis of the muscles controlling the lower face, such as the orbicularis oris and depressor anguli oris, can cause downward deviation or drooping of the corner of the mouth on the affected side during smiling or at rest.

  5. Altered Nasolabial Fold: Loss of muscle tone and function in the affected cheek can lead to flattening or disappearance of the nasolabial fold, the crease running from the side of the nose to the corner of the mouth, on the affected side.

  6. Speech and Swallowing Difficulty: Facial nerve palsy may impact speech articulation and swallowing function due to impaired control of the muscles involved in these processes, such as the buccinator muscle and muscles of the soft palate.

  7. Hyperacusis: Some patients may experience heightened sensitivity to sound (hyperacusis) on the affected side due to dysfunction of the stapedius muscle, which normally dampens excessive sound transmission through the middle ear.


Injury Management


  1. Early Assessment and Diagnosis: Immediate evaluation of the patient's facial nerve function is essential upon recognition of facial nerve palsy following SSRO. Clinical examination should include assessment of facial symmetry, voluntary facial movements, eye closure, forehead wrinkles, nasolabial fold, and muscle tone. Additional diagnostic modalities such as electromyography (EMG), nerve conduction studies, and imaging studies (e.g., magnetic resonance imaging [MRI]) may be utilized to assess nerve integrity and identify the site and extent of nerve injury.

  2. Multidisciplinary Approach: Management of facial nerve palsy following SSRO requires a multidisciplinary team approach involving oral and maxillofacial surgeons, neurologists, otolaryngologists, ophthalmologists, and physical therapists. Collaboration among team members facilitates comprehensive evaluation, treatment planning, and rehabilitation to optimize patient outcomes.

  3. Conservative Management: In cases of transient or incomplete facial nerve palsy, conservative management strategies may be employed. Eye care measures such as lubricating eye drops, ointments, or moisture chamber goggles are utilized to prevent corneal exposure and protect ocular integrity in patients with incomplete eyelid closure (lagophthalmos). Facial muscle exercises, massage, and electrical stimulation techniques may be initiated to promote neuromuscular re-education, maintain muscle tone, and prevent disuse atrophy.

  4. Botulinum Toxin Injection: Botulinum toxin (Botox) injection into the unaffected facial muscles may be considered to achieve temporary paralysis and symmetry by reducing hyperkinetic movements on the unaffected side. Targeted injection of Botox can help balance facial symmetry and improve aesthetic outcomes while awaiting nerve recovery.

  5. Surgical Intervention: Surgical exploration and decompression of the facial nerve may be warranted in cases of severe or persistent facial nerve palsy with evidence of nerve compression or entrapment. Revision surgery to release adhesions, remove compressive scar tissue, or reposition bony fragments causing nerve impingement may be performed to alleviate pressure on the facial nerve and facilitate neural regeneration.

  6. Rehabilitation and Physical Therapy: Early initiation of physical therapy and rehabilitation programs focusing on facial muscle strengthening, range of motion exercises, and proprioceptive training is essential to promote functional recovery and mitigate long-term sequelae. Patients should be instructed on home exercise regimens and encouraged to actively participate in facial exercises to optimize facial muscle function and prevent contractures.

  7. Long-term Monitoring and Follow-up: Long-term monitoring of facial nerve function and regular follow-up visits are necessary to assess progress, monitor complications, and adjust treatment strategies as needed. Serial clinical evaluations, electromyographic studies, and patient-reported outcomes should be utilized to track recovery and guide ongoing management decisions.

III. Past Research


Facial Nerve Palsy After Sagittal Split Ramus Osteotomy of the Mandible: Mechanism and Outcomes (2010)


This study examines the occurrence, causes, management, and outcomes of facial nerve palsy following sagittal split ramus osteotomy (SSRO) of the mandible. The research, conducted at the Craniofacial Center, Chang Gung Memorial Hospital, Taiwan, between 1981 and 2008, involved 3,105 patients who underwent SSRO. Among them, 6 patients (0.1%) experienced postoperative facial nerve palsy, with one case diagnosed as Bell’s palsy.


Facial Nerve Palsy After Sagittal Split Ramus Osteotomy of the Mandible: Mechanism and Outcomes (2010)

The study underscores that most facial nerve palsies after SSRO are likely due to neurapraxia or axonotmesis, potentially from nerve compression or traction during surgery. Remarkably, all patients in the study recovered without surgical intervention, receiving instead physical therapy and medication. The majority achieved complete recovery within six months, except for one patient who had incomplete frontal branch recovery.


Moreover, the research highlights the importance of early assessment and conservative management, emphasizing the need for expectant observation and avoiding surgical exploration unless direct transection of the facial nerve is suspected. It also discusses possible causative mechanisms, such as unprotected osteotome use, fractures, and postoperative complications contributing to facial nerve injury. In conclusion, the study suggests that facial nerve palsy following SSRO is rare but usually resolves spontaneously with conservative treatment. It emphasizes the significance of understanding the nature of nerve injury, implementing appropriate management strategies, and minimizing risks during surgical procedures.


In conclusion, while surgical procedures targeting the craniofacial region like reduction malarplasty with L-shaped osteotomy and sagittal split ramus osteotomy (SSRO) of the mandible are essential for correcting facial deformities and enhancing aesthetic outcomes, they are not without risks. This blog has extensively explored two significant complications associated with these surgeries: deep facial vein injury during L-shaped osteotomy and facial nerve palsy following SSRO. Understanding the mechanisms, clinical presentations, and management strategies for these complications is paramount for ensuring patient safety and optimizing surgical outcomes in craniofacial surgery. Moreover, past research, such as the study on facial nerve palsy after SSRO, underscores the importance of early assessment, conservative management, and multidisciplinary collaboration in addressing these complications effectively. By implementing preventive measures, employing meticulous surgical techniques, and prioritizing patient-centered care, surgeons can minimize risks and enhance the overall success of craniofacial surgical procedures.


Reference:

Avoiding Facial Nerve Injury in Oral and Maxillofacial Surgery (2021)

Facial Nerve Palsy After Sagittal Split Ramus Osteotomy of the Mandible: Mechanism and Outcomes (2010)


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