Surgical Considerations for the Submandibular and Parotid Glands

When performing surgery on the submandibular and parotid glands, it is crucial to be aware of the anatomical structures and nerves at risk to minimize complications. Below is an overview of the key nerves and anatomical landmarks relevant to these surgical procedures.

Major Nerves at Risk During Submandibular Gland Surgery

1. Hypoglossal Nerve (CN XII):

   • This nerve is responsible for motor innervation to the muscles of the tongue. It lies deep to the submandibular gland and is at risk during surgical manipulation in this area.

2. Marginal Mandibular Nerve:

   • A branch of the facial nerve (CN VII), the marginal mandibular nerve innervates the muscles of the lower lip and chin. It runs just deep to the superficial layer of the deep cervical fascia, below the platysma muscle, making it vulnerable during submandibular gland surgery.

3. Lingual Nerve:

   • The lingual nerve provides sensory innervation to the anterior two-thirds of the tongue and carries parasympathetic fibers to the submandibular gland via the submandibular ganglion. It is located in close proximity to the submandibular gland and is at risk during dissection.

Anatomical Considerations for Parotid Gland Surgery

• Parotid Fascia:

  • The parotid gland is encased in a capsule of parotid fascia, which provides a protective layer during surgical procedures.

• Facial Nerve (CN VII):

  • The facial nerve is a critical structure to identify during parotid gland surgery to prevent injury. Key landmarks for locating the facial nerve include:
    • Tympanomastoid Suture Line: This is a reliable landmark for identifying the main trunk of the facial nerve, which lies just deep and medial to this suture.
    • Tragal Pointer: The nerve is located about 1 cm deep and inferior to the tragal pointer, although this landmark is less reliable.
    • Posterior Belly of the Digastric Muscle: This muscle provides a reference for the approximate depth of the facial nerve.
    • Peripheral Buccal Branches: While following these branches can help identify the nerve, this should not be the standard approach due to the risk of injury.

Submandibular Gland Anatomy

• Location:

  • The submandibular gland is situated in the submandibular triangle of the neck, which is bordered by the mandible and the digastric muscles.

• Mylohyoid Muscle:

  • The gland wraps around the mylohyoid muscle, which is typically retracted anteriorly during surgery to provide better exposure of the gland.

• CN XII:

  • The hypoglossal nerve lies deep to the submandibular gland, making it important to identify and protect during surgical procedures.

Le Fort I Fracture

• A horizontal fracture that separates the maxilla from the nasal and zygomatic bones. It is also known as a "floating maxilla."

Signs and Symptoms:

1. Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
2. Disturbed Occlusion: Malocclusion due to displacement of the maxilla.
3. Mobility of the Maxilla: The maxilla may move independently of the rest of the facial skeleton.
4. Nasal Bleeding: Possible epistaxis due to injury to the nasal mucosa.
5. CSF Rhinorrhea: If there is a breach in the dura mater, cerebrospinal fluid may leak from the nose.

Le Fort II Fracture

• A pyramidal fracture that involves the maxilla, nasal bones, and the zygomatic bones. It is characterized by a fracture line that extends from the nasal bridge to the maxilla and zygomatic arch.

Signs and Symptoms:

1. Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
2. Diplopia: Double vision due to involvement of the orbital floor and potential muscle entrapment.
3. Enophthalmos: Posterior displacement of the eyeball within the orbit.
4. Restriction of Globe Movements: Limited eye movement due to muscle entrapment.
5. Disturbed Occlusion: Malocclusion due to displacement of the maxilla.
6. Nasal Bleeding: Possible epistaxis.
7. CSF Rhinorrhea: If the dura is torn, cerebrospinal fluid may leak from the nose.

Le Fort III Fracture

• A craniofacial disjunction fracture that involves the maxilla, zygomatic bones, and the orbits. It is characterized by a fracture line that separates the entire midface from the skull base.

Signs and Symptoms:

1. Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
2. Orbital Dystopia: Abnormal positioning of the orbits, often with an antimongoloid slant.
3. Diplopia: Double vision due to muscle entrapment or damage.
4. Enophthalmos: Posterior displacement of the eyeball.
5. Restriction of Globe Movements: Limited eye movement due to muscle entrapment.
6. Disturbed Occlusion: Significant malocclusion due to extensive displacement of facial structures.
7. CSF Rhinorrhea: If there is a breach in the dura mater, cerebrospinal fluid may leak from the nose or ears (CSF otorrhea).
8. Bleeding Over Mastoid Process (Battle’s Sign): Bruising behind the ear may indicate a skull base fracture.

Management of Skin Loss in the Face

Skin loss in the face can be a challenging condition to manage, particularly when it involves critical areas such as the lips and eyelids. The initial assessment of skin loss may be misleading, as retraction of skin due to underlying muscle tension can create the appearance of tissue loss. However, when significant skin loss is present, it is essential to address the issue promptly and effectively to prevent complications and promote optimal healing.

Principles of Management

1. Assessment Under Anesthesia: A thorough examination under anesthesia is necessary to accurately assess the extent of skin loss and plan the most suitable repair strategy.

2. No Healing by Granulation: Unlike other areas of the body, wounds on the face should not be allowed to heal by granulation. This approach can lead to unacceptable scarring, contracture, and functional impairment.

3. Repair Options: The following options are available for repairing skin loss in the face:

   • Skin Grafting: This involves transferring a piece of skin from a donor site to the affected area. Skin grafting can be used for small to moderate-sized defects.
   • Local Flaps: Local flaps involve transferring tissue from an adjacent area to the defect site. This approach is useful for larger defects and can provide better color and texture match.
   • Apposition of Skin to Mucosa: In some cases, it may be possible to appose skin to mucosa, particularly in areas where the skin and mucosa are closely approximated.

Types of skin grafts:

Split-thickness skin graft (STSG):The most common type, where only the epidermis and a thin layer of dermis are harvested.

Full-thickness skin graft (FTSG):Includes the entire thickness of the skin, typically used for smaller areas where cosmetic appearance is crucial.

Epidermal skin graft (ESG):Only the outermost layer of the epidermis is harvested, often used for smaller wounds.

Considerations for Repair

1. Aesthetic Considerations: The face is a highly visible area, and any repair should aim to restore optimal aesthetic appearance. This may involve careful planning and execution of the repair to minimize scarring and ensure a natural-looking outcome.

2. Functional Considerations: In addition to aesthetic concerns, functional considerations are also crucial. The repair should aim to restore normal function to the affected area, particularly in critical areas such as the lips and eyelids.

3. Timing of Repair: The timing of repair is also important. In general, early repair is preferred to minimize the risk of complications and promote optimal healing.

Odontogenic Keratocyst (OKC)

The odontogenic keratocyst (OKC) is a unique and aggressive cystic lesion of the jaw with distinct histological features and a high recurrence rate. Below is a comprehensive overview of its characteristics, treatment options, and prognosis.

Characteristics of Odontogenic Keratocyst

1. Definition and Origin:

   • The term "odontogenic keratocyst" was first introduced by Philipsen in 1956. It is believed to originate from remnants of the dental lamina or basal cells of the oral epithelium.

2. Biological Behavior:

   • OKCs exhibit aggressive behavior and have a recurrence rate of 13% to 60%. They are considered to have a neoplastic nature rather than a purely developmental origin.

3. Histological Features:

   • The cyst lining is typically 6 to 10 cells thick, with a palisaded basal cell layer and a surface of corrugated parakeratin.
   • The epithelium may produce orthokeratin (10%), parakeratin (83%), or both (7%).
   • No rete ridges are present, and mitotic activity is frequent, contributing to the cyst's growth pattern.

4. Types:

   • Orthokeratinized OKC: Less aggressive, lower recurrence rate, often associated with dentigerous cysts.
   • Parakeratinized OKC: More aggressive with a higher recurrence rate.

5. Clinical Features:

   • Age: Peak incidence occurs in individuals aged 20 to 30 years.
   • Gender: Predilection for males (approximately 1:5 male to female ratio).
   • Location: More commonly found in the mandible, particularly in the ramus and third molar area. In the maxilla, the third molar area is also a common site.
   • Symptoms: Patients may be asymptomatic, but symptoms can include pain, soft-tissue swelling, drainage, and paresthesia of the lip or teeth.

6. Radiographic Features:

   • Typically appears as a unilocular lesion with a well-defined peripheral rim, although multilocular varieties (20%) can occur.
   • Scalloping of the borders is often present, and it may be associated with the crown of a retained tooth (40%).

Treatment Options for Odontogenic Keratocyst

1. Surgical Excision:

   • Enucleation: Complete removal of the cyst along with the surrounding tissue.
   • Curettage: Scraping of the cyst lining after enucleation to remove any residual cystic tissue.

2. Chemical Cauterization:

   • Carnoy’s Solution: Application of Carnoy’s solution (6 ml absolute alcohol, 3 ml chloroform, and 1 ml acetic acid) after enucleation and curettage can help reduce recurrence rates. It penetrates the bone and can assist in freeing the cyst from the bone wall.

3. Marsupialization:

   • This technique involves creating a window in the cyst to allow for drainage and reduction in size, which can be beneficial in larger cysts or in cases where complete excision is not feasible.

4. Primary Closure:

   • After enucleation and curettage, the site may be closed primarily or packed open to allow for healing.

5. Follow-Up:

   • Regular follow-up is essential due to the high recurrence rate. Patients should be monitored for signs of recurrence, especially in the first few years post-treatment.

Prognosis

• The prognosis for OKC is variable, with a significant recurrence rate attributed to the aggressive nature of the lesion and the potential for residual cystic tissue.
• Recurrence is not necessarily related to the size of the cyst or the presence of satellite cysts but is influenced by the nature of the lesion itself and the presence of dental lamina remnants.
• Multilocular lesions tend to have a higher recurrence rate compared to unilocular ones.
• Surgical technique does not significantly influence the likelihood of relapse.

Associated Conditions

• Multiple OKCs can be seen in syndromes such as:
  • Nevoid Basal Cell Carcinoma Syndrome (Gorlin-Goltz Syndrome)
  • Marfan Syndrome
  • Ehlers-Danlos Syndrome
  • Noonan Syndrome

Champy Technique of Fracture Stabilization

The Champy technique, developed by Champy et al. in the mid-1970s, is a method of fracture stabilization that utilizes non-compression monocortical miniplates applied as tension bands. This technique is particularly relevant in the context of mandibular fractures and is based on biomechanical principles that optimize the stability and healing of the bone.

Key Principles of the Champy Technique

1. Biomechanical Considerations:

   • Tensile and Compressive Stresses: Biomechanical studies have shown that tensile stresses occur in the upper border of the mandible, while compressive stresses are found in the lower border. This understanding is crucial for the placement of plates.
   • Bending and Torsional Forces: The forces acting on the mandible primarily produce bending movements. In the symphysis and parasymphysis regions, torsional forces are more significant than bending moments.

2. Ideal Osteosynthesis Line:

   • Champy et al. established the "ideal osteosynthesis line" at the base of the alveolar process. This line is critical for the effective placement of plates to ensure stability during the healing process.
   • Plate Placement:
     • Anterior Region: In the area between the mental foramina, a subapical plate is placed, and an additional plate is positioned near the lower border of the mandible to counteract torsional forces.
     • Posterior Region: Behind the mental foramen, the plate is applied just below the dental roots and above the inferior alveolar nerve.
     • Angle of Mandible: The plate is placed on the broad surface of the external oblique ridge.

3. Tension Band Principle:

   • The use of miniplates as tension bands allows for the distribution of forces across the fracture site, enhancing stability and promoting healing.

Treatment Steps

1. Reduction:

   • The first step in fracture treatment is the accurate reduction of the fracture fragments to restore normal anatomy.

2. Stabilization:

   • Following reduction, stabilization is achieved using the Champy technique, which involves the application of miniplates in accordance with the biomechanical principles outlined above.

3. Maxillomandibular Fixation (MMF):

   • MMF is often used as a standard method for both reduction and stabilization, particularly in cases where additional support is needed.

4. External Fixation:

   • In cases of atrophic edentulous mandibular fractures, extensive soft tissue injuries, severe communication, or infected fractures, external fixation may be considered.

Classification of Internal Fixation Techniques

• Absolute Stability:

  • Rigid internal fixation methods, such as compression plates, lag screws, and the tension band principle, fall under this category. These techniques provide strong stabilization but may compromise blood supply to the bone.

• Relative Stability:

  • Techniques such as bridging, biologic (flexible) fixation, and the Champy technique are classified as relative stability methods. These techniques allow for some movement at the fracture site, which can promote healing by maintaining blood supply to the cortical bone.

Biologic Fixation

• New Paradigm:
  • Biologic fixation represents a shift in fracture treatment philosophy, emphasizing that absolute stability is not always beneficial. Allowing for some movement at the fracture site can enhance blood supply and promote healing.
• Improved Blood Supply:
  • Not pressing the plate against the bone helps maintain blood supply to the cortical bone and prevents the formation of early temporary porosity, which can be detrimental to healing.

Fluid Resuscitation in Emergency Care

Fluid resuscitation is a critical component of managing patients in shock, particularly in cases of hypovolemic shock due to trauma, hemorrhage, or severe dehydration. The goal of fluid resuscitation is to restore intravascular volume, improve tissue perfusion, and stabilize vital signs. Below is an overview of the principles and protocols for fluid resuscitation.

Initial Fluid Resuscitation

1. Bolus Administration:

   • Adults: Initiate fluid resuscitation with a 1000 mL bolus of Ringer's Lactate (RL) or normal saline.
   • Children: Administer a 20 mL/kg bolus of RL or normal saline, recognizing that children may require more careful dosing based on their size and clinical condition.

2. Monitoring Response:

   • After the initial bolus, monitor the patient’s response to therapy using clinical indicators, including:
     • Blood Pressure: Assess for improvements in systolic and diastolic blood pressure.
     • Skin Perfusion: Evaluate capillary refill time, skin temperature, and color.
     • Urinary Output: Monitor urine output as an indicator of renal perfusion; a urine output of at least 0.5 mL/kg/hour is generally considered adequate.
     • Mental Status: Observe for changes in consciousness, alertness, and overall mental status.

Further Resuscitation Steps

1. Second Bolus:

   • If there is no transient response to the initial bolus (i.e., no improvement in blood pressure, skin perfusion, urinary output, or mental status), administer a second bolus of fluid (1000 mL for adults or 20 mL/kg for children).

2. Assessment of Ongoing Needs:

   • If ongoing resuscitation is required after two boluses, it is likely that the patient may need transfusion of blood products. This is particularly true in cases of significant hemorrhage or when there is evidence of inadequate perfusion despite adequate fluid resuscitation.

3. Transfusion Considerations:

   • Indications for Transfusion: Consider transfusion if the patient exhibits signs of severe anemia, persistent hypotension, or ongoing blood loss.
   • Type of Transfusion: Depending on the clinical scenario, packed red blood cells (PRBCs), fresh frozen plasma (FFP), or platelets may be indicated.