Penetrating Neck Trauma

Definition: Traumatic injury to the neck that penetrates the platysma

Definitive management of penetrating neck injuries, especially in stable patients, is a matter of debate → Zone-based vs No-zone approach

Applied Anatomy

• Injuries can be categorized into anatomical zones:
  1. Zone 1 → Clavicles to cricoid
  2. Zone 2 → Cricoid to angle of mandible
  3. Zone 3 → Angle of mandible to base of skull

Epidemiology

Penetrating neck trauma is seen in ~1% of all trauma cases

• ~1/3 of patients co-present with other injuries (polytrauma)

Frequency of presentation varies according to location

• UK < USA and South Africa

Zone 2 injuries are most common (Zone 2 > Zone 1 > Zone 3)

Clinical Features

Hard signs suggestive of injury to vital structures (HARD BRUIT)
Hypotension Arterial bleeding/Aerodigestive signs - Bubbling wound - Haemoptysis/Haematemesis) Rapid expanding haematoma Deficit (neurological or pulse) BRUIT (or thrill)
Soft Signs suggestive of injury to vital structures
Hoarse voice Stridor Subcutaneous emphysema

Signs are dependent on severity of injury to underlying structures:

• Hypotension
  • Vascular damage
  • Don’t forget that this can also be due to trauma elsewhere in the body
• Dysphagia
  • Oesophageal injury
• Hoarseness
  • Tracheal, laryngeal or peripheral nerve injury
• Neurological deficit
  • Spinal cord, peripheral nerve or vascular injury

Incidence of structures involved:

• Aerodigestive tract
  • Larynx/trachea – 10%
  • Pharynx/oesophagus – 9%
• Vascular
  • Internal jugular vein – 9%
  • Carotid – 7%
  • Subclavian artery – 2%
  • Vertebral artery – 1%
• Other
  • Spinal cord – 3%
  • Brachial plexus – 2%
  • CN IX and X – 1%

Aetiology and Pathogenesis

Aetiology:

Various mechanisms need to be considered (accidental and deliberate)

Commonly due to knives, guns and impaling objects

Pathogenesis:

Injuries can be divided into high- and low- velocity

Knives/impaling objects wielded by hand are low energy

Guns can be high- or low- velocity:

• Low velocity (handguns/airguns) – do not penetrate bone therefore their pathway through soft tissue is erratic and cause unpredictable injury to soft tissue
• High velocity (military/hunting rifles) – bullets follow a more direct and predictable course through soft and hard tissue. Entry and exit wounds can seem innocuous therefore giving a false sense of security

Important to consider projectile characteristics

• Different types of ammunition will affect the extent of tissue damage; mass, shape, design (e.g. "Hollow points")
• Penetrating object may cause damage to tissues directly or as a result of displacement and cavitation (i.e. structures adjacent to the path of a projectile)

Investigations

Assessment and interventions are usually carried out concomitantly as part of major trauma call

Vital signs may point towards haemorrhagic shock ("hard sign" of damage to underlying structures)

Unstable patients may require immediate surgical exploration - detailed investigation should not delay life saving intervention in this patient group

Laboratory Investigations

• Full blood count (establish baseline +/- need for transfusion)
• Group and save
• Toxicology screen
  • Particularly if altered consciousness
  • This is important to help differentiate the altered sensorium of intoxication from a neurologic aetiology following penetrating neck trauma with an arterial injury component
  • Also may be important for police investigation into cause of injury

Imaging

Plain film

• Plain neck or chest radiographs may show retropharyngeal air or pneumomediastinum suggesting oesophageal injury

Computed tomography (CT)

• Useful for penetration/missile tract
• Good for laryngeal injury
• Poor if lots of metallic foreign bodies due to scatter
• Water soluble contrast (e.g. gastrografin) can be used if oesophageal injury is suspected

CT Angiography (CTA)

• Gold standard for identifying arterial injury
• Digital subtraction angiography is the best

Magnetic Resonance Imaging (MRI)

• Too time consuming
• Risks of magnetic objects loose in the neck (overheating, dislodging)

Direct visualisation

• Laryngoscopyy
• Bronchoscopy
• Oesophagoscopy

Management

Resuscitation

Immediate management using ATLS principles with (C)ABCDE algorithm

Catastrophic haemorrhage can be seen with penetrating neck injury

Immediate life threats are exsanguination and asphyxiation from airway obstruction

Airway and cervical spine:

• Patients with hard signs need airway secured early
• Expanding haematomas, haematemesis, haemoptysis and palsies secondary to nerve injury compromise airway and complicate procedures
• Be prepared for cricothyroidotomy/tracheostomy if endotracheal tube placement fails
• Cervical spine precautions –
  • Only immobilise if mechanism of injury suggests spine involvement
  • Immobilisation may be unhelpful as it can obscure injuries, prevent adequate assessment and delay definitive airway

Breathing:

• Zone 1 or injuries traversing zones can cause pneumothorax
• Minimize bag valve mask as it can cause dissection of air into the neck worsening airway distortion

Circulation:

• Large-bore intravenous catheters for fluid resuscitation
• Initially target the mean arterial pressure of 50 mm Hg until definitive treatment of haemorrhage
• Higher BP can cause more bleeding
• If bleeding is catastrophic address this before airway as commonest cause of death
• Do not probe wounds that are actively bleeding (can dislodge clot)
• Direct pressure usually enough to control bleeding
• If direct pressure fails → insertion of a foley catheter and balloon inflation may be a temporary way to achieve tamponade of bleeding

Post-resuscitation Condsiderations

After the primary survey and resuscitation physical examination should focus on identification of any hard or soft signs associated with injury to important structures

Management is dependent on stability of patient

Patients with hard signs or haemodynamic instability need urgent surgical exploration

Definitive management of penetrating neck injuries, especially in stable patients, is a matter of debate → zone-based vs non-zoned approach

High rates of negative surgical explorations + improvements in diagnostic imaging (especially CT angiography) → many trauma centres prefer no-zone approach

Increased use of CT has also demonstrated that injuries with single entry point commonly traverse more than one zone ← further argument for a non-zoned approach

Zone-Based Approach

Based on location of the external wound

Approach formulated due to high mortality rates (35%) prior to World War II

Initially all penetrating neck injuries were explored surgically → this led to an unacceptably high negative exploration rates thus surgeons developed a zone-based approach

Zone-based algorithms have evolved but essentially:

• Zone 2 injuries → Either mandatory or low threshold for surgical exploration
• Zones 1 and 3 injuries → Further diagnostic studies are carried out prior to operative intervention

No-zone Approach

Based on patient stability and presence of soft versus hard signs of injury (regardless of location of wound)

Unstable patients → transferred rapidly to operating theatre

Stable but symptomatic patients → CT angiography + clinical examination to determine if further diagnostic studies, surgical intervention or both are needed

Concerns regarding the no-zone are due to limitations of CT angiography for detecting life-threatening pharyngeal and oesophageal injuries

Surgical exploration of the neck

Full article on Surgical Exploration of Neck Wounds

Postoperative management

Close monitoring and management of other injuries

Plan for ventilation wean

Barium swallow 1 week post injury to assess if oesophageal repair is intact

May require re-exploration if:

• Sepsis of unknown source
• Collection
• Haemorrhage

Tetanus prophylaxis usually needed as these are high risk wounds (Tetanus guidelines)

Antibiotic prophylaxis needed (gram-positive coverage)

Prognosis and Complications

Mortality of ~5% in both civilian and military populations

• Mortality varies according to zone - Zone 1 > Zone 3 > Zone 2 (highest in zone 1 possibly due to proximity to mediastinal structures)
• Exsanguination is the commonest cause of death (carotid is most commonly the culprit)

Presence of hard signs associated with 90% rate of major injury

Injuries may be missed initially and may result in:

• Persistent haemorrhage
  • Often from a missed arterial or venous injury, particularly in zone 1 and 3
• Pseudoaneurysms
• Dissections
• Fistulas
  • Oesophagocutaneous, oesophagotracheal, tracheocutaneous, venoarterial
• Infections
  • Most often occur from missed oesophageal or laryngotracheal injuries
  • May lead to:
  • Abscess formation
  • Mediastinitis
• Stenosis or obstruction of luminal structures
  • Results from inflammatory response and scarring around the injured structures
• Neurologic deficits
  • Results from:
  • direct peripheral nerve injury
  • ischemic infarct caused by arterial injury
• Anastomotic or repair disruption
  • About 1% of surgical repairs leak
  • Result in:
    • Haemorrhage
    • Infection
    • Fistula formation
• Massive air emboli
  • Major venous injuries may cause of bilateral, diffuse stroke