Diaphragmatic Function and Phrenic Nerve Anatomy

Phrenic Nerves and Diaphragmatic Function

• Each hemidiaphragm receives supply from its own phrenic nerve.
• Phrenic nerves originate from the spinal cord at level C3 to C5.
• Phrenic nerves descend through the mediastinum, accompanying the great vessels of the chest and pericardium.

Consequences of Phrenic Nerve Damage

• Damage to or interruption of a phrenic nerve leads to paralysis of the ipsilateral hemidiaphragm.

Causes of Unilateral Diaphragmatic Paralysis

• Trauma is a possible cause of unilateral diaphragmatic paralysis.
• Brachial plexus injury can also lead to unilateral diaphragmatic paralysis.
• Inflammation can cause unilateral diaphragmatic paralysis.
• Cardiac surgery is a possible cause of unilateral diaphragmatic paralysis.
• In many cases, the cause of unilateral diaphragmatic paralysis is idiopathic (unknown).

Types of Brain Injury

• Brain injuries, including traumatic brain injury, stroke, and intracranial hemorrhage, can lead to respiratory failure through various mechanisms, commonly due to failure to protect the airway, often associated with a decreased level of consciousness.

Traumatic Brain Injury

• Caused by a violent blow or jolt to the head or body, or by an object penetrating brain tissue, such as a bullet or shattered piece of skull.
• Classified into mild and severe types, with mild cases affecting brain cells temporarily, and severe cases resulting in bruising, torn tissues, bleeding, and physical damage to the brain.
• Can result in long-term complications or death.

Stroke

• Occurs when blood flow to the brain is blocked or there is sudden bleeding in the brain.
• Types of strokes:

Ischemic Stroke

• Occurs when blood flow to the brain is blocked.

Hemorrhagic Stroke

• Occurs due to sudden bleeding in the brain.