Cancer Staging and Surgical Procedures

Pain Pathways

• Pain is a subjective experience associated with tissue damage.
• The International Association for the Study of Pain defines pain as an unpleasant sensory and emotional experience.
• Pain involves a complex interaction of the ascending and descending nervous systems.
• Pain perception involves sensory, motivational, and cognitive levels.

Historical Definitions of Pain

• Aristotle considered pain as a feeling processed in the heart.
• Descartes, Galen, and Vesalius linked pain to brain processes.
• 19th-century physiologists identified sensory receptors and nociceptors.

Epidemiology of Pain

• Millions experience chronic pain in the US.
• Acute pain from injury or surgery is common.

Categories of Pain

• Nociceptive pain (somatic and visceral): originating from injury or tissue damage.
• Neuropathic pain (nerve damage or dysfunction).
• Inflammatory pain (inflammation).
• Psychogenic pain (psychological factors).
• Referred pain (pain felt in a location distant from the source).
• Phantom pain (pain felt in a limb that is no longer present).

Acute Pain

• Rapid onset, often associated with tissue damage.
• Usually brief and resolves with appropriate treatment.

Chronic Pain

• Persistent or recurring pain lasting three or more months.
• Often more complex to treat.

Pain Theories

• Specificity theory: distinct receptors and pathways transmit pain signals.
• Pattern theory: different patterns of neuronal activity distinguish pain and non-pain sensations.
• Neuromatrix theory: the brain plays a critical role in pain through a neural network (called the neuromatrix) integrating sensory, emotional, and cognitive factors to create the subjective experience of pain.
• Gate control theory: spinal cord mechanisms modulate pain signals.

Endogenous Analgesic Mechanisms

• The body produces its own opioid-like substances that can block or suppress pain signals.

Pain Pathways

• Pain signals travel through specific pathways from the periphery to the brain. These include A-beta fibres, A-delta fibres, and C fibres.

Third Order Neurons

• Neurons within the thalamus and reticular formation transmit pain signals to the cerebral cortex and areas dealing with emotions.

Ascending & Descending Pain Pathways

• Ascending pathways carry pain information from the periphery to higher brain centres.
• Descending pathways carry signals from the brain to influence pain perception in the spinal cord.

Pain Management Strategies

• Non-pharmacological (physiotherapy, relaxation techniques, psychological support)
• Pharmacological (opioids, nonopioids, adjuvant analgesics)
• Surgical approaches (cordotomy, rhizotomy).

Treatment Modalities

• Surgery
• Radiation therapy
• Chemotherapy
• Immunotherapy/Biologic Therapy
• Molecularly targeted therapy

Clinical Presentation of Pain

• Includes acute and chronic pain presentations.
• A thorough history, physical exam, and diagnostic tests are necessary.

Pain Assessment Tools

• Rating scales (verbal, numerical)
• Multi-dimensional assessment scales (McGill pain questionnaire).

Specific Cancer Pain

• Includes types of cancer, symptoms, and treatment options.

Types of Radiotherapy

• External radiation (teletherapy, intensity modulated RT)
• Internal radiation (brachytherapy, systemic internal radiation)

Effects of Radiotherapy

• Short-term and long-term effects on tissues and organs.
• Requires careful patient monitoring and management to alleviate symptoms.

Adverse Effects of Chemotherapy

• Includes common side effects of the treatment.
• Proper management includes early identification of the adverse effects and initiating the necessary actions to minimize the effects.

Management of Pain

• Needs a comprehensive approach including pharmacological and non-pharmacological interventions

Medical Management of Pain

• Requires a holistic approach encompassing both pharmacological and non-pharmacological considerations.

Tumor Lysis Syndrome (TLS)

• This describes a rapid breakdown of malignant tumor cells when undergoing aggressive therapies that can release metabolic products into the bloodstream.