ENTRAPMENT NEUROPATHIES – PPT (Downloadable)

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Entrapment Neuropathies

Definition: Entrapment neuropathies involve pressure-induced injury to a peripheral nerve due to anatomical or pathological structures. These conditions can have significant physical, psychological, and economic impacts.

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Pathophysiology:

• Intrinsic abnormalities in nerves, like diabetic neuropathy or autoimmune neuritis, can cause nerve swelling or decreased tolerance to compression.
• Inflammation or edema in surrounding structures can reduce the nerve’s passageway, leading to compression.
• Compression disrupts the blood-nerve barrier, causing ischemia and edema, with large fibers being more vulnerable than small fibers.

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Common Types and Features:

1. Median Nerve Entrapment (Carpal Tunnel Syndrome – CTS):
   • Affects 3% of women and 2% of men, with higher prevalence in women over 55.
   • Symptoms include pain, paresthesia in the median nerve distribution, and nocturnal numbness.
   • Caused by increased pressure within the carpal tunnel, leading to endoneurial edema, demyelination, and axonal degeneration.
2. Ulnar Nerve Entrapment:
   • Second most common entrapment neuropathy, often occurring at the elbow.
   • Diagnosis involves motor conduction studies showing velocities below 50 m/sec.
   • Imaging, such as T2-weighted MRI, may reveal increased signal intensity.
3. Common Peroneal Nerve Entrapment:
   • Most frequently injured nerve in the lower extremity, involved in 25% of traumatic peripheral nerve injuries.
   • Diagnostic tests include electromyography of both peroneal and non-peroneal muscles to exclude other causes.
4. Posterior Tibial Nerve Entrapment (Tarsal Tunnel Syndrome – TTS):
   • Caused by bony impingement or lesions compressing the nerve in the tarsal tunnel.
   • Symptoms include burning foot pain and positive Tinel sign.
   • Diagnosis involves prolonged latency or slowed conduction in nerve studies.
5. Double Crush Syndrome:
   • Coexistence of compressive lesions in series along a nerve, such as cervical radiculopathy and CTS.
6. Thoracic Outlet Syndrome (TOS):
   • Affects the brachial plexus and associated cervical and thoracic nerves.
   • May involve pain in the fourth and fifth digits and motor deficits in the hand.
7. Brachial Plexus Entrapment:
   • Often caused by compression at the scalene triangle, presenting with hand pain and muscle weakness.
8. Scalene Syndrome:
   • Commonly caused by whiplash or sports injuries.
   • May require image-guided injections for treatment.

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Diagnostic Methods:

• Electrophysiologic studies (e.g., motor conduction velocities).
• Imaging techniques like MRI and ultrasonography.
• Electromyography to differentiate between nerve lesions and other conditions.

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Treatment Approaches:

• Non-invasive treatments include physical therapy and ergonomic adjustments.
• Invasive options include nerve decompression surgeries and image-guided injections (e.g., scalene injections).
• Neuroplasty, using approaches like supraclavicular or transaxillary methods, is employed in complex cases like TOS.