Neuropathies, or damage to peripheral nerves, are a common and important topic in clinical medicine, frequently tested in exams like the PLAB. This module will cover the essential knowledge required to diagnose and manage various neuropathic conditions, focusing on UK guidelines and advanced clinical reasoning.

Peripheral neuropathies are conditions that affect the nerves outside of the brain and spinal cord (the peripheral nervous system). These nerves transmit signals between the central nervous system and the rest of the body, controlling everything from muscle movement to sensation and organ function. Damage to these nerves can lead to a wide range of symptoms.

Understanding the common causes is key to diagnosis. Diabetes mellitus is by far the most frequent cause of peripheral neuropathy, typically presenting as a distal symmetric sensory neuropathy.

Other significant causes include vitamin deficiencies (especially B12), alcohol abuse, autoimmune diseases (like Guillain-Barré Syndrome - GBS), infections (e.g., HIV, Lyme disease), and certain medications (e.g., chemotherapy agents).

Certain neuropathic syndromes are particularly important for PLAB preparation due to their distinct clinical features and management protocols.

Characterized by progressive sensory loss, often starting in the feet. Painful neuropathies can cause burning, shooting pains, and allodynia (pain from non-painful stimuli). Autonomic involvement can lead to gastroparesis, erectile dysfunction, and orthostatic hypotension.

An acute, rapidly progressive, symmetrical motor weakness, often ascending. Sensory symptoms can occur, and autonomic dysfunction is common. It's an autoimmune disorder triggered by an infection. Management involves supportive care and immunomodulatory treatments (IVIg or plasma exchange).

A chronic counterpart to GBS, characterized by progressive or relapsing motor and sensory deficits over months to years. It is also an autoimmune demyelinating neuropathy, often responding to immunosuppressive therapies.

A thorough history and physical examination are paramount. Key elements include the onset, progression, distribution of symptoms, and associated medical conditions. Investigations aim to identify the underlying cause.

Essential investigations include: Blood tests (FBC, U&Es, LFTs, HbA1c, B12, folate, thyroid function, ESR/CRP, autoimmune markers), Nerve Conduction Studies (NCS) and Electromyography (EMG) to differentiate axonal vs. demyelinating patterns and assess severity, and sometimes nerve biopsy for specific cases.

Management focuses on treating the underlying cause, managing symptoms, and preventing complications. UK guidelines emphasize a holistic approach.

For inflammatory neuropathies like GBS and CIDP, prompt diagnosis and treatment with immunomodulatory therapies (IVIg or plasma exchange) are crucial to improve outcomes and reduce disability. Supportive care, including respiratory monitoring and physiotherapy, is vital.

The prognosis varies greatly depending on the cause and severity. Early diagnosis and appropriate management can significantly improve outcomes and prevent long-term disability. Complications can include falls due to sensory loss and motor weakness, chronic pain, and autonomic dysfunction leading to significant morbidity.