Área Clínica Médica - 5º año: Enfermedades más prevalentes del Sistema Nervioso Periférico

New Section

In this section, the speaker introduces the topic of peripheral nervous system diseases and provides an overview of the anatomical structures involved.

Anatomical Structures of the Peripheral Nervous System

• The peripheral nervous system comprises motor and sensory roots, spinal nerves, cranial nerves (excluding the first two pairs), sensory ganglia, and motor and sensory nerve endings.

• Neuropathy is a general term indicating dysfunction in the peripheral nervous system, with causes ranging from infectious to metabolic factors.

• Clinical presentation of neuropathy includes motor changes like weakness or paralysis, sensory alterations such as numbness or pain, and autonomic symptoms like orthostatic hypotension.

New Section

This part delves into key questions to consider when evaluating a patient with suspected neuropathy.

Key Questions for Evaluating Neuropathy

• Determine which system is affected: motor, sensory, autonomic, or a combination.

• Assess the distribution of symptoms—whether they are distal, proximal, or both—and inquire about sensory involvement.

• Consider the temporal evolution of symptoms to categorize neuropathy as acute (within four weeks), subacute (four to eight weeks), or chronic (over eight weeks).

New Section

This segment focuses on further diagnostic considerations and classification of neuropathies based on nerve involvement.

Diagnostic Considerations and Classification

• Investigate family history for neuropathies or related conditions to explore potential hereditary factors.

• Differentiate between mononeuropathy (involving a single nerve) and polyneuropathy (affecting multiple nerves).

• Classify neuropathies based on factors like type of neuron involved (motor/sensory/autonomic), time course (acute/subacute/chronic), location (single/multiple nerves), and symmetry/asymmetry.

Proximal Weakness and Guillain-Barre Syndrome

The medical evaluation of a patient presenting with proximal weakness and a history of recent illness, leading to considerations of Guillain-Barre Syndrome.

Patient Presentation and History

• The patient had weakness in both lower limbs following a fall after experiencing weakness upon waking up.

• Ten days before admission, the patient had a one-and-a-half-day episode of diarrhea. Physical examination revealed quadriparesis in the upper limbs and weakness in the lower limbs.

Clinical Assessment and Diagnosis

• The patient exhibited quadriparesis with varying strength levels in different muscle groups.

• Symptoms progressed from sensory issues to motor deficits, indicating peripheral nervous system involvement.

Differential Diagnosis: Guillain-Barre Syndrome

• Considering an acute polyneuropathy due to prior infection, Guillain-Barre Syndrome is a primary diagnostic consideration.

• Guillain-Barre Syndrome manifests as ascending paralysis starting from the feet, potentially linked to autoimmune processes.

Clinical Features and Diagnostic Considerations

Exploring the clinical features, progression patterns, and diagnostic criteria for Guillain-Barre Syndrome.

Clinical Presentation Variability

• While classically starting in the feet and progressing upwards (caudal to cranial), presentations can vary with upper limb involvement or isolated limb weaknesses.

Diagnostic Clues

• Symmetrical weakness with sensory-motor progression suggests peripheral nervous system involvement like in Guillain-Barre Syndrome.

• Presence of reduced reflexes alongside preserved superficial sensation aids in diagnosing this condition.

Complications and Risk Factors

Discussing potential complications, associated risk factors, and key considerations when evaluating patients for Guillain-Barre Syndrome.

Complications and Prevalence

• Autonomic dysfunction poses life-threatening risks such as cardiac arrhythmias or urinary retention in patients with Guillain-Barre Syndrome.

Risk Factors and Associations

• Infections like Campylobacteriosis or viral illnesses may precede Guillain-Barre Syndrome onset. Vaccinations or prior infections should be considered during diagnosis.

Pathophysiology Insights

Understanding Guillain-Barré Syndrome

In this section, the speaker discusses the formation of a membrane attack complex on cell surfaces, leading to vacuolar degeneration and inflammatory damage. The focus shifts to diagnosing Guillain-Barré syndrome through clinical evaluation and complementary methods like lumbar puncture.

Formation of Membrane Attack Complex

• The formation of a membrane attack complex on cell surfaces initiates vacuolar degeneration and perpetuates inflammatory damage.

Diagnosis of Guillain-Barré Syndrome

• Complementary methods for diagnosis include general laboratory tests like erythrocyte sedimentation rate and transaminase levels.

• Lumbar puncture is crucial for diagnosing the disease, analyzing cerebrospinal fluid for physical and chemical properties such as protein levels (proteinorrachia) and glucose levels (glucorrachia).

Importance of Lumbar Puncture Findings

• Normal values for cerebrospinal fluid parameters include up to 10 mononuclear elements and proteins up to 0.45 g/liter.

• Abnormal findings in lumbar puncture, such as elevated protein levels with normal cell count, indicate a dissociation that raises diagnostic doubts.

Diagnostic Tools for Guillain-Barré Syndrome

This segment delves into additional diagnostic tools like electromyography, emphasizing its availability in specialized centers post-onset. Clinical suspicion supported by neurological examination and lumbar puncture aids in accurate diagnosis.

Role of Electromyography

• Electromyography serves as a vital diagnostic tool but may not be immediately available in acute settings; it reveals demyelinating patterns indicative of nerve damage.

Clinical Suspicion and Neurological Examination

• Clinical suspicion backed by thorough neurological examination alongside lumbar puncture helps establish a diagnosis or high suspicion without immediate access to electromyography.

Treatment Strategies for Guillain-Barré Syndrome

Treatment considerations for Guillain-Barré syndrome encompass respiratory support due to potential complications, highlighting the need for intensive care monitoring from onset. Therapeutic options like plasma exchange or immunoglobulin administration aim to expedite recovery and reduce ventilator dependency.

Respiratory Support and Intensive Care

• Patients with Guillain-Barré syndrome require close monitoring in intermediate or intensive care units due to respiratory compromise or hemodynamic instability.

Therapeutic Interventions

• Plasma exchange or immunoglobulin therapy can accelerate recovery and decrease ventilator dependence; both treatments exhibit similar efficacy based on center preference rather than superiority.

Patient Progression & Management

Tracking patient progress post-treatment initiation reveals sensory improvement within a week followed by motor enhancement around two weeks. Discharge planning involves rehabilitation criteria following successful management of Guillain-Barré syndrome symptoms.

Post-Treatment Progression

• Patient response includes initial swallowing difficulty post-immunoglobulin dosing, evolving into sensory improvements after treatment completion, with motor enhancements appearing later.

Discharge Planning

Detailed Overview of Neuropathy Disorders

In this section, the speaker discusses various clinical variants of neuropathy disorders, focusing on specific syndromes and their characteristics.

Syndrome Variants and Characteristics

• The Miller Fisher syndrome is characterized by a triad of symptoms: ophthalmoparesis or ophthalmoplegia leading to diplopia, ataxia, and areflexia without muscle weakness. This triad is distinctive and indicative of the syndrome's presence.

• Another variant, Guillain-Barre axonal syndrome, involves an immune attack directed at the axon rather than myelin. It presents in two clinical forms: acute sensory-motor axonal and acute motor axonal.

• Moving on to diabetic neuropathy, it is highlighted as a significant cause of neuropathy. Approximately 10% of diabetic patients are assumed to have neuropathy at diagnosis, with subclinical cases escalating to 40% after ten years.

Understanding Diabetic Neuropathy: Prevalence and Pathophysiology

This segment delves into the prevalence and pathophysiology of diabetic neuropathy, emphasizing its impact on peripheral nervous system function.

Prevalence and Impact

• Diabetic neuropathy is noted as the most common form of neuropathy in the speaker's region. Its prevalence increases over time post-diabetes diagnosis, reaching up to 70-80% when diagnosed using electrodiagnostic criteria.

• Detecting diabetic neuropathy early is crucial due to its strong association with ulceration risk, infections, and subsequent amputations. Timely identification can significantly impact patient quality of life and mortality risk.

Pathophysiological Mechanisms Underlying Diabetic Neuropathy

The discussion shifts towards exploring various proposed theories explaining the pathophysiology of diabetic neuropathy.

Proposed Pathophysiological Mechanisms

• Several theories are presented regarding diabetic neuropathy pathogenesis. These include the polyol pathway involving sorbitol production impacting cellular potentials and alterations in sodium-potassium ATPase activity.

• Additionally, advanced glycation end products (AGEs) formation is highlighted as a key contributor to microvascular complications through myelin protein digestion. This process affects axonal proteins like tubulin and neurofilaments.

Factors Influencing Neuropathy Development in Diabetes Patients

Factors influencing the development of neuropathies in diabetic patients are discussed in this part.

Risk Factors

• Poor metabolic control, smoking habits, dyslipidemia, hypertension, along with disease duration exceeding ten years elevate the risk for developing diabetic neuropathies significantly.

• Various factors such as reduced blood flow leading to ischemia contribute to nerve damage in diabetes patients. Oxidative stress plays a role alongside deficiencies in vitamin E and autoimmune processes affecting vascular responses.

Neuropathy in Diabetic Patients

The discussion focuses on various aspects of neuropathy in diabetic patients, including its presentation, treatment options, and prevalence.

Proximal Weakness and Neuropathic Pain

• Proximal weakness can be bilateral or unilateral but often slightly asymmetric. It is a form of acute neuropathy that may recover spontaneously but often requires treatment due to severe pain.

Autonomic Neuropathy in Diabetic Patients

• Autonomic neuropathy is common in diabetic patients, with symptoms such as orthostatic hypotension, gastrointestinal issues (diarrhea/constipation), impotence, and bladder dysfunction.

Epidemiology and Manifestations of Autonomic Neuropathy

• Autonomic neuropathy prevalence is significant in insulin-dependent patients. Manifestations include cardiovascular, gastrointestinal, urogenital issues, thermoregulatory dysfunction, and pupillary dysfunction.

Orthostatic Hypotension and Diagnostic Considerations

• Orthostatic hypotension can lead to dizziness, blurred vision, or syncope. Diagnosis involves a drop of 20 mmHg systolic or 10 mmHg diastolic upon standing up.

Cardiac Autonomic Denervation Syndrome

• Cardiac autonomic denervation syndrome results in abnormal cardiac regulation leading to exercise intolerance, sudden death risk during anesthesia, and potential cardiomyopathy development.

Gastrointestinal Manifestations of Autonomic Neuropathy

This section delves into the gastrointestinal manifestations of autonomic neuropathy in diabetic patients.

Gastric Emptying Issues

• Autonomic neuropathy affects gastric motility leading to delayed gastric emptying. Symptoms include fullness after meals, nausea, vomiting, glycemic fluctuations, and weight loss.

Treatment Approaches for Gastrointestinal Symptoms

• Management includes fiber-rich diets or medications like Metoclopramide for improved gastric motility. Severe cases may require Alpha-adrenergic drugs for fecal incontinence.

Urogenital Complications in Diabetic Patients

This part discusses urogenital complications commonly seen in diabetic individuals due to autonomic neuropathy.

Bladder Dysfunction

• Urogenital manifestations include reduced bladder sensation leading to incomplete voiding (neurogenic bladder). This condition can progress to overflow urinary retention requiring interventions like catheterization.

Sexual Dysfunction and Management Strategies

Neuropathy in Diabetes

The discussion delves into the multifactorial nature of neuropathy in diabetes, exploring factors such as vascular, neurotrophic, metabolic dysregulation, and potential adverse effects of medications used for diabetes management.

Factors Contributing to Neuropathy in Diabetes

• Neuropathy in diabetes is three times more prevalent than in the general population due to a combination of vascular, neurotrophic, metabolic dysregulation factors. Adverse effects of diabetic medications can also play a role.

• Treatment involves addressing various factors: modifying responsible medications if identified, providing psychological counseling, and considering sildenafil at doses of 50-100 mg for diabetic patients.

• Diabetic patients may experience dysfunction in thermoregulation due to decreased or absent sweating in the feet leading to compensatory hyperhidrosis on the trunk and face. This loss of thermoregulation can significantly impact physical activities like exercise.

Management Strategies for Diabetic Neuropathy

• Effective management includes strict glycemic control to prevent neuropathy progression and addressing pain or sensory symptoms promptly as they can severely impact daily life. Various drugs like carbamazepine, pregabalin, amitriptyline are utilized for neuropathic pain treatment.

Neuropathy Overview

In this section, the speaker discusses neuropathies associated with motor neuron diseases and autoimmune bases.

Neuropathy Types and Diagnosis

• Motor neuron disease neuropathy primarily affects individuals over 50, especially males, presenting with progressive weakness, atrophy, fasciculations, and reflex loss.

• Autoimmune-based neuropathies target nerves like the ulnar, median, and radial nerves. Diagnosis involves anti-ganglioside antibodies testing alongside clinical symptoms.

• Diagnosis includes electrodiagnostic tests like electromyography to detect motor nerve conduction blocks and denervation in chronic cases.

Treatment and Management

• Immunoglobulin therapy shows significant efficacy in treating neuropathies. Refractory cases may require immunosuppressive drugs like cyclophosphamide or rituximab.

• Chronic alcohol-related neuropathy is prevalent after diabetic neuropathy. It manifests as sensory-motor chronic neuropathy due to direct toxic effects on nerve cells or vitamin deficiencies.

Facial Nerve Pathology

This part delves into facial nerve anatomy and common pathologies such as peripheral facial paralysis.

Facial Nerve Anatomy

• The facial nerve originates from the brainstem's lower protuberance, forming a loop around the abducens nucleus before emerging through the stylomastoid foramen.

• Understanding the superior and inferior motor nuclei of the facial nerve is crucial for comprehending supranuclear versus infranuclear lesions' clinical differences.

Clinical Examination and Paralysis

• The facial nerve innervates facial muscles involved in expressions. Clinical examination includes assessing symmetry, wrinkles, tear production, eyelid size changes, lip deviation, and muscle contractions.

Supratentorial Lesions and Facial Paralysis

In this section, the speaker discusses how supratentorial lesions can affect facial nerves asymmetrically, leading to distinct patterns of facial paralysis based on the location of the lesion.

Supratentorial Lesions and Facial Nerve Impact

• Supratentorial lesions can cause asymmetrical effects on facial nerves.

• Central involvement results in upper face mobility preservation but lower face compromise.

• Distinguishing central from peripheral facial paralysis is crucial in diagnosis.

• Peripheral facial paralysis may present with ear pain before onset.

• Understanding anatomy aids in diagnosing peripheral facial paralysis.

Treatment Approaches for Peripheral Facial Paralysis

This segment delves into the treatment strategies for peripheral facial paralysis, emphasizing medication, eye care, and rehabilitation.

Treatment Strategies

• Medication involves corticosteroids for early intervention.

• Vitamin B complex supplements are used alongside corticosteroids.

• Antiviral medications like acyclovir may be considered cautiously.

• Eye care includes artificial tears and nighttime eye protection.