Approach to the Patient with Neurologic Disease¶
Chapter 433 | Part 13: Neurologic Disorders
KEY CLINICAL POINTS¶
- Prioritize history and physical examination over costly imaging/laboratory tests for neurologic diagnosis.
- Systematically localize the lesion anatomically (CNS vs PNS, specific regions) before determining pathophysiology.
- Use standardized tools like the MMSE for cognitive assessment and structured neurologic exams for accurate localization.
- Distinguish between transient (TIA) and persistent neurologic deficits to guide urgent vs. non-urgent management.
- Integrate clinical findings with imaging, lab tests, and electrophysiologic studies for etiologic diagnosis.
1. DEFINITION & OVERVIEW¶
Neurologic disorders are common, costly, and leading causes of disability/death globally. Modern therapies require precise diagnosis through a structured approach emphasizing history, physical exam, and judicious use of imaging. The neurologic method involves: (1) defining anatomical location, (2) identifying pathophysiology, and (3) formulating a differential diagnosis.
1.1 Neurologic Method¶
The method ensures efficient diagnosis by first localizing the lesion (CNS vs PNS, specific regions), then determining the pathophysiology (e.g., demyelination, ischemia), and finally considering etiologies. This approach prevents diagnostic errors and enables timely treatment.
1.2 Key Components¶
The approach includes: (1) patient history (symptoms, temporal course, family history), (2) physical examination (mental status, cranial nerves, motor/sensory systems), (3) targeted investigations (imaging, lab tests), and (4) integration of findings for etiologic diagnosis.
2. EPIDEMIOLOGY¶
Neurologic disorders affect ~1/3 of the global population, with rising prevalence due to aging, population growth, and metabolic risk factors. Key conditions include: - Stroke (42.2% of DALYs, 61.2% of deaths) - Alzheimer’s/dementia (10.4% DALYs, 26.4% deaths) - Traumatic brain injury (2.9% DALYs) - Spinal cord injury (3.5% DALYs) - Meningitis (7.9% DALYs) - Encephalitis (2.4% DALYs) - Brain tumors (2.8% DALYs) - Epilepsy (4.9% DALYs) - Parkinson’s disease (2.3% DALYs) - Multiple sclerosis (0.4% DALYs) - Motor neuron diseases (0.3% DALYs) - Tetanus (0.9% DALYs)
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Pathophysiology depends on lesion location: - Gray matter: Cognitive disturbances, movement disorders, seizures - White matter: Long tract signs (spasticity, sensory loss) - CNS: Demyelination (MS), ischemia, infection, tumors - PNS: Peripheral neuropathy, neuromuscular junction disorders (e.g., myasthenia gravis) - Vascular: Stroke, TIA, subarachnoid hemorrhage - Infectious: Meningitis, encephalitis, syphilis - Metabolic: Hypoglycemia, uremia, vitamin deficiencies - Toxic: Alcohol, drugs (e.g., vincristine), heavy metals - Genetic: Neurofibromatosis, Huntington’s, Charcot-Marie-Tooth
4. CLINICAL FEATURES¶
Symptoms vary by lesion location and etiology: - Acute onset: Stroke, TIA, seizures, migraine - Subacute: MS, infections, metabolic disorders - Chronic: Neurodegenerative diseases (e.g., Alzheimer’s), tumors - Key signs: - TIA: Transient focal deficits, no residual weakness - Seizures: Sudden onset, focal or generalized - Migraine: Headache with aura, visual disturbances - Spinal cord: Sensory level, sphincter dysfunction - Peripheral neuropathy: Stocking/glove distribution, areflexia
5. DIFFERENTIAL DIAGNOSIS¶
Differential diagnosis depends on presentation: - Focal deficits: Stroke, tumor, MS, brain abscess - Bilateral deficits: Metabolic encephalopathy, Wernicke’s encephalopathy - Seizures: Epilepsy vs. syncope vs. psychogenic non-epileptic attacks - Cognitive impairment: Dementia vs. delirium vs. depression - Migraine vs. TIA: Duration, pattern of symptoms, response to treatment - Infectious vs. inflammatory: Fever, CSF findings, response to antibiotics
6. INVESTIGATIONS & DIAGNOSIS¶
Diagnostic workup includes: 1. Initial tests: CBC, electrolytes, renal/liver function, glucose, LFTs, coagulation 2. Neuroimaging: MRI/CT for CNS lesions, MRA/CTA for vascular disease 3. CSF analysis: In suspected meningitis/encephalitis 4. Electrophysiologic studies: EMG/NCS for neuropathy 5. Specialized tests: Lumbar puncture, EEG, genetic testing, lumbar puncture 6. Algorithm: Use clinical findings to guide imaging (e.g., MRI for MS, CT for stroke) 7. Diagnostic criteria: Apply for conditions like MS (McDonald criteria), TIA (ABCDEF criteria)
7. MANAGEMENT & TREATMENT¶
Management depends on etiology: - Acute ischemic stroke: Thrombolysis (within 4.5h), antiplatelets, anticoagulation - TIA: Antiplatelet therapy, carotid endarterectomy, risk factor modification - Seizures: Anticonvulsants (e.g., levetiracetam), EEG monitoring - Infections: Targeted antibiotics/antivirals, CSF drainage - Neurodegenerative: Symptomatic treatment (e.g., levodopa for Parkinson’s) - Neoplasms: Surgery, radiation, chemotherapy - Toxic/metabolic: Correct underlying cause, supportive care - Rehabilitation: Physical therapy, occupational therapy, speech therapy
8. PROGNOSIS & COMPLICATIONS¶
Prognosis varies by condition: - Stroke: Mortality 10–30%, long-term disability common - MS: Relapsing-remitting course, progressive disability in 50% within 10 years - Alzheimer’s: Progressive decline, mortality 5–10 years post-diagnosis - TIA: 10% risk of stroke within 90 days - Complications: Secondary infections, falls, depression, cognitive decline - Monitoring: Regular follow-up for chronic conditions (e.g., hypertension, diabetes)
9. SPECIAL CONSIDERATIONS¶
Special populations require tailored approaches: - Pregnancy: Avoid teratogenic drugs (e.g., valproate), manage seizures with lamotrigine - Pediatrics: Suspect meningitis, metabolic disorders, congenital anomalies - Elderly: Higher risk of stroke, falls, and drug interactions - Neuroimmunology: Monitor for autoimmune encephalitis, paraneoplastic syndromes - Cancer patients: Neurotoxicity from chemotherapy, paraneoplastic syndromes
10. KEY POINTS & CLINICAL PEARLS¶
Clinical pearls: 1. History: Prioritize temporal course, symptom localization, and family history. 2. Examination: Use structured neurologic exams (e.g., MMSE, cranial nerves, coordination). 3. Differential diagnosis: Distinguish TIA vs. stroke, seizure vs. syncope. 4. Imaging: Use MRI for MS, CT for acute stroke, lumbar puncture for infections. 5. Management: Tailor treatment to etiology (e.g., anticoagulation for atrial fibrillation). 6. Follow-up: Monitor for complications and adjust therapy based on response.
Table 433-1: Findings for Nervous System Localization¶
| System | Key Signs |
|---|---|
| Cerebrum | Abnormal mental status, seizures, unilateral weakness, visual field defects |
| Brainstem | Isolated cranial nerve abnormalities, crossed weakness (e.g., right face/left arm), brainstem signs |
| Spinal Cord | Back pain, sensory level, sphincter dysfunction, mixed motor/sensory deficits |
| Peripheral Nerve | Radicular pain, nerve distribution weakness/sensory loss, loss of reflexes |
| Muscle | Bilateral proximal/distal weakness, sparing of sensation |
| Neuromuscular Junction | Bilateral weakness (e.g., ptosis, diplopia), increased fatigue with exertion |
| Cerebellum | Ataxia, dysmetria, intention tremor, truncal instability |
| Basal Ganglia | Parkinsonism (rigidity, bradykinesia, tremor), chorea, dystonia |