What are the 100 essential secrets of neurology?

1. The first step in treating patients with neurologic disease is to localize the lesion.
2. Myopathies cause proximal symmetric weakness without sensory loss.
3. Neuromuscular junction diseases cause fatigability.
4. Peripheral neuropathies cause distal asymmetric weakness with atrophy, fasciculations, sensory loss, and pain.
5. Radiculopathies cause radiating pain.
6. Spinal cord disease causes a triad of distal symmetric weakness, sphincter problems, and a sensory level.
7. A unilateral lesion within the brain stem often causes “crossed syndromes,” in which ipsilateral dysfunction of one or more cranial nerves is accompanied by hemiparesis and/or hemisensory loss on the contralateral body.
8. Cerebellar disease causes ataxia and an action tremor.
9. In the brain, cortical lesions may cause aphasia, seizures, and partial hemiparesis (face and arm only), while subcortical lesions may cause visual field cuts, dense numbness of primary sensory modalities, and more complete hemiparesis (face, arm, and leg).
10. The brain is isolated from the rest of the body by the blood-brain barrier.
11. Learning and memory are possible because repetitive input to a synapse can cause persistent changes in neuronal function (long-term potentiation).
12. Some of the most common and important neurologic diseases are caused by abnormalities in neurotransmitters: Alzheimer’s (acetylcholine), epilepsy (γ-aminobutyric acid, GABA), Parkinson’s (dopamine), migraine (serotonin), and others.
13. Many genetic neurologic diseases have been shown to be caused by expansion of trinucleotide (triplet) repeat sequences.
14. Foot drop (weakness of the tibialis anterior muscle) can be caused by lesions to the common peroneal nerve or L5 nerve root.
15. If the facial nerve is damaged (such as from Bell’s palsy), the entire side of the face is weak. If the cortical input to the facial nerve is damaged (such as from a stroke), only the lower half of the face will be weak.
16. A dilated or “blown” pupil implies compression of the third cranial nerve. This is often due to a serious lesion such as an aneurysm or brain herniation.
17. Collateral blood flow, often routed through the circle of Willis, sometimes protects against damage from strokes.
18. Noncommunicating hydrocephalus is often a medical emergency because the obstructed cerebrospinal fluid (CSF) will cause the intracranial pressure to rise.
19. The diagnosis of myopathies often is based on serum creatine kinase (CK) levels, electromyography (EMG) findings, and muscle biopsy.
20. Myotonic dystrophy is the most common muscular dystrophy in adults.
21. The possibility of respiratory failure is the most serious concern in the management of most patients with myopathies or neuromuscular junction diseases.
22. Drug toxicity should always be considered in the differential diagnosis of many neurologic conditions.
23. Neuroleptic malignant syndrome is a true medical emergency with a high mortality.
24. Patients with myasthenia gravis show a decremental response (fatigue) with repetitive stimulation of their muscles.
25. Up to 40% of myasthenic patients experience a transient exacerbation after starting high-dose steroids, usually within 5 to 7 days.
26. Lambert-Eaton myasthenic syndrome (LEMS) resembles myasthenia gravis with autonomic dysfunction and arises from an autoimmune attack on presynaptic voltage-gated calcium channels.
27. Myotonia, a delayed relaxation after muscle contraction, is most common in muscular dystrophies but can be seen in a host of other conditions.
28. On an EMG, muscle disease shows full contraction of all muscles but with short, small motor units.
29. On an EMG, nerve disease shows a dropout and reduction in muscle contraction, with prolonged, large motor units. There may be fibrillations and fasciculations.
30. The most common causes of peripheral neuropathy are diabetes and alcoholism. 31. The most common motor neuropathy is Guillain-Barré syndrome.
31. Nerve biopsy is seldom necessary for the diagnosis of peripheral neuropathy.
32. The most often overlooked cause of peripheral neuropathy is genetic.
33. The spinal fluid of patients with Guillain-Barré syndrome has high protein but low (normal) cell counts.
34. The most common motor neuron disease is amyotrophic lateral sclerosis (ALS).
35. Indications for surgery in patients with radiculopathies are intractable pain, progressive motor weakness or sensory deficits, or symptoms refractory to a reasonable degree of nonoperative therapy.
36. Neurogenic claudication (pseudo claudication) presents typically as bilateral, asymmetric, lower extremity pain that is provoked by walking (occasionally standing) and relieved by rest.
37. Sudden damage to the spinal cord can cause spinal shock, which results in temporary flaccid paralysis, hyporeflexia, sensory loss, and loss of bladder tone.
38. Occlusion of the artery of Adamkiewicz may result in anterior spinal artery syndrome, causing bilateral weakness, loss of pain and temperature, and hyperreflexia below the lesion with preserved dorsal column functions (position and vibration).
39. Cauda equina syndrome is a neurosurgical emergency that presents with weakness and sensory loss in the lower extremities, prominent radicular pain, saddle anesthesia, and urinary incontinence. 41. Symptoms of brain stem ischemia are usually multiple, and isolated findings (such as vertigo or diplopia) are more often caused by peripheral lesions affecting individual cranial nerves.
40. Ménière’s disease presents with the symptomatic triad of episodic vertigo, tinnitus, and hearing loss. It is caused by an increased amount of endolymph in the Scala media. Pathologically, hair cells degenerate in the macula and vestibule.
41. The blood supply of the brain stem is derived from the vertebrobasilar system of the posterior circulation.
42. There are only two causes of coma: a process affecting the reticular activating system in the brain stem or a process affecting both cerebral hemispheres simultaneously.
43. Posterior fossa neoplasms account for 50% of the total number of neoplasms in children. In adults, they are much rarer.
44. Lesions of the cerebellar hemisphere impair movement on the ipsilateral side of the body because of a double-crossing of the pathways.
45. Loss of pigmented dopaminergic neurons in the substantia nigra is the pathologic hallmark of Parkinson’s disease.
46. Sinemet (levodopa) remains the most valuable therapy for Parkinson’s disease. 49. Essential tremor is the most common cause of tremor.
47. Torticollis is the most common form of focal dystonia.
48. Botulinum toxin is the treatment of choice for most focal dystonias.
49. Tardive dyskinesia is a serious side effect of many neuroleptic drugs.
50. Cardinal symptoms of autonomic insufficiency include orthostatic hypotension, bowel and bladder dysfunction, impotence, and sweating abnormalities.
51. Diabetic neuropathy is one of the most common causes of autonomic dysfunction.
52. Syncope is seldom a neurologic problem; loss of consciousness is almost always due to cardiovascular disease.
53. Traditionally, the diagnosis of multiple sclerosis requires two separate symptoms at two different times, or lesions disseminated in time and space.
54. Faulty interpretation of magnetic resonance imaging (MRI) scans is the most common error in misdiagnosing multiple sclerosis.
55. No treatment has yet been shown to prevent ultimate disability in multiple sclerosis.
56. Dementia must be differentiated from delirium and depression.
57. Dementia is a category, not a diagnosis. The clinician must determine the cause of dementia.
58. Seizures that persist or recur without regaining consciousness are called status epilepticus. To avoid permanent brain damage, these should be stopped within 1 hour of onset.
59. Alzheimer’s disease and other dementias are treatable. Both cognitive and behavioral symptoms can be treated, and long-term therapy may slow decline and help maintain function.
60. Vascular dementia cannot be diagnosed by MRI or computed tomography (CT) scan alone. It also requires a clinical picture of cerebral ischemia.
61. A common cause of excessive daytime sleepiness is obstructive sleep apnea syndrome.
62. A patient’s own assessment of his sleep quantity and quality is often unreliable. Polysomnographic evaluation (sleep laboratory testing) is the only reliable means for obtaining objective information regarding a suspected sleep disturbance.
63. The classic tetrad of narcolepsy is excessive daytime sleepiness, cataplexy, sleep paralysis, and hypnagogic hallucinations.
64. Gliomas are the most common primary brain tumors.
65. Astrocytomas are the most common spinal cord tumors.
66. Metastatic brain tumors are 10 times more common than primary brain tumors.
67. Cancer that metastasizes to the spine usually causes pain, a sensory level, paraplegia, and sphincter disturbances. It is usually treated by radiation therapy.
68. Many cancer patients die in pain because physicians fail to treat pain appropriately.
69. Dysarthria is a defect in the way speech sounds, which can arise from many causes, whereas aphasia is a defect in the use of language and results from damage to the dominant (usually left) cerebral cortex.
70. Antibiotics should be given immediately to patients with meningitis and not delayed while other tests are performed.
71. Mad cow disease is a variant of Creutzfeldt-Jakob disease caused by a prion—a protein that does not require DNA or RNA to replicate and produce infection.
72. Herpes simplex, the most common sporadic encephalitis, often produces focal neurologic damage and must be aggressively treated with acyclovir.
73. Patients with acquired immunodeficiency syndrome (AIDS) may develop problems from the virus itself, the drugs used to treat it, or opportunistic infections.
74. Most patients with a headache due to a serious underlying illness have an abnormal physical examination. The sudden onset of “the worst headache of my life” should raise concern about an intracranial hemorrhage.
75. The use of narcotic analgesics for treatment of headaches should be strongly discouraged. 79. The first-choice drugs for acute migraine therapy are the triptans.
76. The best treatment for tension headache is usually amitriptyline.
77. Temporal arteritis should be considered in any elderly patient with new headaches.
78. The normal adult electroencephalogram (EEG), relaxed with eyes closed, is characterized by 9 to 11 cycles/sec activity in the back of the brain (occipital lobes) and is called the alpha rhythm.
79. Each different stage of sleep has a highly characteristic EEG pattern.
80. In most jurisdictions, a patient is considered to have died if he meets the criteria for brain death, even if his vital signs (e.g., pulse, blood pressure) are otherwise normal.
81. Strokes can be thrombotic, embolic, lacunar, or Hemorrhagic.
82. The clinical features, aetiology, and treatment of strokes are different depending on whether they involve the anterior circulation (carotid arteries) or posterior circulation (vertebral basilar arteries).
83. The most important modifiable risk factors for stroke are hypertension, smoking, heart disease, hyper lipidemia, and hyper homo=cysteinemia. Other modifiable risk factors include diabetes, alcohol consumption, drugs of abuse, oral contraceptives, and obesity.
84. When administered properly, tissue plasminogen activator (tPA) is a beneficial therapy for acute ischemic stroke.
85. The role of anticoagulation in cerebrovascular disease is the prevention of stroke in patients at high risk for cardiac emboli.
86. The best way to prevent strokes is to control the risk factors.
87. Surgery is superior to medical therapy in symptomatic stroke patients with a 70% stenosis or more in their internal carotid arteries.
88. The most important complications of subarachnoid hemorrhage are rebleeding, vasospastic ischemia, hydrocephalus, seizures, and syndrome of inappropriate antidiuretic hormone secretion (SIADH).
89. Accurate seizure classification guides appropriate antiepileptic therapy. Each type of seizures requires its own specific anticonvulsant drug.
90. All partial seizures should be evaluated with an MRI scan.
91. A significant change in antiepileptic drug levels should alert you to either noncompliance or a new drug interaction. Noncompliance is probably the most common cause of status epilepticus.
92. The most common cause of antiepileptic drug treatment failure is drug side effects.
93. Patients whose seizures are refractory to two appropriate antiepileptic drugs should be evaluated at an epilepsy center for definitive diagnosis and surgical evaluation.
94. The most common cause of aphasia in adults is stroke.
95. Broca’s aphasia is impaired comprehension, repetition, naming, and speech output due to a left frontal lobe lesion; Wernicke’s aphasia is fluent speech full of nonsense words and phrases due to a left temporal lobe lesion.