Dementia

Onset . . ■ Common causes Reversible Attention Arousallew)

Acute and dramatic. Illness, toxin, withdrawal Usually . Poor

Fluctuates

Chronic and insidious

Alzheimer's, multiinfarct dementia. HIV/AIDS Usually not Usually unaffected Normal ii rjviimiri"r>i iijiyriiiiniiiim irifiritin'niiiin iih.i n eyi m 'irniiiiiiiiiii^nnihicntfibiiwirm

Important points:

1. Both delirium and dementia may have hallucinations, illusions, delusions, memory im pairment (usually global in delirium, whereas remote memory is spared in early dementia), orientation difficulties (time, place, person), and "simdowiring" (worsened delirium or dementia at night),

2. In the elderly watch for pseudodementia, which is caused by depression and reversible with treatment.

3. Treatable causes of dementia include vitamin B, 7 deficiency, endocrine disorders (espe cially thyroid and parathyroid), uremia, syphilis, brain tumors, and normal-pressure hydrocephalus. Treatment of Parkinson s syndrome also may reverse dementia.

4. Watch for thiamine deficiency in alcoholics as the cause of delirium (Wernicke's encephalopathy, which classically presents with ataxia, ophthalmoplegia, nystagmus, and confusion). If untreated, it may progress to Korsakoff's syndrome (memory loss with confabulation; usually irreversible). Give thiamine before glucose in an alcoholic to prevent precipitating Wernicke's encephalopathy.

Causes of headache:

1. Tension headaches: most common cause. Look for long history of headaches and stress plus a feeling of tightness or stiffness, usually frontal or occipital and bilateral. Treat with stress reduction and acetaminophen or NSAID.

2. Cluster headaches: unilateral, severe, tender; occur in clusters. Oxygen may abort an attack

3. Migraine headache: look for aura, photophobia, nausea and vomiting, and positive family history. Patients may have neurologic symptoms during attacks, which usually begin between ages 10 and 30.Treat and prophylax with antimigraine medication (e.g., sumatriptan).

4. Tumor or mass: look for progressive neurologic symptoms, papilledema, intracranial hypertension (classically with nausea and vomiting, which may be projectile), mental status changes, and headache every day (classically worse in the morning). CT/MR1 should be ordered.

5. Pseudotumor cerebri: may mimic tumor or mass; both cause intracranial hypertension, papilledema, and daily headaches that classically are worse in the morning and may be accompanied by nausea and vomiting. Found in young obese females, who are unlikely to have a brain tumor; CT and MRJ. are negative. Pseudotumor cerebri may cause permanent vision loss. Treatment is usually supporti ve; weight loss usually helps. Large doses of vitamin A, tetracyclines, and withdrawal from corticosteroids are possible causes.

6. Meningitis: look for fever, Brudzinski's or Kernig's sign, cerebrospinal fluid findings (see above),

1. Subarachnoid hemorrhage: "worst headache" of patient s life; may be due to congenital berry aneurysm, rupture, or trauma. Look for grossly bloody cerebrospinal fluid. Treat supportively.

8. Extracranial causes: eye pain (optic neuritis, eyestrain from refractive errors, iritis, glaucoma), middle ear pain (otitis media, mastoiditis), sinus pain (sinusitis), oral cavity pain (toothache), herpes zoster with cranial nerve involvement, and nonspecific (malaise from any illness).

Cranial nerve (CN) lesions:

1. Olfactory (C,N 1): rarely important clinically. Kallmann's syndrome is anosmia plus hypogonadism due to deficiency of gonadolropin-reieasmg hormone.

2. Optic (C,N 2): you must be able to localize the lesion through the resultant visual deficit (e.g., bitemporal hemianopia due to a lesion at the optic chiasm), as on Step 1 boards. Most commonly tested are bitemporal hemianopia and monocular loss of vision (see ophthalmology chapter).

3. Oculomotor (CN 3): the cause may be benign (hypertension, diabetes mellitus) or serious (aneurysm, tumor, uncal herniation). With benign causes the pupil is spared (normal), and no treatment is needed. With serious causes the pupil is dilated and nonreactive ("blown"). Urgent diagnosis and. treatment, are required.

4. Trochlear (CN 4) and abducens (CN 6): see ophthalmology chapter.

5. Trigeminal (CN 5): innervates muscles of mastication and facial sensation (including the afferent limb of the corneal reflex). Patients may have trigeminal neuralgia (tic douloureux), which is characterized by unilateral shooting pains in the face in older adults and often triggered by activity (e.g., brushing teeth). Treat with, carbamazepine and anti-epilepsy medications. If the patient is young and/or female and/or the disease is bilateral, consider multiple sclerosis. Make sure to rule out other causes, such as tumor or stroke.

6. Facial (CN 7): innervates muscles of facial expression, taste in anterior two-thirds of tongue, skin of external ear, lacrimal and salivary glands (except parotid, gland), and stapedius muscle. Differentiate between upper motor neuron lesions (the forehead is spared on the affected side, and the cause is usually stroke or tumor) and lower motor neuron lesions (the forehead is involved on the affected side, and the cause is usually Bell's palsy or tumor) of the facial nerve. Patients may be unable to close the eye; give artificial tears to prevent corneal ulceration. Patients with Bell's palsy may get hyperaeusis due to stapedial muscle paralysis. If CNs 7 and. 8 are affected, think of possible cerebellopontine angle tumor (e.g., acoustic neuroma, especially in neurofibromatosis).

1. Vestibulocochlear (CN 8): for hearing and balance. Lesions cause deafness, tinnitus, and vertigo. In children, think of meningitis as a cause. In adults, think of toxins and medications (aspirin, aminoglycosides, loop diuretics, cisplatin), tumors (with CN 7 coinvolve-ment, think of acoustic neuroma), or stroke.

8. Glossopharyngeal (CN 9): innervates pharyngeal muscles and mucous membranes (afferent limb of gag reflex), parotid gland, taste in posterior third of tongue, skin of external tar, and carotid body and sinus. Look for loss of gag reflex and loss of taste in posterior third of tongue.

9. Vagus (CN 10): innervates muscles of palate, pharynx, larynx (efferent limb of gag reflex), taste buds in base of tongue, abdominal viscera, and skin of external ear, Look for hoarseness, dysphagia, and loss of gag or cough reflex. Think of aortic aneurysms or tumors, especially Pancoast lung tumors.

10. Spinal accessory (CN 11): innervates sternocleidomastoid and trapezius muscles. With a CN 1 ! lesion, the patient has trouble turning the head to the opposite side of lesion and shoulder droop.

11. Hypoglossal (CN 12): innervates muscles of the tongue. With a CN 12 lesion, a protruded tongue deviates to the side of the lesion.

Vitamin deficiencies may present with neurologic signs and symptoms:

1. Vitamin Bj dementia, peripheral neuropathy, loss of vibration sense in lower extremities, loss of position sense, ataxia, spasticity, hyperactive reflexes, and positive Babinskt's sign

2. Thiamine: peripheral neuropathy, contusion, ophthalmoplegia, nystagmus, ataxia, confusion, delirium, dementia

3. Vitamin E: loss of proprioception/vibratory sensation, areflexia, ataxia, and gaze palsy

4. Vitamin A: vision loss

5. Vitamin B6: peripheral sensory neuropathy (watch for isoniazid as a cause and give prophylactic B6 to patients taking isoniazid if given the choice)

Five main types of seizures are tested on boards (although there are others):

1. Simple partial (local, focal) seizures: may be motor (e.g., Jacksonian march), sensory (e.g., hallucinations), or psychic (cognitive or affective symptoms).The key point is that consciousness is not impaired.Treat with phenytoin, carbamazepine, or valproate.

2. Complex partial (psychomotor) seizures: any simple partial seizure followed by impairment of consciousness. Patients perform purposeless movements and may become aggressive if restraint is attempted (people who get in figh ts or kill people are not having a seizure!).The first-line agent is carbamazepine; phenytoin and valproate also are effective.

3. Absence (petit mal) seizures: never begin after the age of 20.They are brief (10-30-seco.nd duration), generalized seizures in which the main manifestation is loss of consciousness, often with eye or muscle ilutterings.The classic description is a child in a classroom who stares off into space in the middle of a sentence (the child is not daydreaming but having a seizure), then 20 seconds later resumes the sentence.There is no postictal state (an important differential point).The first-line agent is ethosuximide; valproate also is effective.

4. Tonic clonic (grand mal) seizures: the classic seizures that may have an aura; tonic muscle contraction is followed by clonic contractions, usually lasting 2-5 minutes. Patients often have incontinence and a postictal state (drowsiness, confusion, headache, muscle soreness). Treat with phenytoin, carbamazepine, or valproate.

5. Febrile seizures: between the ages of 6 months and .5 years old, children may have a seizure due to fever. The seizure is usually of the tonic-donic, generalized type, and no specific seizure treatment is required. Treat the underlying cause of the fever, if possible, and give acetaminophen. Such children do not have epilepsy, and the chances of their get ting it are just barely higher than in the general population. Make sure that affected children, do not have meningitis, tumor, or other serious cause of seizure. The board, question will give clues in the case description if you are expected to pursue work-up for a serious condition.

Secondary seizure disorder may be caused by:

» Mass (tumor, hemorrhage)

« Metabolic disorder (hypoglycemia, hypoxia, phenylketonuria, hyponatremia)

■ Toxins (lead, cocaine, carbon monoxide)

■ Drug withdrawal (alcohol, barbiturates, benzodiazepines, too-rapid anticonvulsant withdrawal)

e Cerebral edema (severe or malignant hypertension; also watch for pheocltromocytoina)

» Eclampsia

■ Central nervous system infections (meningitis, encephalitis, toxoplasmosis, cysticercosis) a Trauma » Stroke

Cysticercosis is due to infection with the larval form of Taenia solium, the pork tapeworm, and .most often is seen in patients with AIDS and immigrants. On CT scan the lesion often is described as "ring-enhancing." Treat with niclosamide or praziquantel. In secondary seizures of any etiology, treat the underlying disorder and use diazepam, or pbenytoin acutely to control seizure.

Note: For all seizures, secure the airway and, if possible, roll the patient onto his or her side to prevent aspiration.

Status epilepticus: when seizures of any type follow one after the other with no intervening periods of consciousness. May occur spontaneously or result from too-rapid withdrawal of anticonvulsants. Treat with IV diazepam, lorazepam, or phenytoin. Remember to protect the airway and intubate if necessary.

Important points:

1. Hypertension may cause seizures or convulsions, headache, and confusion, stupor, or menial status changes.

2. All anticonvulsants are teratogenic, and women need counseling about the risks of preg nancy. Do a pregnancy test before starting an anticonvulsant.

Cerebrovascular disease (stroke, cerebrovascular accident): the most common cause of neurologic disabili ty in the U.S. and the third leading cause of death. Ischemia from atherosclerosis is by far the most common cause; other classic causes include, atrial fibrillation with resultant clot formation and emboli to the brain and septic emboli from endocarditis. Treatment for acute stroke in evolution is supportive (e.g., airway, oxygen, IV fluids). Heparin is controversial and should be avoided if the patient is hypertensive; it should not be gi ven until a hemorrhagic stroke has been ruled out by CT.The vascular surgery chapter discusses the role of carotid endarterec-tomy, which is not done emergently.

Transient, ischemic attack (TIA): focal neurologic deficit that lasts minutes to hours, then resolves spontaneously; often a precursor to stroke. The classic presentation is ipsilateral blindness (amaurosis fug ax) and/or unilateral hemiplegia, hemiparesis, weakness, or clumsiness, (let a carotid duplex scan to look for stenosis. Heparin may be given acutely (if not contraindi-cated), but for long-term therapy use aspirin-antiplatelet medications, or carotid endartercc-tomy (if carotid stenosis > 70%).

Huntington's disease: autosomal dominant condition that usually begins at 35-50 years of age. Look for choreiform movements (irregular, spasmodic, involuntary movements of the limbs or facial muscles) and progressive intellectual deterioration, dementia, and psychiatric disturbances. Atrophy of the caudate nucleus may be seen on CT/MRi.Treatment is supportive; antipsychotics may help.

Parkinson's disease: classic tetrad of slowness or poverty of movement, muscular rigidity ("lead pipe" and "cog--wheel"), resting "pill-rolling" tremor (which disappears with movement and sleep), and postural instability (shuffling gait and festination). Patients also may have dementia and depression. The mean age of onset; is around 60. The cause is loss of dopaminergic neurons, especially in the substantia nigra, which projects to the basal ganglia; the result is decreased dopamine in the basal ganglia. Drug therapy aims to increase dopamine. Options include levodopa/carbi-dopa, bromoeriptine/pergolide, monoamine oxidase-B inhibitors (selegiline), amantadine, anticholinergics (trihexyphenidyl, benztropine), and antihistamines (diphenhydramine).

Note: Antipsychotics may cause Parkinson-like symptoms in schizophrenics. Treat with anticholinergics (benztropine, trihexyphenidyl) or antihistamines (diphenhydramine).

Tremor and chorea: resting tremor generally due to basal ganglia disease (chorea), intention tremor due to cerebellar disease, and hemibailisinus (random, violent, unilateral flailing of the limbs) due to a lesion in the subthalamic nucleus. Besides Parkinson's disease, a resting tremor may be due to hyperthyroidism, anxiety, drug withdrawal or intoxication, or a benign (essential) hereditary tremor (usually autosomal dominant; look for a positive family history, and use beta blockers to reduce the tremor). Watch for Wilson's disease (hepatolenticular degeneration) and asterixis (outstretched hands flap slowly and involuntarily) in patients with liver and kidney failure.

Cerebellar disorders: in children, think of brain tumor (cerebellar astrocytoma, medulloblas tomas), hydrocephalus (enlarging head in infants younger than 6 months, Arnold- Chiari and Dandy-Walker syndromes), Friedreich's ataxia (autosomal recessive), or ataxia-telangiectasia (the diagnosis is in the name). Friedreich's ataxia starts between S and IS years of age and presents with areflexia, loss of vibration or position sense, and cardiomyopathy. In adults, think of alcoholism, tumor, ischemia or hemorrhage, or multiple sclerosis.

Amyotrophic lateral sclerosis (Lou Gehrig's disease): an idiopathic degeneration of both upper and lower motor neurons that is more common in males.The mean age at onset is 55.The key is to notice a combination of* upper menor neuron lesion signs (spasticity, hyperreflexia, positive Babinski's sign) and lower motor neuron lesion signs (fasciculations, atrophy, flacc.idi.ty) in the same patient. Treatment is supportive, but 50% of patients die within 3 years of onset.

"Floppy baby"syndrome (infants with hypotonia or flaccidity) may Ik- caused by two disorders:

1. Wordnig Hoffmann disease: autosomal recessive degeneration of anterior horn cells in the spinal cord and brainstem (lower motor neurons). Most infants are hypotonic at birth, and all are affected by 6 months. Look for a positive family history, long and slowly progressive course of di sease. Treatment is supportive.

2. Infant botulism: look for sudden onset and a history of honey ingestion (or other home-canned foods). Diagnosis is made by finding Clostridium Botulinum toxin or organisms in the feces. Treat on an inpatient basis with close monitoring of respiratory status. Patients may need intubation for respiratory muscle paralysis. Spontaneous recovery usually occurs within 1 week.

Peripheral neuropathies have multiple causes:

1. Metabolic: diabetes nielli tus (autonomic and sensory neuropathy), uremia, hypothyroidism

2. Nutritional: deficiencies of vitamin B1? , B6 (look for history of isoniazid), thiamine (dry beriberi), or vitamin E

3. Toxins and medications: lead (classic symptom is wristdrop or footdrop; look for coexist ing central nervous system or abdominal symptoms) or other heavy metals, isoniazid, vincristine, eth.anibut.o.1 (especially optic neuritis), aminoglycosides (especially CN 8)

Postinfection/immuni/ation and autoimmune: Guillain Barre syndrome, systemic; lupus erythematosus, polyarteritis nodosa, scleroderma, sarcoidosis, amyloidosis

5. Trauma: carpal tunnel syndrome (median nerve entrapment; at the wrist), pressure paral ysis (radial nerve palsy in alcoholics), or fractures. Carpal tunnel syndrome usually is due to repet itive physical acti vity but may be a presentation of acromegaly or hypothyroidism. Look for positive Tine! and Phalen signs.

6. Infectious: Lyme disease, diphtheria, 111V, tick bite, leprosy

Note: Nerve conduction velocity is slowed with a peripheral neuropathy.

Myasthenia gravis (MG): autoimmune disease that destroys acetylcholine receptors. MG usually presents in women aged 20-40, Look for ptosis, diplopia, and general muscle fatigability, especially toward the end of the day. Diagnosis is made with the Tensilon test. Injection of edrophonium (trade name: Tensilon), a short-acting anticholinesterase, improves muscle weakness. Watch for associated thymomas; most patients with MG improve after removal of the thymus, which is considered part of standard treatment. Most patients have antibodies to acetylcholine receptors in their serum. Treat with long-acting anticholinesterase (pyridostigmine, neostigmine).

Eaton-Lambert syndrome: a paraneoplastic syndrome (classically seen with small cell lung cancer) characterized by muscle weakness, with sparing of the extraocular muscles (MG almost always has prominent involvement, of extraocular muscles). Eaton-Lambert syndrome lias a different mechanism of disease (impaired release of acetylcholine from nerves) and a differential response to repetitive nerve stimulation (MG worsens, Eaton-Lambert improves).

Important points:

1. Do not forget organophosphate poisoning as a cause for niyasthenic-like muscle weakness. Usually it occurs with agricultural exposure. Symptoms of parasympathetic excess also are present (e.g., miosis, excessive bronchial secretions, urinary urgency, diarrhea). Edrophonium causes worsening of the muscular weakness. Treatment is atropine and pralidoxiine.

2. Aminoglycosides in high doses may cause myasthenic-like muscular weakness and prolong the effects of muscular blockade in anesthesia.

Muscular dystrophy: most commonly due to Ducheime muscular dystrophy, an X-linked recessive disorder of dystrophin that usually presents in boys aged 3-7. l.ook for muscle weakness, markedly elevated creatine kinase, and pseudohypertrophy of the calves (due to fatty and fibrous infiltration of the degenerating muscle). 1Q often is less than normal. Gowers' sign is classic (when the patient tries to rise from a prone position, he "walks" the hands and feet toward each other). Muscle biopsy establishes the diagnosis. Treatment is supportive; most patients die by age 20. Other muscular dystrophies:

1. Becker muscular dystrophy: also an X-linked recessive dystrophin disorder, but milder i. Facioscapulohumeral dystrophy: autosomal dominant disease that affects the areas in the name (face, shoulder girdle) and begins between ages 7 and 20. Life expectancy is normal.

3. Limb-girdle dystrophy: affects pelvic and shoulder muscles; begins in adulthood.

4. Mitochondrial myopathies: interesting because they are inherited mitochondrial defects (passed only from mother to offspring; males cannot transmit). The key phrase is "ragged red fibers" on biopsy specimen. Ophthalmoplegia usually is present.

5. Myotonic dystrophy: autosomal dominant disorder that presents between 2.0 and 30 years of age. Myotonia (inability to relax muscles ) classically presents as inability to relax the grip (inability to release a handshake). Look for coexisting mental retardation, baldness, and testicular/ovarian atrophy. Treatment is supportive and. includes genetic counseling. Diagnosis is clinical.

Note; Do not forget the rare glycogen storage diseases (autosomal recessive) as a cause for muscular weakness (especially McArdlc's disease, a deficiency in glycogen phosphorylase that is relatively mild and presents with weakness and cramping after exercise).

CHAPTER J ^

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