(17) Nervous System Reds Flashcards
cherry red color suggests ?
carbon monoxide poisoning
Diabetic patients with small-fiber
neuropathy report
whereas those with large-fiber neuropathy experience
sharp, burning, or shooting foot pain
numbness and tingling or even
no sensation at all.
Primary headaches include
secondary headaches arise from
migraine, tension, cluster, and trigeminal autonomic cephalagias
underlying structural, systemic, or infectious causes and may be life threatening
Subarachnoid hemorrhage classically
presents as
Severe headache and stiff neck accompany
Dull headache increased by coughing and sneezing, especially when recurring in the same location, occurs in
“the worst headache of my
life” with instantaneous onset
meningitis
mass lesions from brain tumors or abscess
Migraine headache is often preceded by
an aura or prodrome, and is highly likely
if three of the five “POUND” features are
present: Pulsatile or throbbing; Oneday
duration, or lasts 4 to 72 hours if
untreated; Unilateral; Nausea or vomiting;
Disabling or intensity causing interruption
of daily activity
a
Feeling light-headed, weak in the legs, or about to faint points to presyncope from vasovagal stimulation, orthostatic hypotension, arrhythmia, or side effects from blood pressure and other medications
a
Vertigo often reflects vestibular disease,
usually from peripheral causes
in the inner ear such as benign positional
vertigo, labyrinthitis, or Ménière
disease
a
Ataxia, diplopia, and dysarthria are suspicious for vertebrobasilar TIA or stroke.25–30 Also consider posterior fossa tumor and migraine with brainstem aura.
a
Abrupt onset of motor and sensory deficits occurs in TIA and stroke.25–30 Progressive subacute onset of lower extremity weakness suggests Guillain–Barré syndrome.31 Chronic, more gradual, onset of lower extremity weakness occurs in primary and metastatic spinal cord tumors
a
Focal or asymmetric weakness has both central (ischemic, thrombotic, or mass lesions) and peripheral causes ranging from nerve injury to the neuromuscular junction disorders to myopathies
a
Proximal limb weakness, when symmetric with intact sensation, occurs in myopathies from alcohol, drugs like glucocorticoids, and inflammatory muscle disorders like polymyositis and dermatomyositis. In the neuromuscular junction disorder myasthenia gravis, there is proximal typically asymmetric weakness that gets worse with effort (fatigability), often with associated bulbar symptoms such as diplopia, ptosis, dysarthria, and dysphagia
a
Bilateral predominantly distal weakness,
often with sensory loss, suggests
a polyneuropathy, as in diabetes.
a
Sensory changes can arise at several levels: local nerve compression or “entrapment,” seen in hand numbness in distributions specific to the median, ulnar, or radial nerve; nerve root compression with dermatomal sensory loss from vertebral bone spurs or herniated discs; or central lesions from stroke or multiple sclerosis.
a
Burning pain occurs in painful sensory
neuropathies from conditions like
diabetes
a
A pattern of stocking, then glove, sensory
loss occurs in polyneuropathies,
especially from diabetes; multiple
patchy areas of sensory loss in different
limbs suggest mononeuritis multiplex,
seen in diabetes and rheumatoid
arthritis
a
Causes include seizures, “neurocardiogenic”
conditions such as vasovagal
syncope, postural tachycardia syndrome,
carotid sinus syncope, and
orthostatic hypotension, and cardiac
disease causing arrhythmias, especially
ventricular tachycardia and
bradyarrhythmias.37 Stroke or subarachnoid
hemorrhage are unlikely
causes of syncope unless both hemispheres
are affected
a
In vasovagal syncope, the most common cause of syncope, look for the prodrome of nausea, diaphoresis, and pallor triggered by a fearful or unpleasant event, then vagally mediated hypotension, often with slow onset and offset. In syncope from arrhythmias, onset and offset are often sudden, reflecting loss and recovery of cerebral perfusion
a
Common causes of acute symptomatic seizures include: head trauma; alcohol, cocaine, and other drugs; withdrawal from alcohol, benzodiazepines, and barbiturates; metabolic insults from low or high glucose or low calcium or sodium; acute stroke; and meningitis or encephalitis
a
Tonic–clonic motor activity, bladder or bowel incontinence, and postictal state characterize generalized seizures. Unlike syncope, tongue biting or bruising of limbs may occur
a
Epilepsy is more common in infants and
older adults. The baseline neurologic
examination is frequently normal
a
Generalized epilepsy syndromes usually
begin in childhood or adolescence;
adult-onset seizures are
usually partial
a
Low-frequency unilateral resting tremor, rigidity, and bradykinesia typify Parkinson disease.43,44 Essential tremors are high-frequency, bilateral, upper extremity tremors that occur with both limb movement and sustained posture and subside when the limb is relaxed; head, voice, and leg tremor may also be present
a
Reversible causes of restless legs
syndrome include pregnancy, renal
disease, and iron deficiency
a
The AHA/ASA report cites the wellvalidated ABCD2 scoring system for predicting ischemic stroke within 2, 7, and 90 days after TIA: Age ≥60 years, initial Blood pressure ≥140/90 mm Hg, Clinical features of focal weakness or impaired speech without focal weakness, Duration 10 to 59 minutes or ≥60 minutes, and Diabetes
a
Cardiovascular causes of death, including stroke, are the greatest contributors to the 5-year disparity in life expectancy for African American men compared to white men and the 4-year racial disparity for women.49 However, the racial gap in life expectancy has recently been declining
a
History and careful neurologic examination to assess level of consciousness and focal findings are essential for diagnosing stroke, followed by neuroimaging to distinguish ischemic from hemorrhagic stroke
a
Stroke subtypes include: TIA; ischemic— cardioembolic, large artery atherosclerotic, lacunar, or cryptogenic; hemorrhagic—intracerebral, subarachnoid; and other—dural sinus venous thrombosis, carotid and vertebral artery dissection, or asymptomatic aneurysm
a
The Mini-Mental State Examination,
which takes 7 to 10 minutes to administer,
is the best studied, and at a score
cutpoint of 23 to 24, has a median
likelihood ratio (LR) of 6.3 for a positive
test and 0.19 for a negative test
a
Loss of smell occurs in sinus conditions,
head trauma, smoking, aging,
use of cocaine, and Parkinson disease
a
Inspect each disc carefully for bulging
and blurred margins (papilledema);
pallor (optic atrophy); and cup
enlargement (glaucoma
a
Look for prechiasmal, or anterior, defects seen in glaucoma, retinal emboli, optic neuritis (visual acuity poor); bitemporal hemianopsias from defects at the optic chiasm, usually from pituitary tumor; and homonymous hemianopsias or quadrantanopsias in postchiasmal lesions, usually in the occipital or parietal lobe, with associated findings of stroke (visual acuity normal).84
a
If the large pupil reacts poorly to light or anisocoria worsens in light, the large pupil has abnormal pupillary constriction, seen in CN III palsy. If ptosis and ophthalmoplegia are also present, consider intracranial aneurysm if the patient is awake, and transtentorial herniation if the patient is comatose.
a
If both pupils react to light and anisocoria worsens in darkness, the small pupil has abnormal pupillary dilation, seen in Horner syndrome and simple anisocoria
a
Monocular diplopia is seen in local problems with glasses or contact lenses, cataracts, astigmatism, or ptosis. Binocular diplopia occurs in CN III, IV, and VI neuropathy (40% of patients), and eye muscle disorders from myasthenia gravis, trauma, thyroid ophthalmopathy, and internuclear ophthalmoplegia.86
a
Nystagmus is seen in cerebellar disease, especially with gait ataxia and dysarthria (increases with retinal fixation), and vestibular disorders (decreases with retinal fixation); and in internuclear ophthalmoplegia
a
Ptosis is seen in 3rd nerve palsy (CN III),
Horner syndrome (ptosis, miosis,
forehead anhidrosis), or myasthenia
gravis.
a
Difficulty clenching the jaw or moving it to the opposite side suggests masseter and lateral pterygoid weakness, respectively. Jaw deviation during opening points to weakness on the deviating side
a
Look for unilateral weakness:
bilateral weakness in:
(neuro)
CN V pontine lesions
bilateral hemispheric disease
CNS patterns from stroke include ipsilateral
facial and body sensory loss
from contralateral cortical or thalamic
lesions; ipsilateral face, but contralateral
body sensory loss in brainstem
lesions.
a
Isolated sensory loss occurs in peripheral
nerve disorders, including lesions
of the trigeminal nerve (CN V).
a
Blinking is absent in both eyes in
Absent blinking and sensorineural hearing loss occur in
CN V lesions and on the side of weakness in lesions of CN VII
acoustic neuroma
Flattening of the nasolabial fold and
drooping of the lower eyelid suggest
facial weakness
A peripheral injury to CN VII, as seen in Bell palsy, affects both the upper and lower face; a central lesion affects mainly the lower face. Loss of taste, hyperacusis, and increased or decreased tearing also occur in Bell palsy.8
a
In unilateral facial paralysis, the
mouth droops on the paralyzed side
when the patient smiles or grimaces.
a
The whispered voice test is both sensitive
(>90%) and specific (>80%)
when assessing presence or absence
of hearing loss
a
Excess cerumen, otosclerosis, and otitis
media cause conductive hearing
loss; presbyacusis from aging is usually
from sensorineural hearing loss
a
Vertigo with hearing loss and nystagmus
typifies Ménière disease
a
Hoarseness occurs in vocal cord
paralysis; nasal voice in paralysis of
the palate
a
Difficulty swallowing suggests pharyngeal
or palatal weakness.
a
The palate fails to rise with a bilateral
lesion of CN X. In unilateral paralysis,
one side of the palate fails to rise and,
together with the uvula, is pulled
toward the normal side
a
Unilateral absence of this reflex suggests
a lesion of CN IX, and perhaps
CN X
a
Trapezius weakness with atrophy and fasciculations points to a peripheral nerve disorder. In trapezius muscle paralysis, the shoulder droops, and the scapula is displaced downward and laterally
a
A supine patient with bilateral weakness
of the SCM muscles has difficulty
raising the head off the pillow
a
Tongue atrophy and fasciculations
are present in amyotrophic
lateral sclerosis and past polio
a
In a unilateral cortical lesion, the protruded
tongue deviates away from
the side of the cortical lesion. In CN XII
lesions, the tongue deviates to the
weak side.
a
Abnormal positions alert you to conditions
such as mono- or hemiparesis
from stroke
a
Atrophy results from PNS disorders such as diabetic neuropathy and diseases of the muscles themselves. Hypertrophy is an increase in bulk with normal or increased strength; increased bulk with diminished strength is called pseudohypertrophy, seen in the Duchenne form of muscular dystrophy. Corticospinal tract injury can cause mild atrophy due to decreased muscle use
a
Furrowing between the metacarpals, and flattening of the thenar and hypothenar eminences (also seen in median and ulnar nerve damage respectively), suggest atrophy
a
Other causes of muscular atrophy include motor neuron diseases, diseases affecting the peripheral motor system projecting from the spinal cord, and protein–calorie malnutrition
a
Fasciculations with atrophy and muscle
weakness suggest peripheral motor
neuron disease.
a
Decreased resistance suggests disease
of the PNS or cerebellum, or the
acute stages of spinal cord injury.
a
Marked floppiness indicates
muscle hypotonia or flaccidity, usually from a peripheral motor system disorder
Spasticity is velocity-dependent increased tone that worsens at the extremes of range. Spasticity, seen in central corticospinal tract diseases, is rate-dependent, increasing with rapid movement. Rigidity is increased resistance throughout the range of movement and in both directions; it is not rate-dependent
a
Impaired strength or weakness is called paresis. Absent strength is paralysis, or plegia. Hemiparesis refers to weakness of one half of the body; hemiplegia refers to paralysis of one half of the body. Paraplegia means paralysis of the legs; quadriplegia means paralysis of all four limbs
a
Extensor weakness is seen in peripheral
radial nerve damage, and in the
hemiplegia of CNS disease seen in
stroke or multiple sclerosis
a
A weak grip is seen in cervical radiculopathy, median or ulnar peripheral nerve disease, and pain from de Quervain tenosynovitis, carpal tunnel syndrome, arthritis, and epicondylitis
a
Weak finger abduction occurs in ulnar
nerve disorders.
a
Inspect for weak opposition of the
thumb in median nerve disorders
such as carpal tunnel syndrome
a
Symmetric weakness of the proximal muscles suggests myopathy; symmetric weakness of distal muscles suggests polyneuropathy, or disorders of peripheral nerves.
a
In cerebellar disease, look for nystagmus,
dysarthria, hypotonia, and ataxia
a
In cerebellar disease, instead of alternating quickly, these movements are slow, irregular, and clumsy, an abnormality called dysdiadochokinesis. Upper motor neuron weakness and basal ganglia disease can also impair these movements, but not in the same manner.
a
Dysdiadochokinesis points to ?
cerebellar disease
In cerebellar disease, movements are clumsy, unsteady, and inappropriately variable in their speed, force, and direction. In dysmetria the patient’s finger may initially overshoot the mark, but then reach it fairly well. An intention tremor may appear toward the end of the movement
a
In cerebellar disease, incoordination modestly worsens with eyes closed, indicating loss of position sense. Consistent deviation to one side which worsens with the eyes closed, referred to as past pointing, suggests cerebellar or vestibular disease
a
In cerebellar disease, the heel may overshoot the knee, then oscillate from side to side down the shin. If position sense is absent, the heel lifts too high and the patient tries to look. With eyes closed, performance is poor.
a
Gait abnormalities increase risk of
falls.
a
A uncoordinated gait with reeling and
instability is ataxic. Ataxia is seen in cerebellar
disease, loss of position sense,
and intoxication
a
Tandem walking may reveal ataxia
that is not otherwise obvious.
a
Walking on toes and heels may reveal
distal leg weakness. Inability to heelwalk
is a sensitive test for corticospinal
tract damage
a
Difficulty hopping points to
weakness, lack of position sense,
or cerebellar dysfunction
a
Difficulty doing shallow knee bends
suggests
proximal weakness
(extensors of the hip)
weakness of the quadriceps
(extensor of the knee)
or both
Proximal muscle weakness in the pelvic
girdle and legs causes difficulty
with both of these activities.
a
In ataxia from dorsal column disease and loss of position sense, vision compensates for the sensory loss. The patient stands fairly well with eyes open but loses balance when they are closed, a positive Romberg sign. In cerebellar ataxia, the patient has difficulty standing with feet together whether the eyes are open or closed
a
Pronator drift occurs when one forearm and palm turn inward and down (Fig. 17-36) and is both sensitive and specific for a corticospinal tract lesion in the contralateral hemisphere. Downward drift of the arm with flexion of fingers and elbow is also seen.89
a
In loss of position sense the arms drift sideward or upward, sometimes with writhing movements of the hands; the patient may not recognize the displacement and when asked, corrects it poorly. In cerebellar incoordination, the arm returns to its original position but overshoots and bounces
a
Refer to specialty textbooks for discussion
of spinal cord syndromes with
crossed sensory findings, both ipsilateral
and contralateral to the spinal
cord injury
a
Meticulous sensory mapping helps establish the level of a spinal cord lesion and whether a more peripheral lesion is in a nerve root, a major peripheral nerve, or one of its branches
a
A hemisensory loss pattern suggests a lesion in the contralateral cerebral hemisphere; a sensory level (when one or more sensory modalities are reduced below a dermatome on one or both sides) suggests a spinal cord lesion
a
Symmetric distal sensory loss suggests
a diabetic polyneuropathy. You
may miss this finding unless you compare
distal and proximal sensation
a
Here, all sensation in the hand is lost. Repetitive testing in a proximal direction reveals a gradual return to normal sensation at the wrist. This pattern does not fit either peripheral nerve damage or dermatomal loss (see pp. 756–757). If bilateral, it suggests the “glove” of the “stockingglove” sensory loss of polyneuropathy, often seen in alcoholism and diabetes
a
Analgesia refers to absence of pain sensation, hypalgesia refers to decreased sensitivity to pain, and hyperalgesia refers to increased pain sensitivity
a
Anesthesia is absence of touch sensation,
hypesthesia is decreased sensitivity
to touch, and hyperesthesia is
increased sensitivity
a
Vibration sense is often the first sensation lost in a peripheral neuropathy and increases the likelihood of peripheral neuropathy 16-fold.8 Causes include diabetes, alcoholism, and posterior column disease, seen in tertiary syphilis or vitamin B12 deficiency
a
Testing vibration sense in the trunk is
useful when identifying the level of a
cord lesion
a
Loss of position sense, like loss of vibration sense, is seen in tabes dorsalis, multiple sclerosis, or B12 deficiency from posterior column disease, and in diabetic neuropathy
a
If touch and position sense are normal, decreased or absent discriminative sensation indicates a lesion in the sensory cortex. Stereognosis, number identification, and two-point discrimination are also impaired in posterior column disease
a
Astereognosis refers to the inability to
recognize objects placed in the hand
a
The inability to recognize numbers, or
graphanesthesia, indicates a lesion in
the sensory cortex
a
Lesions of the sensory cortex increase
the distance between two recognizable
points
a
Lesions of the sensory cortex impair
the ability to localize points accurately
a
With lesions of the sensory cortex,
only one stimulus may be recognized.
The stimulus to the side opposite the
damaged cortex is extinguished.
a
In spinal cord injury, the sensory level may be several segments lower than the spinal lesion, for reasons that are not well understood. Percussing for the level of vertebral pain may be helpful
a
Hyperactive reflexes (hyperreflexia) are seen in
CNS lesions of the descending corticospinal tract
- Look for associated upper motor neuron findings of weakness, spasticity, or a positive Babinski sign
Hypoactive or absent reflexes (hyporeflexia)
occur in lesions of the spinal
nerve roots, spinal nerves, plexuses,
or peripheral nerves. Look for associated
findings of lower motor unit disease,
namely weakness, atrophy, and
fasciculations
a
The slowed relaxation phase of
reflexes in hypothyroidism is often
best detected during the ankle reflex
a
Sustained clonus points to CNS disease. The ankle plantar flexes and dorsiflexes repetitively and rhythmically. Clonus must be present for a reflex to be graded
a
Abdominal reflexes may be absent in
both central and peripheral nerve
disorders
a
Dorsiflexion of the big toe is a positive
Babinski response (Fig. 17-61), arising
from a CNS lesion affecting the corticospinal
tract (sensitivity ∼50%; specificity
99%).96 The Babinski response
can be transiently positive in unconscious
states from drug or alcohol
intoxication and during the postictal
period following a seizure
a
A marked Babinski response is occasionally
accompanied by reflex flexion
at hip and knee
a
Loss of the anal reflex suggests a
lesion in the S2–3–4 reflex arc, seen
in cauda equina lesions
a
Inflammation in the subarachnoid space causes resistance to movement that stretches the spinal nerves (neck flexion), the femoral nerve (Brudzinski sign), and the sciatic nerve (Kernig sign).
a
Neck stiffness with resistance to flexion is found in ∼84% of patients with acute bacterial meningitis and 21% to 86% of patients with subarachnoid hemorrhage.97 It is most reliably present in severe meningeal inflammation but its overall diagnostic accuracy is low.
a
Flexion of both the hips and knees is a
positive Brudzinski sign
a
Pain and increased resistance to knee
extension are a positive Kernig sign
a
The mechanism of this sign is similar to the positive straight leg raise test. Irritation or compression of a lumbar or sacral nerve root or the sciatic nerve causes radicular or sciatic pain radiating into the leg when the nerve is stretched by extending the leg
a
The frequency of Brudzinski and Kernig signs in patients with meningitis has a reported range of 5% to 60%.97 Sensitivity and specificity for Brudzinski and Kernig signs are reported as ∼5% and 95% in limited study sets but are used in emerging scoring systems and merit more systematic investigation
A
Compression of the spinal nerve root as it passes through the vertebral foramen causes a painful radiculopathy with associated muscle weakness and dermatomal sensory loss, usually from a herniated disc. More than 95% of disc herniations occur at L4–L5 or L5–S1, where the spine angles sharply posterior. Look for confirming ipsilateral leg wasting or weak ankle dorsiflexion, which make the diagnosis of sciatica five times more likely
a
Pain radiating into the ipsilateral leg
is a positive straight leg test for lumbosacral
radiculopathy. Foot dorsiflexion
can further increase leg pain in lumbosacral
radiculopathy, sciatic neuropathy,
or both. Increased pain when the
contralateral healthy leg is raised is a
positive crossed straight-leg raise sign.
These maneuvers stretch the affected
nerve roots and sciatic nerve
a
Sensitivity and specificity of positive ipsilateral straight leg raise for lumbosacral radiculopathy in patients with sciatica are relatively low, with an LR of only 1.5. For the crossed straight-leg raise the LR is higher,
a
Sudden, brief, nonrhythmic flexion of
the hands and fingers followed by
recovery indicates asterixis, seen in
liver disease, uremia, and hypercapnia
a
In winging, the medial border of the scapula juts backward (Fig. 17-66), suspicious for weakness of the trapezius or serratus anterior muscle (seen in muscular dystrophy), or injury to the long thoracic nerve.
a
Determining prognosis after coma is complex and is complicated by use of therapeutic hypothermia. Research targets include clinical examination, EEG patterns, serum biomarkers, and imaging. Careful neurologic examination remains a mainstay of prognosis, especially after 72 hours
a
Structural lesions from stroke,
abscess, or tumor mass may lead to
asymmetrical pupils and loss of the
light reaction
a
In structural hemispheric lesions, the
eyes “look at the lesion” in the affected
hemisphere
a
In irritative lesions from epilepsy or a
unilateral pontine lesion, the eyes “look
away” from the affected hemisphere
a
In a comatose patient with absent doll’s eye movements, the ability to move both eyes to one side is lost, suspicious for a lesion of the midbrain or pons
a
No response to stimulation indicates
brainstem injury
a
Two stereotypic
responses predominate: decorticate
rigidity and decerebrate rigidity
a
No response on one side suggests a
corticospinal tract lesion
a
The hemiplegia of acute cerebral
infarction is usually flaccid at first. The
limp hand drops to form a right angle
with the wrist
a
A flaccid arm drops rapidly, like a rock
a
In acute hemiplegia, the flaccid leg
falls more rapidly
a
In acute hemiplegia, the weak leg falls
rapidly into extension, with external
rotation at the hip
a
Meningeal signs are suspicious for
meningitis or subarachnoid hemorrhage
a
Consider alcohol, liver failure, or uremia.
Note any jaundice, cyanosis, or the
cherry red color of carbon monoxide
poisoning.
Look for bruises, lacerations, or swelling.
Examine closely for hypertensive retinopathy
and papilledema, an important sign
of elevated intracranial pressure.
Corneal reflex loss occurs in coma and
lesions affecting CN V or CN VII.
Blood or cerebrospinal fluid in the nose
or the ears suggests a skull fracture; otitis
media suggests a possible brain abscess.
Tongue injury suggests a seizure.
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