Patients with dense neglect may fail to describe items on one side of a picture or of their surroundings, or may fail to bisect a line properly. Olfaction cranial nerve I is rarely tested, but when this is important, each nostril should be tested separately with a nonnoxious stimulus, such as coffee or vanilla. Funduscopic examination is the only means by which a part of the central nervous system the retina can be directly visualized. The presence of nystagmus should be noted.
Muscles of mastication V are tested by assessing strength of jaw opening and palpating over the masseters bilaterally while the jaw is clenched. Facial sensation can be tested to all modalities over the forehead V1 , cheek V2 , and jaw V3. The afferent limb of the corneal reflex is mediated by this nerve. Muscles of facial expression VII are tested by having patients raise their eyebrows, squeeze their eyes shut, or show their teeth.
Though uncommonly tested, taste over the anterior two-thirds of the tongue is mediated by this nerve and can be evaluated with sugar or another nonnoxious stimulus. Hearing VIII may be evaluated in each ear simply by whispering or rubbing fingers; more detailed assessment of hearing loss may be accomplished with the Weber or Rinne tuning fork Hz test.
Palatal elevation should be symmetric and the voice should not be hoarse or nasal IX and X. Failure of the right palate to elevate implies pathology of the right glossopharyngeal nerve. The gag reflex is also mediated by these nerves. Sternocleidomastoid strength is tested by having the patient turn the head against resistance; weakness on turning to the left implies a right accessory nerve XI problem.
The trapezius muscle is tested by having the patient shrug their shoulders. Tongue protrusion should be in the midline. If the tongue deviates toward the right, the problem lies with the right hypoglossal nerve XII.
The presence of fasciculations or of adventitious movements such as tremor or myoclonus should also be noted. Tone is one of the most important parts of the motor exam. Abnormalities of tone such as spasticity and rigidity are discussed in subsequent chapters. Tone in the lower extremities can be tested well only with the patient supine.
The examiner lifts the leg up suddenly under the knee; only in the presence of increased tone will the heel come off the bed. Finally, strength or power is assessed, by both functional observation and direct confrontation Fig. For each movement, the predominant muscle, peripheral nerve, and nerve root are given. Reproduced with permission from Ginsberg L. Lecture Notes: Neurology, 8th ed. Oxford: Blackwell Publishing, — The patient may be asked to rise from a chair without using the arms or to walk on the heels or toes.
Oxford: Blackwell Publishing, In the lower extremities, patellar knee jerk and ankle reflexes are the ones commonly tested. The adductor reflex can also be tested. The Babinski sign is sought by stroking the lateral sole of the foot while observing for extension of the great toe. Clonus, if present, can be elicited by forcibly dorsiflexing the ankle when it is relaxed. In the upper extremities, the biceps, brachioradialis, and triceps reflexes are the ones commonly tested.
Pectoral and finger flexor reflexes can also be tested. Pinprick sensation is tested with a safety pin, the sharp edge of a broken-off cotton swab, or special pins designed for the neurologic exam. Temperature sensation, mediated by the same pathway, is most easily tested with the side of a tuning fork, which, if freshly retrieved from an instrument bag, will be quite cold on the skin.
Vibration is tested by striking the Hz tuning fork and placing its stem against the joint being tested, typically beginning at the toes. Light touch is the least useful modality to test, because it is carried by a combination of pathways and is unlikely to provide clues to localization or diagnosis.
Finger-to-nose testing can identify the presence of dysmetria inaccuracy of targeting or intention tremor. Heel-to-shin testing can elicit incoordination in the lower extremities. Rapid alternating movements, rhythmic finger tapping, and heel tapping are particularly sensitive to coordination problems. Patients may have trouble with the timing or cadence of these movements.
Dysdiadochokinesis is the term used to describe difficulty with rapid alternating movements. In addition, certain diseases, such as Parkinson disease, have quite distinctive gaits associated with them. The patient with a normal stance maintains the feet at an appropriately narrow distance apart; a wide-based stance is abnormal. The Romberg sign is present when the patient maintains a steady stance with feet together and eyes open but sways and falls with feet together and eyes closed.
Its presence usually implies a deficit of joint position sense, not cerebellar function, as is commonly believed. Stride length should be full. Short-stepped or shuffling gaits are characterized by a decrease in stride length and clearance off the ground. Ataxia of gait results in an inability to walk in a straight line; patients may stagger from one side to the other or consistently list toward one side. Ataxia is typically associated with a wide-based stance. Ataxia can be brought out most obviously by having the patient attempt tandem gait, walking heel to toe.
The arms normally swing in the opposite direction from their respective legs during ambulation. Decreased arm swing is a feature of extrapyramidal disorders. Hydrocephalus is one etiology of such a gait disorder. It is produced by the choroid plexus of the ventricles and absorbed through the villi of the arachnoid granulations that project into the dural venous sinuses. CSF is produced continually at a rate of about 0. The entire CSF volume is thus replaced about every 5 hours.
LP is contraindicated by the presence of a space-occupying lesion that is causing mass effect, raised intracranial pressure, or local infection or inflammation at the planned puncture site.
Optimal positioning is the key to a successful and atraumatic LP. Ideally, a pillow should be placed between the legs, and the patient should lie on the edge of the bed where there is better support to keep the back straight. The anterosuperior iliac spine is at the level of the L vertebral interspace. The LP may be performed at this level, one interspace higher, or one to two interspaces lower. Remember that the spinal cord ends at the level of L The needle is inserted with the bevel facing upward, so that it will enter parallel to the ligaments and dura that it pierces rather than cutting them transversely.
The needle is directed slightly rostrally to coincide with the downward angulation of the spinous processes. The needle 10 is advanced gently until CSF is obtained. Fewer than five cells are present, and these are lymphocytes. Measured by LP in the lateral recumbent position, the opening pressure is about 60 to mm H2O. Xanthochromia refers to the yellow discoloration of the supernatant of a spun CSF sample.
Its presence helps to distinguish an in vivo intrathecal hemorrhage from a traumatic tap [in which red blood cells RBCs have not lysed and the supernatant is still colorless]. The implications of various CSF findings are summarized in Table The CSF findings in a variety of common conditions are summarized in Table Special tests may be performed as indicated.
Some examples include cytology for suspected malignancy, oligoclonal banding for suspected immune-mediated processes such as multiple sclerosis, 14,3,3-protein for Creutzfeldt-Jakob disease, and a variety of polymerase chain reactions and serologic tests for various infections. A computed tomography CT scan should be performed prior to an LP except in cases of suspected meningitis and when a CT scan cannot be performed. Low-pressure headache is the most common complication of lumbar puncture and is most effectively treated by having the patient lie flat and increase her intake of liquids and caffeine.
Rarely, it may be necessary to administer an epidural blood patch see Chapter Attenuation is defined simply as the removal by absorption or scatter of x-ray photons and is quantified on an arbitrary scale in Hounsfield units that is represented in shades of gray. Differences in the shades directly reflect the differences in the x-ray attenuation of different tissues, a property that depends on their atomic number and physical density.
Images are usually obtained in either an axial or a coronal plane. Three-dimensional reconstruction and angiography are possible with new-generation spiral CT scanners. Magnetic resonance imaging MRI is similar to CT in that radiant energy is directed at the patient and detected as it emerges from the patient.
MRI differs, however, in its use of radiofrequency RF pulses rather than x-rays. The images in MRI result from the varying intensity of radio-wave signals emanating from tissue in which hydrogen ions have been excited by an RF pulse.
A detailed understanding of magnetic resonance physics is not necessary for the interpretation of routinely used MRI sequences. It is sufficient to understand that the patient is placed in a magnet and that an RF pulse is administered. Signal intensity is measured at a time interval, known as time to echo TE , following RF administration. The RF pulse is administered many times in generating an image; the time to repetition TR is the time between these RF pulses.
Fat is bright on a T1-weighted image, which imparts a brighter signal to the myelincontaining white matter. Gadolinium is the contrast agent used in MRI, and gadolinium-enhanced images are usually acquired with a T1-weighted sequence. Contrast-enhanced images are invaluable in determining the presence of brain tumors, abscesses, other areas of inflammation, and new multiple sclerosis lesions see Fig.
It is very useful in assessing the chronic lesion burden in multiple sclerosis see Fig. A susceptibility-weighted sequence is one that is sensitive to the disruptive effect of a substance on the local magnetic field. Examples of substances that exert such a susceptibility effect are calcium, bone, and the blood breakdown products ferritin and hemosiderin. Areas of increased susceptibility appear black on these images. DWI demonstrates cellular toxicity with high sensitivity and is most commonly employed in the diagnosis of acute stroke, where it can be positive within half an hour of symptom onset.
The sensitivity of a CT scan for detecting lesions depends on many factors, including the nature and duration of the underlying disease process. The sensitivity for detecting areas of inflammation, infection, or tumor may be increased by the administration of intravenous contrast.
Contrast enhancement indicates local disruption of the blood-brain barrier. CT is the investigation of choice for demonstrating fresh blood.
Apart from providing better anatomic definition, MRI is particularly useful for imaging the contents of the posterior fossa and craniocervical junction, which are seen poorly on CT because of artifact from surrounding bone. DWI is the most sensitive technique available for demonstrating early tissue ischemia and is therefore extremely useful in the evaluation of patients with suspected stroke.
There is no cross-reactivity between the iodinated contrast agents used in CT and the gadolinium used as a contrast agent in MRI. When contrasted imaging is required, MRI may therefore be preferable when there is a history of allergy to intravenous contrast. Similarly, gadolinium does not have the nephrotoxicity of iodinated contrast.
MRI may be used safely only in the absence of metal objects foreign bodies, plates, and screws and pacemaker and defibrillator devices.
This is the most sensitive and specific imaging study of the intracranial and extracranial circulation. Risks of the procedure include contrast dye reaction, stroke due to plaque dislodged by the catheter, and bleeding from the cannulation site.
Compared with conventional angiograpy, MRA is less invasive and can be performed more quickly and less expensively, but it is not as sensitive or specific for cerebrovascular disease. MRA is performed commonly on the intracranial circulation of stroke patients to look for evidence of vascular narrowing or occlusion.
Magnetic resonance venography MRV can be used to demonstrate venous sinus thrombosis and other venous disease. Extracranial Doppler sonography measures blood flow by determining the difference between emitted and received ultrasound frequencies.
It is used commonly to detect stenosis or occlusion of the extracranial carotid circulation, especially in the planning stages for carotid endarterectomy. Transcranial Doppler TCD detects intracranial stenosis and emboli. Most of the intracranial circulation, however, is inaccessible to TCD. Although somewhat less accurate than MRA or conventional angiography, Doppler studies are noninvasive and virtually without contraindication.
Reproduced with permission from Patel PR. Lecture Notes: Radiology, 2nd ed. Hypermetabolism can be demonstrated during seizures though it is rare to get the scan during a seizure , while hypometabolic regions may be evident interictally. Such a finding can be very useful in planning epilepsy surgery, especially in the temporal areas.
Single-photon emission computed tomography SPECT uses a radioactive isotope to demonstrate increased blood flow during seizures. While regional patterns of abnormality help study disease processes, they are not specific enough for diagnosis in individual patients. Magnetic resonance spectroscopy is primarily a research tool used to demonstrate areas of neuronal damage or dysfunction and has been studied in the assessment of brain tumors, demyelinating disease, and infections of the CNS.
Normal EEG patterns are characterized by the frequency and amplitude of the recorded electrical activity, and the patterns of activity correlate with the degree of wakefulness or sleep. The normally observed frequency patterns are divided into four groups: alpha 8 to 13 Hz , beta 14 to 30 Hz , theta 4 to 7 Hz , and delta 0. Lower-amplitude beta activity is more prominent over the frontal regions.
Theta and delta activity is normal during drowsiness and sleep, and the different stages of sleep are defined by the relative proportions and amplitudes of theta and delta activity see Chapter The pattern in which these electrodes are connected to each other is referred to as the montage, of which there are essentially two types: bipolar and referential.
In a bipolar montage, all electrodes are active and a recording is made of the difference in electrical activity between two adjacent electrodes. In a referential montage, the electrical activity is recorded beneath the active electrode relative to a distant electrode or common average signal. The signal recorded by an EEG is a sum of excitatory and inhibitory postsynaptic potentials of cortical neurons.
First, the patterns of electrical activity recorded by the EEG are rarely if ever specific to their cause. For example, the presence of diffuse theta or delta activity during the awake state suggests an encephalopathy but does not indicate the etiology. Second, the EEG records the electrical activity of cortical neurons.
Although subcortical structures influence cortical activity, the surface EEG may be insensitive to dysfunction of deep structures. For example, seizures originating in the medial frontal or temporal lobes may not be readily apparent on the surface EEG.
Furthermore, the EEG provides a measure of the electrical activity of the cortex at the time of the recording and is therefore frequently normal in paroxysmal conditions such as seizures. The frequency of interictal EEG abnormalities may be higher in certain forms of epilepsy. Several common patterns of abnormal activity are recognized. Focal arrhythmic or polymorphic slow activity in the theta or delta range suggests local dysfunction in the underlying brain.
Generalized arrhythmic slow activity often indicates a diffuse encephalopathy. Interictal epileptiform findings include sharpand spike-wave discharges, with or without an accompanying slow wave.
Electrographic seizures may take various forms. The most common are rhythmic spike- or sharp- and slow-wave discharges or rhythmic slow waves. They may be focal or generalized. Activation procedures can be used to enhance the likelihood of finding abnormal EEG patterns: hyperventilation is useful for provoking EEG changes in patients with absence seizures, while photic stimulation can induce EEG changes in patients with myoclonic seizures.
The nerve is stimulated in at least two locations distal and proximal , and the distance between the two sites of stimulation is measured carefully. The distal latency, compound muscle action potential CMAP , and conduction velocity are recorded. The CMAP is a recording of the contraction of the underlying muscle. The distal latency is the time interval between stimulation over the distal portion of the nerve and the initiation of the CMAP.
Conduction velocity is calculated by measuring the difference in latency to CMAP initiation between proximal and distal sites of stimulation. For sensory studies, the nerve is stimulated at one site and the sensory nerve action potential SNAP is recorded either at a more proximal site orthodromic study or at a more distal site antidromic study.
Repetitive nerve-stimulation studies are used to demonstrate either decremental or incremental CMAP responses in disorders of the neuromuscular junction. Electromyography involves the insertion of a needle into individual muscles.
Recordings are made of the muscle electrical activity upon insertion insertional activity , while the muscle is at rest spontaneous activity , and during contraction volitional motor unit potentials. To increase the strength of muscular contraction, motor units can fire more quickly activation or more motor units can be added recruitment.
Reduced activation is seen in CNS disease. Reduced recruitment suggests a lower motor neuron lesion, while early recruitment can be seen in myopathic disease. For routine EMG studies, activity is recorded from a group of muscle fibers simultaneously. Singlefiber EMG is the technique used in the investigation of disorders of the neuromuscular junction.
For example, NCS and EMG may help to differentiate a C8—T1 radiculopathy from a lower brachial plexopathy or an ulnar neuropathy in the patient who presents with numbness of the fourth and fifth fingers and weakness of the hand. Similarly, the combination of motor NCS, repetitive nerve stimulation, and EMG may help to localize motor dysfunction i. In a patient with a polyneuropathy, NCS may help to define the relative degree of motor and sensory involvement and to distinguish primary demyelinating from axonal disease Table The fundamental principles behind the evaluation of a neurologic problem, however, should not be discarded.
On the contrary, an orderly and hypothesis-based approach may be even more important in a comatose patient than in others, given the need for timely diagnosis and the relative limitations on history and examination.
Typically the patient lies with eyes closed and does not open them even to vigorous stimulation, such as sternal rub, nasal tickle, or nailbed pressure. Alterations in consciousness short of coma are often described using terms such as drowsiness, lethargy, obtundation, and stupor, but these terms tend to be used imprecisely and it is generally best to describe simply how the patient responded to various degrees of stimulation. Its utility lies in its ease of use by nurses and paramedics, its interrater reproducibility, and its prognostic value following head injury.
An algorithm for approaching patients with coma or altered consciousness is presented in Figure The initial steps of stabilization and evaluation culminate in the neurologic exam, which is performed with two goals in mind: to assess brainstem function and to look for focal signs. The differential diagnosis and further investigations stem from this clinical assessment. Remember the ABCs. In any patient with altered consciousness, the airway, breathing, and circulation should be checked and maintained according to usual protocols, including intubation and mechanical ventilation if required.
Look for obvious clues to etiology. A brief history and general exam should be performed to search for obvious clues. The circumstances in which the patient was found can offer clues to the onset or etiology of depressed consciousness. The general exam may yield telling signs, such as an odor on the breath, needle tracks on the skin, or a tongue laceration.
It is important to check for meningeal signs in any unconscious patient because both bacterial meningitis and subarachnoid hemorrhage may lead to depressed consciousness. Try reversing common reversible etiologies. Most emergency rooms ERs make it standard practice to administer naloxone, thiamine, and dextrose to any patient with depressed consciousness and no obvious etiology.
Note that thiamine should always be given before glucose, because the latter can precipitate Wernicke encephalopathy if given alone. Check brainstem reflexes and look for focal signs. These are the two primary goals of the neurologic exam in this setting, because the subsequent diagnostic and therapeutic steps will depend on these clinical findings. Mental status testing in these patients begins with assessing the level of consciousness.
For example, does the patient lie with his or her eyes closed but open them slowly when spoken to in a loud voice? Does he or she groan but not open his or her eyes when sternal rub is applied? For many patients, further cognitive testing may not be possible. Cranial nerves should be examined in detail, because this is the portion of the exam most relevant to the assessment of brainstem function. In an arousable patient, most cranial nerves can be tested in the usual manner.
In a patient who is not arousable enough to follow commands, several important brainstem reflexes should be tested Table , including the pupillary, corneal, oculocephalic, and gag reflexes. In addition, a funduscopic examination should always be performed. For many patients with altered consciousness, testing for a blink to visual threat may be the only way to judge visual fields.
If the patient cannot move his or her face to command, the examiner may be restricted to looking for an asymmetry at rest, such as a flattened nasolabial fold on one side. The presence of an endotracheal tube may make such observation difficult. Motor tone should be checked in all extremities. If the patient can cooperate with some testing, a gross hemiparesis can be ruled out by having the patient hold the arms extended or legs elevated and observing for downward drift.
Otherwise, the examiner may be restricted to observing for asymmetry of spontaneous movements or to asking caretakers whether all extremities have been seen to move equally. Never assume the eyes are immobile unless caloric testing has been done. Both indicate brainstem dysfunction, although decorticate posturing suggests dysfunction slightly more superior than decerebrate posturing. Principles of Neural Science, 4th ed.
New York: McGraw-Hill, Decorticate and decerebrate posturing, signs of brainstem dysfunction, may be seen either spontaneously or in response to noxious stimuli Fig. Muscle stretch reflexes can be tested in the usual manner, and a Babinski sign should be sought. Sensory testing in most patients with altered consciousness is limited to testing of light touch or pain sensation.
Noxious stimulation to each limb, as described previously, may be useful in looking for gross sensory abnormalities. Coordination and gait may be tested in patients who are arousable enough. In theory, there are two main ways in which consciousness can be depressed: the brainstem can be dysfunctional or both cerebral hemispheres can be dysfunctional simultaneously.
In fact, acute disease in the brainstem e. Unilateral cerebral hemispheric lesions, however, can also lead to coma if they are large or severe enough to cause swelling and compression of the opposite hemisphere or downward pressure on the brainstem. Therefore most neurologists interpret the information obtained from the exam of the comatose patient using the following principle: the presence or absence of brainstem reflexes suggests how deep the coma is, while the presence or absence of focal signs narrows the differential diagnosis and guides the workup.
Thus, in milder cases of depressed consciousness, the pupillary, corneal, and gag reflexes may all be preserved. In more severe cases, some or all of these brainstem reflexes may be lost, no matter what the etiology. Note that if a brainstem reflex is abnormal in an asymmetric fashion, such as a unilateral unreactive pupil, this would be interpreted as a focal sign and suggests compression of or primary disease in the brainstem.
The presence of focal signs either on cranial nerve testing or in the remainder of the examination— including such findings as hemiparesis, aphasia, reflex asymmetry, facial droop, or a unilateral Babinski sign—suggests a structural cause of depressed consciousness Box The absence of focal signs suggests a diffuse cause of depressed consciousness, including metabolic, toxic, or hypoxicischemic etiologies Box Examples include coma from fulminant hepatic failure, barbiturate overdose, or anoxia following prolonged cardiac arrest.
The presence of focal findings on examination, suggesting a structural cause, demands urgent head imaging, almost always a noncontrast computed tomography CT scan. One should be looking for signs of a large acute stroke, an intracranial hemorrhage, or a mass lesion that may have enlarged rapidly or had hemorrhage within it.
Contrast-enhanced CT should be avoided if acute hemorrhage is possible. Even in cases where focal brainstem signs are found, the initial choice of head imaging may have to be a CT scan rather than magnetic resonance imaging MRI , despite the poor quality of the former in evaluating the brainstem, because of the possibility of a large cerebral hemispheric lesion compressing the brainstem as well as because of the more immediate availability of CT.
The absence of focal findings on examination, suggesting a diffuse cause, warrants an extensive workup for causes of metabolic, toxic, or infectious etiologies. Blood testing—including complete blood count CBC , electrolytes, glucose, liver function tests, and Other exogenous toxins carbon monoxide, heavy metals Infectious Meningitis bacterial, viral, fungal Diffuse encephalitis Hypoxic-ischemic Respiratory failure Cardiac arrest Other Subarachnoid hemorrhage Carcinomatous meningitis Seizures or postictal state toxicologic screen—may be necessary.
If infection is suspected, a chest x-ray, urinalysis, and blood or urine cultures may be called for. There should be a low threshold for obtaining a lumbar puncture LP. If a basic workup is unrevealing, one should search for more unusual causes such as myxedema coma, by checking thyroid function tests.
Of course, a head CT should be performed before obtaining an LP almost without exception in the evaluation of a patient with depressed consciousness, given the risk of precipitating brain herniation if a large intracranial mass particularly in the posterior fossa is present. If bacterial meningitis is suspected, empiric antibiotic treatment can be started if CT scanning is delayed.
Frequently, an electroencephalogram EEG is ordered in patients with coma or altered consciousness. Although many of its findings may be nonspecific, the EEG can help to assess how deep a coma is based on the degree of background slowing.
In addition, there are occasionally more specific patterns on EEG that suggest a particular diagnosis, such as hepatic encephalopathy or anoxic brain injury. Finally, the EEG can rule out nonconvulsive status epilepticus as a cause of coma in cases in which this is or is not clinically suspected. When increased intracranial pressure ICP is suspected clinically or radiographically, treatments aimed at lowering ICP should be applied.
These include raising the head of the bed, hyperventilation, and the use of an osmotic diuretic such as mannitol. Corticosteroids tend to be useful only in cases of edema associated with brain tumors. The lowering of ICP may be a neurologic or neurosurgical emergency if the patient shows signs of brain herniation, which is discussed in more detail in Chapter The prognosis of depressed consciousness is mostly dependent on etiology—the patient with a barbiturate overdose may recover completely, whereas one with a severe anoxic injury likely will not.
Age is an important prognostic factor as well. One of the most frequent reasons for admission to an intensive care unit ICU or neurologic consultation is to estimate the prognosis of a patient in coma following cardiopulmonary arrest. In these cases the circumstances and duration of the arrest are important, and published studies have correlated outcome with findings on neurologic examination performed at least 24 hours after the arrest.
Metabolic, infectious, or toxic etiologies require mostly medical management, while some structural causes of coma may require neurosurgical intervention. Usually a consequence of large lesions in the base of the pons, the locked-in syndrome leaves patients unable to move the extremities and most of the face.
If all other motor function is lost, they may be limited to communicating by vertical eye movements or blinks. BRAIN DEATH Death can be declared either when there has been irreversible cessation of cardiopulmonary function or there has been irreversible cessation of all functions of the entire brain, including the brainstem. A declaration of death based on the latter criterion is commonly referred to as brain death.
Many institutions have specific guidelines for how brain death must be determined, but in general the patient must be comatose, have absent brainstem reflexes, and have no spontaneous respirations even when the PCO2 has been allowed to rise the apnea test.
Confounding factors such as hypothermia or drug overdose must not be present. Local institutional guidelines for declaration of brain death should always be consulted. Most neurologists employ the terms confusion or encephalopathy, while delirium commonly used by psychiatrists often implies a state of encephalopathy characterized by a waxing and waning level of alertness.
At its core, an acute confusional state results from a problem of attention. Such inattention may be significant enough to make impossible the performance of more detailed mental status testing. Depending on the underlying etiology of the acute confusional state, other associated features may be present on neurologic or general physical examination as well. Differential Diagnosis The differential diagnosis of acute confusion includes a number of different disorders, among them aphasia particularly Wernicke , psychosis, and complex partial seizures.
Although patients with psychosis may also behave as if they were acutely confused, pure confusional states do not result in frank psychotic symptoms like hallucinations or delusions. Focal brain disorders, particularly acute right hemispheric lesions, can also lead to confusion. The appropriate diagnostic workup in a patient with confusion is therefore potentially quite extensive.
Blood work and urinalysis to search for infectious or metabolic disturbances are often warranted. Neuroimaging should be obtained if the neurologic history or examination suggests the possibility of an acute focal lesion.
An EEG can help to determine whether there is a widespread dysfunction encephalopathy or focal abnormalities. It is unlikely to demonstrate the precise cause of an acute confusional state but can help to confirm a diagnosis, since characteristic findings of an encephalopathy may be present.
The treatment and prognosis of acute confusional states depend largely on the underlying etiology. Most cases of confusion arise from a reversible underlying cause and will resolve if the underlying disorder is treated appropriately.
Confusional states arising from structural neurologic lesions or more chronic underlying disturbances may be less likely to improve spontaneously. Maximal interpretation of our environment is accomplished through the integration of visual, somatosensory, motor, and auditory information. This chapter covers the first two; the third constitutes part of higher cortical function, discussed elsewhere see Chapter ANATOMY Light enters the cornea and stimulates the rods and cones in the retina, where the visual stimuli are converted into electrical signals that are sent through the optic nerve to centers in the brain for further processing and visual perception.
The visual pathway with various field defects is shown in Figure The more posterior parts of the cerebral hemispheres are involved in seeing and analyzing visual information, including written language, and the more anterior parts control looking at and exploring visual space. Ninety percent of retinal axons terminate in a retinotopic fashion in the lateral geniculate nucleus, the principal subcortical structure that carries visual information to the cerebral cortex through the optic radiations.
This information is then transferred to associative visual cortex, including areas 18 and 19, and to many higher-order centers in the posterior parietal and inferior temporal cortices, where the perception of motion, depth, color, location, and form takes place. Other symptoms include eye pain, visual hallucinations, and oscillopsia.
Two important signs discussed in this chapter are the abnormal optic disc and anisocoria unequal pupils. Positive visual phenomena include brightness, shimmering, sparkling, hallucinations, shining, flickering, or colors, often suggesting migraine or seizures.
Negative visual phenomena can be described as blackness, grayness, dimness, or shade-obscuring vision, as seen in patients with strokes or transient ischemic attacks. When the complaint is loss of vision, ask the following questions: 1. Is this a monocular or binocular problem? Does the problem go away when one eye is closed? Does it affect a portion or the entire visual field?
Is it transient or persistent? Are there associated symptoms, such as headache, visual auras, motor or sensory disturbances, changes in mentation, seizures, or eye pain e. Diagnostic Evaluation The evaluation of acquired visual loss Box begins with determining whether the problem is at the level of the eye, optic nerve, chiasm, optic tract, lateral geniculate nuclei LGN , optic radiation, or occipital cortex.
Once the site of dysfunction is determined, the workup is targeted to the specific cause. The diagnostic evaluation includes assessment of visual acuity and color vision, test for afferent pupillary defects, testing of visual fields, and ophthalmoscopic evaluation. The ophthalmoscopic evaluation looks for damage to the retinal nerve fiber layer, optic atrophy, swollen disc, abnormal optic disc hypoplastic, tilted, etc.
To test visual acuity VA , use a distance chart with good illumination. At the bedside, the near chart handheld Snellen chart is often enough. If the VA is poor, try using a pinhole one can be created by making small holes in a blank card. If the pinhole test improves the VA, the problem is in refraction. If the patient is unable to read letters, try counting fingers, followed by perception of movement, and finally perception of a bright light.
Impairment of VA is usually a problem in the refractive apparatus of the eye or the optic nerve, or both. Rarely, chiasmal or retrochiasmal lesions cause changes in VA. Color vision is tested by using Ishihara plates. Another method is looking for red desaturation decreased perception of red color , which can be seen early in optic nerve problems particularly optic neuritis. The Textbook of Clinical Neurology is also available online. Readers will find the entire content on the website, along with test questions, case studies, guidelines and other additional material.
The textbook is designed for use in medical and paramedical training and is also suitable for programmes in nursing, human movement sciences, and medical biology. It serves as a reference for doctors and physiotherapists in clinical practice. A brief history of neurology The neurological consultation An overview of the nervous system and muscles.
Technical investigations in neurology Strength and sensation Motor control Brainstem and cranial nerves Autonomic nervous system, hypothalamus and pituitary gland The higher cerebral functions The visual system Cerebral meninges and the cerebrospinal fluid system The cerebrovascular system Diseases of the muscle and neuromuscular junction Disorders of the motor neurons, nerve roots and peripheral nerves Neurological pain syndromes Diseases of the Neurology. There is a download link below.
Click for download the book. Please bear in mind that we do not own copyrights to these books. Next, language is assessed. As noted previously, listening to the patient tell their history may be all that is necessary to gauge language ability. Formal testing, however, includes assessing the fluency of spontaneous speech, the ability to repeat, the ability to comprehend commands, the ability to name both common and less common objects, and the ability to read and write. For memory testing, most often the patient is given three words and asked to recall them several minutes later, with the aid of hints if necessary.
Visual memory can be tested with three simple shapes for the patient to draw from memory in several minutes. Visuospatial function can be tested in a variety of ways.
Patients can be asked to draw a clock, a cube, or another simple figure; alternatively, they can be asked to copy a complex figure drawn by the examiner Fig. Neglect is a mental status finding typically not sought by nonneurologists, yet its presence can be a very important sign.
Patients with dense neglect may fail to describe items on one side of a picture or of their surroundings, or may fail to bisect a line properly. Olfaction cranial nerve I is rarely tested, but when this is important, each nostril should be tested separately with a nonnoxious stimulus, such as coffee or vanilla.
Funduscopic examination is the only means by which a part of the central nervous system the retina can be directly visualized. The presence of nystagmus should be noted. Muscles of mastication V are tested by assessing strength of jaw opening and palpating over the masseters bilaterally while the jaw is clenched.
Facial sensation can be tested to all modalities over the forehead V1 , cheek V2 , and jaw V3. The afferent limb of the corneal reflex is mediated by this nerve. Muscles of facial expression VII are tested by having patients raise their eyebrows, squeeze their eyes shut, or show their teeth.
Though uncommonly tested, taste over the anterior two-thirds of the tongue is mediated by this nerve and can be evaluated with sugar or another nonnoxious stimulus. Hearing VIII may be evaluated in each ear simply by whispering or rubbing fingers; more detailed assessment of hearing loss may be accomplished with the Weber or Rinne tuning fork Hz test. Palatal elevation should be symmetric and the voice should not be hoarse or nasal IX and X.
Failure of the right palate to elevate implies pathology of the right glossopharyngeal nerve. The gag reflex is also mediated by these nerves. Sternocleidomastoid strength is tested by having the patient turn the head against resistance; weakness on turning to the left implies a right accessory nerve XI problem. The trapezius muscle is tested by having the patient shrug their shoulders. Tongue protrusion should be in the midline. If the tongue deviates toward the right, the problem lies with the right hypoglossal nerve XII.
The presence of fasciculations or of adventitious movements such as tremor or myoclonus should also be noted. Tone is one of the most important parts of the motor exam. Abnormalities of tone such as spasticity and rigidity are discussed in subsequent chapters.
Tone in the lower extremities can be tested well only with the patient supine. The examiner lifts the leg up suddenly under the knee; only in the presence of increased tone will the heel come off the bed. Finally, strength or power is assessed, by both functional observation and direct confrontation Fig. For each movement, the predominant muscle, peripheral nerve, and nerve root are given. Reproduced with permission from Ginsberg L.
Lecture Notes: Neurology, 8th ed. Oxford: Blackwell Publishing, — The patient may be asked to rise from a chair without using the arms or to walk on the heels or toes. Oxford: Blackwell Publishing, In the lower extremities, patellar knee jerk and ankle reflexes are the ones commonly tested. The adductor reflex can also be tested. The Babinski sign is sought by stroking the lateral sole of the foot while observing for extension of the great toe.
Clonus, if present, can be elicited by forcibly dorsiflexing the ankle when it is relaxed. In the upper extremities, the biceps, brachioradialis, and triceps reflexes are the ones commonly tested. Pectoral and finger flexor reflexes can also be tested. Pinprick sensation is tested with a safety pin, the sharp edge of a broken-off cotton swab, or special pins designed for the neurologic exam.
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