Professor of Neuroscience Department of Neuroscience University of California, San Diego La Jolla, California with. Jody Corey-Bloom, MD, PhD Professor of Neuroscience Department of Neuroscience University of California, San Diego La Jolla, California.
Robinson Singleton, MD Associate Professor
ADULT NEUROLOGIC EXAMINATION
Overall Goals
The Neurologic History
A close examination and additional tests such as electromyography (EMG) or X-ray examination may be necessary to clarify the diagnosis. In patients with chronic pain, including chronic daily headaches, factors such as anxiety and depression can worsen or intensify symptoms.
The Neurologic Examination
These areas are described in detail in Aids to the Examination of the Peripheral Nervous System (Medical Research Council 1975). As previously mentioned, it may be useful to test gait before the main part of the neurological examination as this plays a key role.
Basic Mechanisms
Evoked potentials are the time-locked electrical responses of the nervous system to a specific stimulus, such as The EEG signal represents changes in the transmembrane potential in the dendritic part of the neuron.
Recording Technology
The appearance of the EEG depends in part on the choice of filters used during recording. Changing the high-pass filter can reduce unwanted muscle artifacts and allow viewing of an EEG that is otherwise full of artifacts.
Normal EEG
Usually of low to moderate amplitude, it is seen in the central areas (electrodes C3 and C4) overlying the motor cortex. It can be the focus of any head region, although it is most often seen in the temporal regions.
Abnormal Patterns
In addition, special attention must be paid to ensuring that a sharp wave or spike in the area of the rupture rhythm is not overlooked as just a rupture artifact (Figure 2.6). the terms occasional or irregular may also be used) complete the basic classification scheme for abnormal EEG patterns. Even faster repetition rates of generalized spike-and-wave are seen in the family of 6-per-second spike-and-wave discharges.
EEG in the Differential Diagnosis of Epilepsy
A rare EEG finding is a central spike that occurs near the scalp in patients with epilepsy originating from anterior midbrain structures. Patients with TLE may present clinically with bouts of confusion, episodes of bizarre behavior, or panic attacks.
Epilepsy Surgery
Tremendous progress has been made in neuroimaging for epilepsy surgery, although video-EEG telemetry remains an important component of the evaluation. They can also be used to "map" the functions of the cortex underlying them, thereby improving surgical planning to avoid eloquent (language, motor function) cortex.
Computer EEG
The device can be easily implanted on an outpatient basis, with the output electrode attached to the left vagus nerve. This device is trained to detect abnormal electrocorticography determined to be associated with the patient's clinical seizures.
Evoked Potentials
A set of five consistently repeatable peaks comes from each of five structures along the auditory pathway: acoustic nerve (1.5–2.5 msec), cochlear nucleus (2–, 3 msec), superior olivary nucleus (3–4 msec), lateral lemniscus (4.5–5.5 msec) and the medial geniculate bodies of the thalamus (5.5–6.5 msec). Conductive hearing loss results in an increase in the hearing threshold without a change in central interpeak latencies.
Summary
Similar waveforms can be recorded in the other commonly tested nerves as the impulse travels along the specific path. Sensorineural hearing loss produces increased interpeak latencies as stimulus intensity is reduced, so that changes in the latency-intensity relationship can distinguish conduction deficits from neurological causes of hearing loss.
Acknowledgments
BAEPs are highly sensitive to acoustic nerve dysfunction from schwannomas, meningiomas, and other tumors of the cerebellopontine angle. Electrodiagnostic medicine is defined by the American Society of Electromyography and Electrodiagnosis as “the clinical and electrophysiological assessment of the function of nerve roots, peripheral nerves, neuromuscular junctions, muscles, spinal reflexes, and evoked potentials arising from the spinal cord and brain. ” This chapter focuses on the two most common electrodiagnostic techniques: nerve conduction studies (NCS) and electromyography (EMG).
Principles of Nerve Conduction Studies
Terminal or distal latency represents the integrity of the nerve from the point of stimulation to the axon terminals. CMAP latency is measured at the rise and corresponds to the fastest conducting nerve fibers.
Principles of Electromyography
In an orthodromic recording, stimulation of the digital sensory nerves elicits a response at a more proximal location along the nerve trunk. The amplitude varies from one MUAP to another, but is typically less than 2,000 µV for each of the first four MUAPs recruited.
Electromyographic Assessment of Denervation
Attention to the morphology of the motor units in a muscle with impaired recruitment provides information about both the chronicity of the injury and associated reinnervation. If the first voluntary effort always produces multiple motor units near the needle, a myopathy should be considered.
Electrodiagnosis of Specific Disorders
Electrodiagnosis makes use of the accessibility of both the median and ulnar nerves at the wrist. Peroneal conduction across the fibular head is delayed, and denervation of the anterior tibialis and extensor digitorum brevis is common.
Sensory Neuropathy
In more severe neuropathies, distal motor and sensory responses will often be absent, providing little information about the nature of the neuropathy. Sparing these muscles localizes the lesion to the upper trunk of the brachial plexus.
Neuromuscular Junction Disorders
Repetitive stimulation usually follows CMAP assessment and can be performed at any location where a well-defined CMAP can be obtained from only one muscle. Abnormalities in any of the above warrant further evaluation of the suspected disorder (eg, polyradiculopathy, myopathy, abnormalities of neuromuscular transmission).
Imaging Modalities
The amplitude of the induced current is proportional to the number of excited nuclei conducting a net magnetic vector. The induced current decay can be used to calculate relaxation parameters specific to each tissue type.
Problem-solving Approaches
Extraocular muscle abnormalities such as thyroid ophthalmopathy, metastases, and orbital pseudotumor, Figure 4.17 Infection. In the case of a meningioma, MRI is the best way to show the dural relationships of the tumor.
On the Horizon
Imaging for a spinal infection often begins with plain films of the spine, which may show early signs such as loss of disc space height or irregularity of the subchondral aspects of the vertebral endplates. Inflammation of the intradural nerve roots (polyradiculitis) with abnormal enhancement (Figure 4.15) can occur with HIV-related CMV.
COMMON PROBLEMS IN ADULT NEUROLOGY
If a diagnosis is not made immediately, the doctor must decide whether a potentially serious condition exists and the patient should be admitted for observation and a series of tests, or whether the patient can be safely discharged home and assessed on an outpatient basis . In addition, there is the question of what tests are needed to reach the correct diagnosis, in what order they should be performed to minimize the time and cost of an evaluation, or when it might be appropriate and safe to simply to diagnose. observe the patient without subjecting him to a laundry list of tests.
Definitions
The task of evaluating a patient who comes to the office or emergency room complaining of a momentary loss of consciousness, but who appears otherwise well at the time of the visit, makes many physicians uncomfortable. The goals of this chapter are to review the basic pathophysiological concepts involved in transient loss of consciousness, to apply these concepts to some common disorders, to understand when laboratory tests may be helpful in reaching a diagnosis, and to recognize when the patient's symptoms may be due to a potentially serious disorder that requires immediate attention.
Syncope
The patient's description of the event should always be corroborated by a reliable witness, if possible. Usually the patient gets out of bed in the middle of the night to go to the bathroom.
Seizures
Either type can evolve into a generalized tonic-clonic seizure, in which case it is called a partial seizure with secondary generalization. The diagnosis of an epileptic seizure depends on a detailed description of the event by the patient and a reliable witness.
Transient Loss of Consciousness of Unknown Etiology
An overview of the usefulness and indications of various diagnostic procedures and management options for specific causes of syncope. A comprehensive review of disorders associated with syncope; provides a critical analysis of current diagnostic procedures and a thoughtful approach to the study of syncope.
Anatomy and Physiology of the Vestibular System
Deflection of the hairs in the opposite direction causes hyperpolarization and a decrease in spontaneous firing rate. The vestibular nuclei are located in the brainstem at the base of the fourth ventricle.
History in the Dizzy Patient
Pathological imbalances in the vestibular system can be produced by impairments either in the vestibular inputs or in the central connections of the vestibular system. Useful aspects of the history in the differential diagnosis of vertigo are outlined in Table 6.2.
Examination of the Dizzy Patient
Spontaneous nystagmus is assessed by direct observation of the patient's eyes while the patient is. With all forms of peripheral vestibular nystagmus, nystagmus amplitude and frequency increase with gaze in the direction of the.
Diagnostic Tests
If extralabyrinthine inputs are not minimized by keeping the eyes closed and the arm outstretched, visual or proprioceptive cues will allow accurate target localization even if vestibular function is impaired. Patients with unilateral dysfunction usually stagger or fall on the side of the lesion, especially if the dysfunction is acute.
Treatment
In patients with acute persistent dizziness due to peripheral vestibular lesions, recovery occurs more quickly and completely when vestibular exercises are initiated as soon as possible after the onset of symptoms. In patients with acute persistent dizziness due to peripheral vestibular lesions, recovery occurs more quickly and completely when vestibular exercises are initiated as soon as possible after the onset of symptoms.
Selected Vertiginous Syndromes and Diseases
Due to the positioning of the head, the movement in step 2 is in the plane of the affected semicircular canal. Description of the head thrust test for bedside evaluation of unilateral loss of semicircular canal function.
Anatomy and Function
Traditionally, the cycle is considered to begin with the right heel striking the ground. The right foot bears weight from heel strike to right toe lift.
History and Examination
The left toe is then lifted and the left leg swings forward at the hip with knee flexion. The entire sequence from one contact of the right heel to the ground to the next right heel strike is a step.
Senile Gait
Tandem running consists of walking in a straight line, alternately placing one foot in front of the other and pressing the heel of the front foot against the toes of the other. Examining the wear pattern on the sole of the shoes may indicate altered foot placement or foot dragging.
Frontal Lobe Gait
Later sections focus on the most common walking problems that affect adults, especially the elderly. Normal pressure hydrocephalus usually presents with the triad of dementia, frontal gait disturbance, and urinary incontinence.
Spastic Gait
It is important to recognize NPH, as it is treatable with thecoperitoneal or ventriculoperitoneal shunting, but the classic triad of symptoms is actually more commonly seen in multi-infarct dementia. This is most often seen in conditions of cerebral palsy (in this entity, often identified as spastic diplegia) or cervical spinal cord injury.
Extrapyramidal Gait Disorders
Spastic quadriparesis requires damage to upper limb motor control (upper or lower motor neuron) in addition to the deficits listed above for spastic paraparesis. Chorea affects gait by interrupting normal gait with rapid, irregular movements of the limbs, turning of the neck, and twisting of the trunk and neck.
Cerebellar Ataxic Gait
A much more common cause of chorea in the elderly is chronic exposure to dopaminergic or antidopaminergic medications, although this is rarely severe enough to seriously affect gait (Table 7.6).
Sensory Ataxic Gait
Remember that the patient with cerebellar ataxia cannot stand with his feet together, even with his eyes open. Nineteenth-century physicians saw this entity often and called it "locomotor ataxia." In that era, the most common cause was tabes dorsalis, a neurosyphilitic degeneration of the dorsal root ganglia and posterior columns of the spinal cord.
Steppage Gait
This is because the patient with sensory ataxia has a small functional brain that is able to keep the patient on his feet as long as he continues to receive some information - such as visual input. But closing the eyes removes this source of input and the patient falls as the lack of proprioceptive information makes it impossible to tell where the feet or the floor are.
Myopathic Gait
Antalgic Gait
Functional Gait Disorders
Reviews common changes in gait in the elderly and frequent gait disorders seen in the elderly population. Wolff in the early 1930s that migraine and other headaches were studied in a systematic and scientific way.
General Clinical Approach
In both the emergency room and the general practitioner's office, there is rarely time to perform the detailed neurological examination usually reserved for the specialist. If there have been no recent changes in the patient's headache profile, the clinician may determine that it fits a well-defined pattern of one of the major headache syndromes.
Headache Syndromes
Because of the risk of severe vasoconstriction, triptans should not be used within 24 hours of ergotamine. The usual dose of 4-8 mg/day is most effective in the early course of the disease.
Symptomatic Headaches
Early in the development of the syndrome, there is pain in and around the TMJ. Many headache patients may have a weak TMJ, which is unrelated to the etiology of the headache.
Physiology of Pain
Its process extends from the skin, where it is equipped with a specialized receptor, to the dorsal horn of the spinal cord, where it synapses. Recently, a long-elusive specific nucleus for pain was identified in the ventrocaudal thalamus of the monkey.
General Principles of Pain Management
Transection of the dorsolateral funiculus of the spinal cord (which contains the projection of the descending modulatory system) does not abolish this phenomenon, and it is therefore thought to be mediated by propriospinal pathways. Perhaps the sensory cortex is involved in discriminative issues, while the cingulate cortex handles motivationally directed pain response, as the cingulate gyrus forms part of the motivational/emotional limbic system.
Acute Pain Management
The various etiologies of the disease may be related to a number of mechanisms, such as root compression, inflammatory pain, and spinal cord injury. The impact of pain on life dictates the intensity and direction of psychological and behavioral intervention, psychiatric drug treatment, and ultimately lifestyle change goals.
Chronic Pain Management
The primary goal of the program is a more meaningful and satisfying life for the patient. Second, the patient's lifestyle must be modified to integrate pain and stress management strategies.
Specific Syndromes
Burning pain in the distribution of the nerve is accompanied by a tingling sensation when the compression of the nerve increases. A bone scan may show diffuse uptake in the involved limb, supporting the third criterion.
Glossary of Pain Terms
The cornerstone hypothesis from which much of the modern understanding of pain mechanisms was derived. Complex regional pain syndrome (reflex sympathetic dystrophy) has not resolved within 6 weeks of the initial evaluation.
Sleep Architecture
Melatonin has been implicated as a modulator of light entrainment, as it is maximally secreted by the pineal gland ("hormone of darkness") during the night. Increasing understanding of the neurochemistry of sleep has given hope for more specific treatments of.
Sleep Disorders
Counselling, especially the promotion of good sleep hygiene practices, should be one of the first steps in the treatment of insomnia. In the last decade of the 20th century, benzodiazepines almost completely replaced barbiturates in the treatment of insomnia.
Definition and Importance
Clinical Features
Acutely confused patients may be fully alert, and especially in the early stages, attention is impaired out of proportion to changes in the level of arousal. Categories of affective disturbances in confused patients may include anger, anxiety, apathy, dysphoria, or euphoria.
Causes
These "long tract signs" indicate dysfunction of the corticospinal pathways, but do not necessarily indicate permanent structural damage. In fact, they are quite common in a variety of metabolic and toxic conditions, including hypocalcemia, hypomagnesemia, hepatic encephalopathy, and sedative withdrawal.
