Localization



Localization





There are three questions that have to be answered in assessing every patient with possible neurologic disease. These must be answered in order, or it is difficult to make an appropriate diagnosis in each case.


QUESTION 1: IS THIS A NEUROLOGIC PROBLEM?

On occasion neurologists are called to see patients with problems outside of their area of expertise. A patient with a conversion disorder who cannot move his or her leg, a patient who feels faint due to hyperventilation syndrome, and a patient who cannot walk due to malingering all have in common neurologic symptoms, but ultimately a diagnosis that is non-neurologic. None of these patients will benefit from an exhaustive neurologic evaluation, but all will benefit from appropriate supportive and therapeutic activities. Consider whether the condition is neurologic in the initial evaluation of the patient.


QUESTION 2: WHERE IN THE NERVOUS SYSTEM IS THE PROBLEM?

Where the problem is located in the nervous system is a crucial question for neurologic disorders. Without understanding where in the nervous system the problem is, one cannot understand the cause of the disorder or move forward in therapy. Lesions can either be located at a level in the nervous system (e.g., cortex, brainstem, peripheral nerve), or affect a particular neurologic system (e.g., cerebellar disorder, motor system disorder). Some diseases affect different locations in the nervous system (e.g., multiple sclerosis). Once the location of the problem is known, this guides the evaluation of the possible etiology or mechanism of the problem.

A working knowledge of basic neuroanatomy helps in localizing problems in the nervous system. Understanding the anatomy of the major ascending and descending pathways (spinothalamic tract, dorsal columns, corticospinal tract), the major cranial nerves and their brainstem connections, the visual system, and the major
anatomic areas of the cortex (language areas, sensory cortex, visual cortex, motor cortex) assists in localizing lesions in the central nervous system. A working knowledge of the major root, plexus, and peripheral nerve anatomy allows effective localization of peripheral nervous system disorders.

Each level or system within the nervous system has characteristic symptoms and signs. When listening to the history or examining the patient, the examiner should consider how the signs and symptoms correlate with different nervous system locations (Table 1.1).








TABLE 1.1. Localization of Symptoms and Signs in the Nervous System































































Location

Typical Symptoms

Typical Signs


Cortex

Cognitive, visual, language, neglect, behavior, motor, sensory, seizures, myoclonus

Field cut, aphasia, neglect, cortical sensory loss, apraxia, dementia


Brainstem

Diplopia, dysarthria, imbalance, facial weakness or numbness, weakness, altered consciousness

Combination of cranial nerve findings and long tract findings


Spinal cord

Sensory and motor symptoms below a level, bowel and bladder symptoms, stiff legs

Sensory level, motor and sensory deficits below level, reduced anal reflexes, hyperreflexia below level and upgoing toes


Nerve root

Pain down root distribution, weakness, numbness limited to root involved

Weakness, sensory loss, and reflex loss in root distribution


Plexus

Focal weakness usually in shoulder girdle or hip girdle muscles on one side,with sensory loss

Weakness of proximal muscles on one side, sensory loss in similar area not in root distribution, reflex loss


Peripheral nerve

For generalized neuropathy sensory symptoms in feet and hands, weakness, imbalance. For focal neuropathy weakness, numbness, pain in nerve distribution

“Stocking and glove”sensory loss feet + hands, decreased reflexes, distal weakness. For focal neuropathy weakness, sensory loss, reflex loss in nerve distribution


Neuromuscular junction

Fluctuating weakness, usually proximal, diplopia, dysphagia, neck weakness. No sensory symptoms or bowel and bladder symptoms

Fatigable weakness of various muscles, normal reflexes, sensory, and other neurologic examination


Muscle

Weakness, usually difficulty arising from chairs, going up stairs, combing hair

Weakness of muscles, atrophy, otherwise normal neurologic examination


System Involved

Symptoms

Signs


Motor

Weakness, spasticity, muscle twitching, dysphagia

Hyperreflexia, hyporeflexia, fasciculation, atrophy, weakness, upgoing toe


Sensory

Tingling, burning, sensory loss, unsteady gait, difficulty feeling things

Loss of pin, touch, temperature, position, vibration sensation, reflex loss


Autonomic

Blurred vision, dry mouth, loss of sweating, bowel and bladder dysfunction, postural lightheadedness

Altered pupil responses, postural hypotension, loss of R-R variability, altered gastric motility, altered sweating


Basal ganglia

Gait disorders, unusual limb movements, dysphagia, dysarthria

Parkinsonian symptoms, choreoathetosis, hemiballismus


Cerebellar

Unsteadiness, incoordination, slurred speech

Ataxic gait, nystagmus, incoordination, intention tremor, reduced reflexes

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Oct 20, 2016 | Posted by in NEUROLOGY | Comments Off on Localization

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