Alteration in mood is a common sign of neurological disease, as a result of either the pathological process itself or of the patient’s awareness of the disease. Although depression is most common, euphoria or mood swings may occur with disease of the frontal lobes of the brain.

Motor abnormalities

Symptoms expressed in the limbs and trunk that may indicate neurological disease include weakness and wasting of muscles, clumsiness, and unwanted movements. Weakness or clumsiness may be caused by diseases of the cerebellum, basal ganglia, or peripheral nerves. Involuntary and repetitive movements of the body may be due to a number of disorders including Huntington disease and cerebral palsy.

Pain

Although the central nervous system is not supplied with sensory fibres that report sensations of pain, severe pain can result from thalamic strokes. Neuralgia, or attacks of pain along the sensory nerves, are caused by irritation of some of the cranial nerves or spinal roots. Also, many disorders affecting the peripheral nerves and muscles are painful.

Change in sensation

Alterations of sensation may be positive or negative; the former include tingling, burning, itching, and pain, while the latter consist of diminution or loss of some or all sensations. Sensations carried by large, heavily myelinated fibres, such as position, discriminative light touch, and vibration, tend to be affected together, as do those carried by the smaller, thinly myelinated or nonmyelinated fibres, including pain, crude light touch, and temperature.

Higher cerebral functions

Tests of concentration, of recent and remote memory, of language, and of ability to follow simple spoken or written commands are usually given in order to evaluate the patient’s orientation in place and time. Comprehension, reasoning, and planning can be tested, for example, by asking about the similarities and differences between two objects (e.g., child and dwarf, wall and fence) or by asking the patient to explain the message or moral contained in a proverb (e.g., “People in glass houses should not throw stones”).

If cortical disease is suspected, tests for apraxias, aphasias, and agnosias; tests measuring the ability to draw and copy simple figures; and writing tests are performed. Standardized tests for examining these functions apply quantitative measurements to any deficit, which can be analyzed further by more sophisticated psychological testing.

The physician examines the head and neck, looking especially for local tenderness or deformity and for evidence in children of enlargement of the head, which may suggest hydrocephalus. The physician may also use a stethoscope to listen to the major blood vessels in the neck or the skull for sounds indicating unusual communication between arteries and veins. Irritation of the meninges, which may occur with intracranial infection or bleeding, leads to unusual stiffness on passive attempts to flex the neck, as well as to an inability to straighten the bent knee when the hip is flexed (the Kernig sign).

Cranial nerves

The physician tests the olfactory nerve by placing items with specific, mild odours, such as coffee, tar, or lemon, under the nose of the patient. The patient should be able to perceive, though not necessarily identify, the odour if the olfactory nerve is functioning correctly.

An ophthalmoscope is used to test the optic nerve and to see the optic disk, the retinas, and the small arteries and veins that lie upon them. Visual acuity is tested with a standard eye chart, and the visual field is examined by asking the patient to signal when he sees an object brought in toward the centre of vision from the periphery. An instrument called a perimeter may be used to determine the central and peripheral visual fields.

The physician tests the three oculomotor nerves (oculomotor, trochlear, and abducens) together by asking the patient to gaze in different directions on command and to follow a moving object with the eyes only. The shape, size, and reactivity of the pupils—both to light and to close objects—are also tested. The upper eyelid is also examined for signs of drooping.

The physician examines motor functions of the trigeminal nerve by asking the patient to clench the teeth and by tapping the patient’s chin to test the jaw reflex. This is one of the few physiological reflexes that is normally not detected. The sensory functions of the nerve are examined by stimulating the face gently with the finger or cotton for light touch, cold steel for temperature, and a pin for scratch or pain sensation. This procedure is done for the three anatomical divisions of the nerve on each side of the face. Finally, cotton is touched to the cornea to assess the corneal reflex. Normally, an abrupt blink is produced.

The functions of the facial nerve are examined by the patient’s ability to close the eyes tightly, to bare the teeth, and to attempt to whistle. The facial nerve also carries fibres subserving the function of taste on the front of the tongue, so weak solutions of sugar, salt, lemon, or vinegar can be used to test its function. (Flavour—as opposed to the tastes of sweetness, saltiness, bitterness, and sourness—is largely mediated by the olfactory nerve.)

To examine the cochlear nerve, hearing tests are used to determine the patient’s overall acuity to the whispered voice. The Rinne test differentiates the patient’s ability to hear the hum of a tuning fork held both beside the ear and on the mastoid bone of the skull behind the ear. If the sound is louder at the latter site, impairment of the conduction of vibrations through the three small bones in the middle ear is likely, while if the former sound is louder, any deafness is likely due to disease of the inner ear or of the cochlear nerve. The Weber test consists of placing the tuning fork on the forehead; the sound is better perceived either in the ear without nerve deafness or, paradoxically, in the ear affected by mild middle-ear deafness. Further testing may be performed in an audiometry laboratory.

Tests of the vestibular nerve are not routinely performed. The usual screening procedure is to tip the patient’s head back and down 45 degrees and await the appearance of vertigo or nystagmus. Further testing may be performed in a laboratory and includes the irrigation of the external ear canals with warm or cool air or water, rotation of the patient, and instruction of the patient to gaze in various directions to assess nystagmus.

To examine glossopharyngeal and vagus nerve function, the physician tests for the presence of touch sensation on the soft palate and the back of the throat (the latter usually eliciting a gagging reflex), the elevation of the palate on phonation (which should be symmetrical but rises to the stronger side in the presence of weakness on one side), the quality and loudness of the voice, and the normal slowing of the heartbeat when one carotid artery is compressed in the neck.

The sternocleidomastoid and trapezius muscles, supplied by the accessory nerve, are tested by the patient pushing his head forward and shrugging his shoulders upward against the physician’s resistance.

Atrophy and weakness of the tongue muscles supplied by the hypoglossal nerve can be assessed by measuring the deviation of the tongue when extended toward the weak side.