What questions will I be asked (neurological history)?
History The patient provides the history. The history is the summary of the events leading up to the diagnosis. The history includes the time of the first symptoms, the progression of symptoms and the emergence of new symptoms over time.
The history of the presenting illness or chief complaint should include the following:
Symptom onset (short time ago vs. long-standing)
Course of the condition (static, progressive, or worse then better)
Associated symptoms such as imbalance, ringing in ear(s), hearing loss, seizures, headache, nausea, vomiting and pain
Pain should be further defined
Severity or quantity
The history includes the dates and descriptions of any medical procedures including surgery, radiation or chemotherapy.
The neurological examination allows the evaluation of specific function that is immediately relevant to the diagnosis. The neurologic examination includes mental status, cranial nerve, motor (strength), sensory (sensation), cerebellar (co-ordination), and gait examinations.
There are 12 cranial nerves. Some are named according to their function such as the olfactory (smell), optic (vision), oculomotor (eye movements), abducens (abduction of the eye), facial (facial expression), and vestibulo-cochlear or statoacoustic (hearing and balance).
The olfactory nerves consist of small unmyelinated axons that originate in the olfactory epithelium in the roof of the nasal cavity; they pierce the cribriform plate of the ethmoid and terminate in the olfactory bulb. Lesions of the nerve result in parosmia (altered sense of smell) or anosmia (loss of smell).
The common cold is the most frequent cause of dysfunction. Dysfunction can be associated with fractures of the cribriform plate of the ethmoid bone. Frontal lobe tumors may compress the olfactory bulb and or tracts and cause anosmia, but this is rare occurrence.
Olfactory function is easily tested by having the patient smell common objects such as coffee or perfume. Commercially available scented scratch papers may also be used.
The optic nerve is a collection of axons that relay information from the rods and cones of the retina. The temporal derivations reach the ipsilateral and the nasal derivations reach the contralateral superior colliculi and the lateral geniculate bodies. From there, axons extend to the calcarine cortex via the optic radiation.
The following testing is applied:
Acuity, using the Snellen's chart (near and distant vision)
Visual Field, by confrontation or if indicated by perimetry
Color, with a color (Ishihara) chart or by using common objects such as a multicolored tie or color accent markers.
Lesions of the visual pathways result in blindness and pupillary abnormalities, such as the Marcus-Gunn pupil (retinal or optic nerve disease), scotomata, and quadrant or hemianopsias (optic tract and radiation) and hemianopsias with macular sparing (calcarine cortex).
The oculomotor nucleus of the nerve is located in the midbrain and innervates the pupillary constrictors; the levator palpebrae superioris; the superior, inferior and medial recti; and the inferior oblique muscles. Lesions result in paralysis of the ipsilateral upper eyelid and pupil, the inability to adduct and look up or down. Frequently, the eye is turned out (exotropia). In subtle cases, patients complain only of diplopia or blurred vision.
The exotropia seen in 3rd nerve paralysis can be distinguished from that in internuclear ophthalmoplegia because in the latter, convergence is preserved.
Paralysis of the third nerve is the only ocular motor nerve lesion that results in diplopia in more than one direction, thus distinguishing itself from 4th nerve paralysis (which also can result in exotropia). Pupillary involvement is an additional clue to involvement of the 3rd nerve. Pupil-sparing 3rd nerve paralysis occurs in diabetes mellitus, vasculitides of other etiologies and certain brainstem lesions.
The nucleus of the nerve is located in the midbrain; it innervates the superior oblique muscle, which incycloducts and infraducts the eye. Typically, the trochlear allows viewing of the tip of the nose.
An isolated right superior oblique paralysis results in exotropia to the right (R), and double vision that increases on looking to the (L) and by head tilt to the right (R). The mnemonic is R, L, R (the "marching rule").
The rule is L, R, L for left superior oblique paralysis. This rule and the lack of ptosis and/or pupillary involvement makes it easy to distinguish the exotropia of 4th nerve paralysis from that seen in 3rd nerve paralysis.
The nucleus of the nerve stretches from the midbrain (mesencephalic n.) through the pons (main sensory nucleus and motor nucleus) to the cervical region (spinal tract of the trigeminal nerve). It provides sensory innervation for the face and supplies the muscles of mastication.
Paralysis of the first division (V1) is usually seen in the superior orbital fissure syndrome and results in sensory loss over the forehead along with paralysis of the 3rd and 4th nerves.
Paralysis of the second division (V2) results in loss of sensation over the cheek and is due to lesions of the cavernous sinus; it also results in additional paralysis of V1 and the 3rd and 4th nerves.
Isolated V2 lesions result from fractures of the maxilla. Complete paralysis of the 5th nerve results in sensory loss over the ipsilateral face and weakness of the muscles of mastication. Attempted opening of the mouth results in deviation of the jaw to the paralyzed side.
The nucleus of the nerve is located in the paramedian pontine region in the floor of the fourth ventricle. It innervates the lateral rectus, which abducts the eye. Isolated paralysis results in esotropia and inability to abduct the eye to the side of the lesion.
Patients complain of double vision on horizontal gaze only. This is referred to as horizontal homonymous diplopia, which is the sine qua non of isolated 6th nerve paralysis.
Although it is considered a pure motor nerve, it also innervates a small strip of skin of the posteromedial aspect of the pinna and around the external auditory canal. The nervus intermedius of Wrisberg conducts taste sensation from the anterior two-thirds of the tongue and supplies autonomic fibers to the submaxillary and sphenopalatine ganglia, which innervate the salivary and lacrimal glands.
A lower motor neuron lesion (LMNL) of the nerve, also known as peripheral facial paralysis, results in complete ipsilateral facial paralysis; the face draws to the opposite side as the patient smiles. Eye closure is impaired, and the ipsilateral palpebral fissure is wider.
In an upper motor neuron lesion (UMNL), also known as central facial paralysis, only the lower half of the face is paralyzed. Eye closure is usually preserved.
In peripheral facial paralysis, a different type of clinical presentation is seen with four different levels of nerve lesion.
A) Lesions of the meatal or canalicular segment.
Facial paralysis with hearing loss, and loss of taste in the anterior two-thirds of the tongue, imply lesions in the internal auditory canal from fracture of the temporal bone or at the cerebellopontine angle form compression by tumors.
B) Lesions of the labyrinthine or fallopian segment.
Lesions that spare hearing (with hyperacusis) indicate lesions further down the course of the nerve.
Loss of taste in the anterior two-thirds of the tongue and loss of tearing imply lesions that involve the chorda-tympani and the secretomotor fibers to the sphenopalatine ganglion in the labyrinthine segment, proximal to the greater superficial petrosal nerve (GSPN). Distal to GSPN lacrimation is normal, but hyperacusis is still present. Geniculate lesions in this segment cause pain in the face.
C) Lesions of the horizontal or tympanic segment.
The lesion is proximal to the departure of the nerve to stapedius and results in hyperacusis, loss of taste in the anterior two-thirds of the tongue, and facial motor weakness.
D) Lesions of the mastoid or vertical segment.
Hyperacusis is present if the lesion is proximal the nerve to stapedius. It is absent if the lesion is beyond the nerve to stapedius and only loss of taste and facial paralysis occur. If the lesion is beyond the chorda tympani in the vertical segment (as in lesions of the stylomastoid foramen), taste is spared and only facial motor paralysis is seen.
The vestibulo-cochlear or statoacoustic nerve enters the brainstem at the pontomedullary junction and contains the incoming fibers from the cochlea and the vestibular apparatus forming the eighth cranial nerve. It serves hearing and vestibular functions, each of which will be described separately.
Hearing loss is divided into conductive and sensorineural. Three different tests help evaluate the auditory component of the nerve.
In Weber's test, a vibrating tuning fork is held over the forehead in the midline. The vibrations are normally perceived equally in both ears because bone conduction is equal. In conductive hearing loss, the sound is heard louder in the abnormal ear. In sensorineural hearing loss, lateralization occurs to the normal ear. The sensitivity of the test can be increased (up to 5 dB) by having the patient block his or her external ear canals by placing the fingers at the introiti.
In Rinne's test, the vibrating tuning fork is placed over the mastoid region until the sound is no longer heard; it is then held against the ear. Normally, the sound should continue to be heard. In conductive hearing loss, this will not be the case, since bone conduction in that case is better than air conduction. In sensorineural hearing loss, both air conduction and bone conduction are decreased to a similar extent.
In Schwabach's test, the patient's hearing by bone conduction is compared with the examiner's hearing, by placing the vibrating tuning fork against the patient's mastoid process and then to the examiner's. If the examiner can continue to hear after the patient has stopped hearing, then hearing loss is suspected.
The vestibular portion of the nerve enters the brainstem along with the cochlear portion. It transmits information about linear and angular accelerations of the head from the utricle, saccule and the semicircular canals of the membranous labyrinth to the vestibular nucleus. Linear acceleration is monitored by the macules in the utricles and saccules; angular acceleration is monitored by the cristae contained in the ampullae in the semicircular canals. These signals reach the superior (Bechterew's), lateral (Deiters') medial (Schwalbe's) and inferior (Roller's) nuclei and project to the pontine gaze center through the medial longitudinal fasciculus (MLF); to the cervical and upper thoracic levels of the spinal cord through the medial vestibulospinal tract; cervical, thoracic and lumbosacral regions of the ipsilateral spinal cord through the lateral vestibulospinal tract; and to the ipsilateral floculo-nodular lobe, uvula and the fastigial nucleus of cerebellum through the vestibulocerebellar tract.
The Romberg test evaluates vestibular control of balance and movement. When the feet are placed together and the eyes are closed, the patient will tend to fall towards the side of vestibular hypofunction. When asked to take steps forward and backward, the patient progressively deviates to the side of the lesion.
The Romberg test may also be positive in patients with polyneuropathies, but such people do not consistently fall to one side as in patients with vestibular dysfunction. Another test is to ask the patient to touch the examiner's finger with the patient's hand above the head. Consistent past pointing occurs to the side of the lesion. Provocative tests include the Nylen-Barany test and caloric testing.
The nucleus of the nerve lies in the medulla and is anatomically indistinguishable from the 10th and 11th cranial nuclei (nucleus ambiguous). Its main function is sensory innervation of the posterior third of the tongue and the pharynx. It also innervates the pharyngeal musculature, particularly the stylopharyngeus in concert with the vagus nerve.
Vascular stretch afferents from the aortic arch and carotid sinus, as well as chemoreceptor signals from the latter, travel in the nerve of Herring to join the glossopharyngeal nerve; they reach the nucleus solitarius, which in turn is connected to the dorsal motor nucleus of the vagus and plays a part in the neural control of blood pressure.
Lesions affecting the glossopharyngeal nerve result in loss of taste in the posterior one-third of the tongue; and loss of sensation of pain and touch in the same area, soft palate and the pharyngeal walls. The 9th and 10th cranial nerves travel together, and their clinical testing is not entirely separable. Therefore, their examination will be discussed with that of the vagus nerve.
Starting in the nucleus ambiguous, the vagus nerve has a long and tortuous course providing motor supply to the pharyngeal muscles (except the stylopharyngeus and the tensor veli palati), palatoglossus, and larynx. Somatic sensation is carried from the back of the ear, the external auditory canal; and parts of the tympanic membrane, pharynx, larynx and the dura of the posterior fossa. It innervates the smooth muscles of the tracheobronchial tree, esophagus and the GI tract up to the junction between the middle and lateral thirds of the transverse colon.
The vagus provides secretomotor fibers to the glands in the same region and inhibits the sphincters of the upper GI tract. Along with visceral sensation from the same region, the nerve participates in vasomotor regulation of blood pressure by carrying the fibers of the stretch receptors and chemoreceptors (aortic bodies) of the aorta and providing parasympathetic innervation to the heart.
The pharyngeal gag reflex (tongue retraction and elevation and constriction of the pharyngeal musculature on touching the posterior wall of the pharynx, tonsillar area or the base of the tongue) and the palatal reflex (elevation of the soft palate and ipsilateral deviation of the uvula on stimulation of the soft palate) are decreased in paralysis of the 9th and 10th cranial nerves. In unilateral 9th and 10th nerve paralysis, touching these areas results in deviation of the uvula to the normal side.
Unilateral paralysis of the recurrent laryngeal branch of the 10th cranial nerve results in hoarseness of voice. Bilateral paralysis results in stridor and requires immediate attention, to prevent aspiration and its attendant complications.
From the nucleus ambiguous, the nerve joins the vagus nerve in forming the recurrent laryngeal nerve to innervate the intrinsic muscles of the larynx. The spinal portion of the nerve arises from the motor nuclei in the upper five or six cervical segments, enters the cranial cavity through the foramen magnum and exits through the jugular foramen, and provides motor innervation to the sternocleidomastoid (SCM) and the mid and upper thirds of the trapezius.
In testing symmetry of the SCM and the trapezius muscles should be evaluated. Have the patient push the face against resistance to the right and to the left. When the right SCM is weak, pushing to the opposite (left) side is impaired and vice versa. Shrugging of the shoulder is impaired ipsilaterally when the trapezius is weak.
The nucleus of this nerve lies in the lower medulla, and the nerve itself leaves the cranial cavity through the hypoglossal canal (anterior condylar foramen). It provides motor innervation for all the extrinsic and intrinsic muscles of the tongue except the palatoglossus. To test the hypoglossal nerve, have the patient protrude the tongue; when paralyzed on one side, the tongue deviates to the side of paralysis on protrusion.
The cerebellum provides an important feedback loop for coordination of muscle activity by integrating the functions of the cortex, basal ganglia, the vestibular apparatus, and the spinal cord. Midline cerebellar dysfunction results in ataxia of gait, difficulty in maintenance of upright posture, and truncal ataxia. Acute neocerebellar hemispheric lesions result in additional signs. The following are various cerebellar signs:
Ataxia, atonia, and asthenia
Dysarthria (staccato, slurred, or scanning speech)
Gait is tested by having the patient walk normally and at tandem. In the latter, the patient is asked to walk with one foot immediately in front of the other (heel-to-toe). A tendency to sway or fall to one side indicates ataxia, suggesting ipsilateral cerebellar dysfunction. Atonia and asthenia can occur in other lesions of the nervous system and are not specific to the cerebellum; their testing is described elsewhere.
Intention tremor refers to an oscillating tremor that accelerates in pace on approaching the target. Dyssynergia or incoordination results in loss of smoothness of execution of a motor activity. Dysmetria results in overshooting or undershooting of a target while attempting to reach an object. All three of these can be elicited by having the patient attempt to alternately touch his or her nose and/or the examiner's finger.
Dysrhythmia refers to the inability to tap and keep a rhythm. It can be tested by tapping the table with a hand (or the floor with a foot) and asking the patient to repeat the maneuver. Dysdiadochokinesis is the inability to perform rapid alternating movements; it can be tested by asking the patient to tap one hand on the other (or on the thigh) repeatedly while simultaneously pronating and supinating the hand. Various combinations of the above signs appear, depending on the extent and location of the lesion in the cerebellum.
If a specific treatment is recommended, the patient and the physician discuss the risks and benefits of the treatment. The proposed treatment should be compared to other forms of treatment in terms of risk to normal function, potential complications of the different treatments, the rate of recurrence of the treated tumor, and the possible treatments if there should be recurrence. The option of doing nothing is discussed as well.
For informed consent, the patient should know the risks and benefits of all of the different treatments, not just the one that may be pursued.