Palsy of cranial nerves can affect both a single cranial nerve and several of them. Damage to the cranial nerves can be caused, among others, by taste disturbances, but also limited mobility of the neck or hearing impairment. So what symptoms should lead to a suspicion of cranial nerve palsy and direct us to visit a neurologist?

Paralysis of cranial nervesmay affect any of the 12 pairs of cranial nerves, while the symptoms of pathological processes related to these structures, which are palsies of cranial nerves, are much more distinguished. There are two main groups of nerves in the body: spinal nerves and cranial nerves. In the case of the latter, 12 pairs of cranial nerves are replaced. These nerves carry all possible types of fibers, both sensory and motor fibers and fibers of the autonomic system (sympathetic and parasympathetic). The cranial nerves are responsible for transmitting signals related to the senses (e.g. sight or hearing) or sensory stimuli (e.g. touch) that are involved. they are also in the control of the motor activity of the muscles (e.g. the muscles of the jaw or tongue). They also involve phenomena independent of our will, subject to the control of the autonomic system - for example, the constriction and expansion of the pupil of the eye or the secretion of saliva by the salivary glands. . There are many potential causes of cranial nerve palsy, examples include:

  • injuries - both head and neck injuries
  • intracranial hematomas
  • cavernous sinus thrombosis (part of the cranial nerves is leaking in its vicinity)
  • strokes
  • aneurysms of the cerebral vessels
  • amyotrophic lateral sclerosis
  • neoplastic diseases (when the tumor invades elements of a given nerve)
  • inflammatory processes within the brain
  • diabetes
  • syphilis
  • multiple sclerosis

Palsy of the cranial nerve can also occur spontaneously for no apparent reason. This is the case with one form of facial nerve palsy, known as Bell's palsy.

Paralysis of cranial nerves: olfactory (I) nerve

As indicated by herselfname, the function of the first cranial nerve is to perceive olfactory sensations. Paralysis of the olfactory nerve results in the loss of the sense of smell, i.e. anosmią.

Paralysis of cranial nerves: optic (II) nerve

The optic nerve is responsible for the sense of sight. The symptoms of damage and the associated paralysis of the optic nerve depend on which part of the optic nerve is affected by the pathology. If the optic nerve itself is damaged, one eye becomes blind. Optic nerve fibers can also be damaged in the place where they cross, i.e. in the central part of the so-called visual intersection. If this happens, the patient experiences bilateral hemi-vision (cannot see the image from the side of the field of view of both eyes).

Paralysis of cranial nerves: oculomotor (III) nerve

The third cranial nerve is involved, inter alia, in in the control of eyelid movement, it is also responsible for the movement of the oculomotor muscles and for the activity of the pupil. The paralysis of the oculomotor nerve causes the upper eyelid to drop. Additionally, in patients, the eyeball is directed outwards (its abduction) and the pupil is dilated. When the third cranial nerve is paralyzed on the side of the lesion, pupillary reflexes are abolished.

Paralysis of cranial nerves: block (IV) nerve

The block nerve is another cranial nerve responsible for the movement of the eye muscles. His paralysis results in double vision (diplopia, which occurs especially when looking down), additionally, the eyeball rotates inwards (i.e., to its adduction) and upwards, which results in convergent strabismus.

Paralysis of cranial nerves: trigeminal (V) nerve

The fifth cranial nerve is involved in receiving sensory stimuli from many regions of the head, and in addition, it controls the activity of many different muscles in this area of ​​the body. Palsy of the trigeminal nerve is manifested by disturbances in the sensation of the face (it can even lead to a complete loss of sensation), paresthesia may also appear (tingling sensation, numbness). Another effect of trigeminal nerve palsy is paralysis of the muscles of the temporomandibular joint, which is associated with the appearance of a characteristic symptom - when opening the mouth, the patients' jaw shifts towards the existing nerve damage. In the course of the trigeminal nerve palsy, the corneal and conjunctival reflexes are also abolished.

Paralysis of cranial nerves: abduction nerve (VI)

The abduction nerve is another nerve that is involved in the movements of the eyeball. His paralysismanifested by the rotation of the eyeball inwards (the patient has a strabismus), additionally there may be diplopia.

Paralysis of cranial nerves: facial nerve (VII)

The seventh cranial nerve innervates the facial muscles, it is also one of the nerve structures involved in the perception of taste stimuli. Facial nerve paralysis can manifest itself in two ways - the nature of the symptoms in the case of pathologies affecting this nerve depends on where the damage occurred. paralysis of the facial mimic muscles on the side of the lesion. The patient cannot wrinkle his forehead, close his eye or grin his teeth, the mouth corner also droops. The mentioned may be accompanied by taste disturbances in 2/3 of the front part of the tongue and suppression of tear production. Central paralysis of the facial nerve (i.e. where the defect affects the nuclei of the nerve, located in the brainstem) results in the appearance of symptoms on the side opposite to the damage. The complaints are less severe than in peripheral palsy, because the paralysis affects only the facial muscles of the lower half of the face.

Paralysis of cranial nerves: vestibulocochlear nerve (VIII)

The eighth cranial nerve is associated with senses other than those mentioned so far - because it perceives auditory stimuli, it is also related to the sense of balance. The paralysis of the vestibulocochlear nerve can result in tinnitus, but also in progressive (even up to complete) hearing loss. Patients may also experience dizziness and problems with balancing.

Paralysis of cranial nerves: glossopharyngeal (IX) nerve

The glossopharyngeal nerve is involved, inter alia, in in the perception of taste stimuli, it also controls the activity of the throat muscles. In addition to these, this nerve has fibers that control the function of the salivary and lacrimal glands. The paralysis of the ninth cranial nerve leads to a loss of taste sensation in the rear third of the tongue, and may also lead to sensory disturbances in the soft palate. Swallowing disorders can also be a problem with paralysis of this nerve.

Paralysis of cranial nerves: vagus nerve (X)

The tenth cranial nerve controls the motor activity of the laryngeal and pharyngeal muscles, and is also responsible for the reception of sensory stimuli from many parts of the body - the vagus nerve fibers receive sensory signals from both the neck organs and those located in the abdominal cavity. Paralysis of the vagus nerve causes disordersarticulation of speech, in addition to them, a drop of the soft palate may be observed in patients. When examining the oral cavity of a patient with vagus nerve palsy, the uvula may deviate to the opposite side of the lesion. The gag reflex (commonly known as the gag reflex) may also disappear.

Paralysis of cranial nerves: accessory nerve (XI)

The main function of the ninth cranial nerve is to govern the motor activity of the sternoclavicular and trapezius muscles. Paralysis of the accessory nerve causes the shoulder to drop, and it may be difficult to move the head in the opposite direction to the nerve injury.

Paralysis of cranial nerves: sublingual (XII) nerve

The twelfth cranial nerve is primarily responsible for the locomotor activity of the tongue. In the case of paralysis of the sublingual nerve, when the tongue is extended, it deviates towards the damage, in addition, patients may develop a slight disturbance of the articulation of speech.

Particular forms of cranial nerve dysfunction

The symptoms of paralysis of single cranial nerves are described above. However, there are many conditions that result from paralysis of several nerves at the same time, thanks to which the patient develops much more ailments. Examples of disorders in which the function of several cranial nerves are disturbed simultaneously include:

  • superior orbital fissure syndrome (paralysis of III, IV and VI nerves with paralysis of one of the branches of the V nerve),
  • Tolosa-Hunt syndrome (nerve palsy III, IV, V and VI),
  • bulbar palsy (related to disorders of the IX, X and XII nerves),
  • pseudo-follicular paralysis (in which the V, VII, IX, X and XII nerves are paralyzed).

It is also worth mentioning the alternating trunks. They occur in the case of damage to specific centers in the brainstem, and are manifested in the paralysis of the cranial nerve on the same side and the occurrence - on the opposite side - of a motor deficit, which may be accompanied by sensory disturbances. Benedict's syndrome is an example of truncated alternating syndrome, where nerve III paralysis and paresis appear, patients may also experience involuntary movements.

Category:

Neurology