Cranial Nerve Damage from Head Trauma (2024)

The cranial nerves are vulnerable to damage during head trauma. Many of them run over the surface of the skull, protected only by the muscles and tissues of the face. Head trauma occurs when there is an injury to the scalp, skull, or brain, like if you have a scalp wound or skull fracture.

Even mild head trauma like a concussion can cause cranial nerve damage. The symptoms may appear immediately following the trauma, or they may not appear until days or weeks after the incident. The effects of cranial nerve injury may be temporary or permanent, depending on the nature of the injury.

This article covers the functions of the 12 cranial nerves and the symptoms you may see if one or more of these nerves are damaged. It also explains how cranial nerve damage is diagnosed and treated, and what to expect if you or someone you know has cranial nerve damage.

Cranial Nerve Damage from Head Trauma (1)

Cranial Nerve Functions

There are a total of 12 cranial nerves. These nerves exit from the base of the brain and run through different parts of the face and head. The cranial nerves perform essential functions from providing sensation and controlling facial movements to initiating protective reflexes.

Since the cranial nerves control observable activities such as moving the eyes, chewing, and smiling, damage can be seen and felt when the nerve’s associated function is altered. Here is what the 12 cranial nerves do:

  • CN I—Olfactory: provides the sense of smell
  • CN II—Optic: communicates visual information from the eye to the brain
  • CN III—Oculomotor: controls numerous movements of the eyes and the eyelids; also controls the size of the pupils in response to light
  • CN IV—Trochlear: controls the movement of the eyes downward and inward toward the nose
  • CN V—Trigeminal: communicates the sensation of touch to the face; also controls the chewing muscles
  • CN VI—Abducens: controls the horizontal movement of the eyeball
  • CN VII—Facial: moves the muscles that create facial expressions; provides the sense of taste to the front two-thirds of the tongue
  • CN VIII—Vestibulocochlear: provides the sense of hearing, communicates information about the body’s position in space to the brain
  • CN IX—Glossopharyngeal: controls throat muscles and salivary glands; provides taste information from the back third of the tongue; senses changes in blood pressure and communicates that to the brain so it can respond
  • CN X—Vagus: controls the heart, lungs, and abdominal organs
  • CN XI—Spinal Accessory: controls throat and neck muscles
  • CN XII—Hypoglossal: moves the tongue and enables speech

These nerves control essential functions of the head, face, neck, and more. While sometimes the damage is noticeable right away, it can also take hours to days for a disability to manifest. For example, if there is a growing blood clot pressing on a cranial nerve and the nerve begins to die, this can take some time to show up.

Symptoms of Cranial Nerve Damage

Different types of cranial nerve damage will cause different symptoms depending on which nerves are damaged. General symptoms of nerve damage include:

  • Pain
  • Tingling sensation
  • Numbness
  • Abnormal smell or taste
  • Skin that feels sensitive to touch
  • Ringing in the ears (tinnitus)
  • Weak or paralyzed muscles, which may result in drooling, choking, or slurred speech
  • Vision changes and double vision

Damage to specific cranial nerves can produce specific types of symptoms:

  • Nose—CN I: One of the most common causes of damage to the olfactory nerve is a traumatic brain injury. Damage to this nerve not only affects the sense of smell but also the ability to taste food since smell is an important component of taste.
  • Vision—CN II: Damage to the optic nerve can cause several visual impairments, depending on the location of the injury. Vision loss can affect one or both eyes.
  • Eye movements—CN III, IV, and VI: These three cranial nerves control the eyes. Damage to the oculomotor nerve (CN III) can cause a droopy eyelid, changes in the pupil's response to light, and abnormalities in eye movements (up and down, and side to side). Trochlear nerve (CN IV) injury can result in double vision and involuntary (uncontrolled) eye movement (nystagmus).
  • Forehead, cheeks, jaw—CN V: Trigeminal nerve damage can affect motor and sensory function in your forehead, cheeks, and jaw. It can also affect teeth clenching and blinking.
  • Facial motor and sensory dysfunction—CN VII: If the facial nerve is damaged, one side of the face will not be able to make expressions, and lips may not move normally. A droop in the eyebrows, mouth, or both may be seen. Taste may be altered as well. Damage to this nerve is distressing because it impairs one of our most relied upon forms of expression, and also affects one’s self-image.
  • Hearing and balance—CN VIII: Damage to the vestibulocochlear, or acoustic, nerve can affect your sense of hearing, as well as your balance, causing dizziness or difficulty walking, sitting, or standing. This can increase your risk of falls.
  • Swallowing—CN IX and X: Your ability to swallow and your gag reflex may be affected if your glossopharyngeal and vagus nerves are injured. Hoarseness is another symptom of damage to these nerves.
  • Shoulders and head—CN XI: If your spinal accessory nerve is damaged, you may have difficulty shrugging your shoulders and turning your head to the side.
  • Tongue—CN XII: Damage to the hypoglossal nerve may cause problems with your ability to control tongue movements.

How Is Cranial Nerve Damage Diagnosed?

Depending on the extent of the injury, healthcare providers may test the cranial nerves as part of a neurological exam, or they may perform specific tests to check the function of individual cranial nerves that may be injured.

To test for sensory and motor function of the cranial nerves, your healthcare provider may ask you to follow a finger with your eyes, say "ah," and stick your tongue out. The provider may also touch certain parts of your face, use a tuning fork, assess your pupillary response to light, and perform other tests.

If necessary, an MRI may be ordered because it can visualize the fine details of the nerves. A CT may be necessary if damage to the structure around the nerves is suspected.

Treatment for Cranial Nerve Damage

If a cranial nerve is completely cut in two, it cannot be repaired. However, if it is stretched or bruised but remains intact, the nerve can recover. This takes time and can cause a variety of unpleasant symptoms including tingling and pain. These symptoms are a good sign that the nerve is healing.

Steroids may be used to decrease inflammation around a cranial nerve. Surgery is sometimes needed if a collection of blood, called a hematoma, is squeezing the nerve and leading to paralysis or dysfunction.

Neurologists and neurosurgeons have specialized assessments and interventions that address this type of nerve damage and should be consulted.

Outlook for Cranial Nerve Damage

Cranial nerve damage may cause partial or complete dysfunction, and the symptoms may be temporary or permanent.

One study looking at cranial nerve damage in patients with traumatic brain injury found that recovery tended to be seen more often among the participants in the younger age group and in people with delayed symptoms.

Nerve damage can be disabling and may require rehabilitation. The nerves that control eye movement and facial expressions may have a greater chance of regaining function than the olfactory, optic, and vestibulocochlear nerves.

Summary

The cranial nerves can be damaged from mild head injuries like concussions or more major injuries like fractures. Symptoms of cranial nerve damage can include pain, abnormal sensations, changes in vision, and weak or paralyzed muscles. They may show up immediately after the incident or may not appear until days or weeks later.

Talk to a healthcare provider immediately if you notice signs or symptoms of cranial nerve damage following head trauma. Treatment is available and, in some cases, the damage can be completely reversed, allowing you to make a full recovery.

8 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. MedlinePlus. Head injury - first aid.

  2. Basheer N, Varghese JC, Kuruvilla R, Alappat JP, Mathew J. A prospective study on the incidence and outcome of cranial nerve injuries in patients with traumatic brain injuries. Indian J Neurotrauma. 2021;18:45-50. doi:10.1055/s-0041-1724141

  3. University of Rochester Medical Center. Cranial neuropathies.

  4. Limphaibool N, Iwanowski P, Kozubski W, et al. Subjective and objective assessments of post-traumatic olfactory dysfunction. Front Neurol. 2020;11:970. doi:10.3389/fneur.2020.00970

  5. American Nurses Association. Use mnemonics to aid remembering and identifying abnormal findings.

  6. Romano N, Federici M, Castaldi A. Imaging of cranial nerves: a pictorial overview. Insights Imaging. 2019;10:33. doi:10.1186/s13244-019-0719-5

  7. NYU Langone Health. Medication for facial nerve paralysis.

  8. Huckhagel T, Riedel C, Rohde V, Lefering R. Cranial nerve injuries in patients with moderate to severe head trauma - Analysis of 91,196 patients from the TraumaRegister DGU® between 2008 and 2017. Clin Neurol Neurosurg. 2022;212:107089. doi:10.1016/j.clineuro.2021.107089

By Eva Hvingelby, NP, PhD
Eva Hvingelby NP, PhD, is a nurse practitioner, researcher, educator, and health consultant specializing in trauma.

See Our Editorial Process

Meet Our Medical Expert Board

Was this page helpful?

Thanks for your feedback!

What is your feedback?

Cranial Nerve Damage from Head Trauma (2024)

FAQs

Cranial Nerve Damage from Head Trauma? ›

Damage to specific cranial nerves can produce specific types of symptoms: Nose—CN I: One of the most common causes of damage to the olfactory nerve is a traumatic brain injury. 4 Damage to this nerve not only affects the sense of smell but also the ability to taste food since smell is an important component of taste.

What is the most common cranial nerve injury in head trauma? ›

The most affected CN was the olfactory nerve (CN I), followed by the facial nerve (CN VII) and the oculomotor nerves (CNs III, IV, and VI). When more than 1 CN was involved, the most frequent association was between CNs VII and VIII.

What are the symptoms of cranial nerve trauma? ›

Individuals with a cranial nerve disorder may suffer from symptoms that include intense pain, vertigo, hearing loss, weakness or paralysis. These disorders can also affect smell, taste, facial expression, speech, swallowing, and muscles of the neck.

Can you recover from cranial nerve damage? ›

Many types of cranial neuropathies will get better with time, without any treatment. Sometimes medicines can be used to treat an infection, help reduce swelling in or near a nerve, or help if the neuropathy is causing pain. For some types of neuropathies and in some cases, surgery may help.

Is cranial nerve damage brain damage? ›

Cranial neuropathies are caused by damage to one or more cranial nerves. These are nerves that arise directly from the brain. They affect movement and feeling in the eyes and face.

How long does it take for a cranial nerve to heal? ›

Treatment outcomes of cranial nerve injuries are most commonly assessed on a functional basis. Most cranial nerve deficits have been found to improve over the course of a few months to a year.

How serious is nerve damage in head? ›

Cranial nerve damage may result in: Paralysis of facial muscles or losing sensation in the face. Loss of or altered sense of smell or taste. Loss of vision or double vision.

How do you test for cranial nerve damage? ›

The oculomotor, trochlear, and abducens nerves are tested by holding a pen or finger 30 to 40 cm in front of the patient and moving in an H-shaped pattern pausing during vertical and lateral gaze. [1] The patient should follow the target with their eyes, carefully keeping their head still.

Can cranial nerves repair themselves? ›

If a cranial nerve is completely cut in two, it cannot be repaired. However, if it is stretched or bruised but remains intact, the nerve can recover. This takes time and can cause a variety of unpleasant symptoms including tingling and pain. These symptoms are a good sign that the nerve is healing.

How do you know if you have nerve damage in your brain? ›

Without properly functioning nerves, you are likely to experience uncomfortable or even painful sensations. These occur because the nerves are not able to carry the correct signals from the brain to the spinal cord. The signs of nerve damage include the following: Numbness or tingling in the hands and feet.

How long does it take for a nerve damage in the head to heal? ›

Regeneration time depends on how seriously your nerve was injured and the type of injury that you sustained. If your nerve is bruised or traumatized but is not cut, it should recover over 6-12 weeks. A nerve that is cut will grow at 1mm per day, after about a 4 week period of 'rest' following your injury.

At what point is nerve damage permanent? ›

But it's also important to know there's often a ticking clock with nerve injuries. When a patient loses mobility in an arm or leg, you often can't get nerve function back if you wait too long. After 12 to 18 months, the connection between the nerve and muscle dies off and can no longer be restored.

What are the first signs of nerve damage? ›

The most common symptoms of a nerve condition include: A feeling of numbness, pain, tingling, or burning in your limbs or extremities. Unexplained weakness, loss of muscle strength, or paralysis. A headache that is persistent, comes on suddenly, or is "different"

What is the most commonly affected cranial nerve in traumatic brain injury? ›

CONCLUSION: The incidence of cranial nerves injury following acute head injury is significant (17.6%). The most common mode of trauma was due to RTA. The facial and abducent nerves are the most commonly affected cranial nerves. The trigeminal and lower four cranial nerves are very rarely affected.

Can MRI show cranial nerve damage? ›

Cranial nerve dysfunctions may be the result of pathological processes of the cranial nerve itself or be related to tumors, inflammation, infectious processes, or traumatic injuries of adjacent structures. Magnetic resonance imaging (MRI) is considered the gold standard in the study of the cranial nerves.

Can nerve damage in brain heal? ›

In most parts of your brain, the set of neurons you're born with is what you've got for life — just like your fingers and toes, if you lose any, they're not coming back. The body does have ways to encourage healing after a brain injury, but they are extremely constrained.

Which cranial nerve is most susceptible to trauma? ›

Cranial Nerve IV

CN IV is the most vulnerable to trauma of all the CNs, due to its long course and thin, fragile configuration. Even mild injuries to the head may cause traumatic CN IV palsy, in contrast with CN III and CN VI nerve palsies that usually require a stronger force of impact.

Which cranial nerve is most commonly damaged? ›

In general, cranial nerves I through VII are most frequently injured. Blunt trauma is associated with injury of the olfactory, facial, and vestibulocochlear nerves. Penetrating orbital trauma or fractures through the optic canal may result in optic nerve injury.

What is the most vulnerable cranial nerve? ›

The sixth nerve is especially vulnerable to increased intracranial pressure (ICP) due to its positioning between the brainstem and clivus in the subarachnoid space (Figure 3). Figure 3. Course of the sixth cranial nerve.

What happens if cranial nerve 4 is damaged? ›

Inability to move the eye down and in toward the nose. Double vision (because the two eyes are not pointed in the same direction). This double vision is vertical and torsional (tilted) Tilting of the head to compensate for the double vision.

References

Top Articles
Latest Posts
Article information

Author: Geoffrey Lueilwitz

Last Updated:

Views: 6105

Rating: 5 / 5 (80 voted)

Reviews: 87% of readers found this page helpful

Author information

Name: Geoffrey Lueilwitz

Birthday: 1997-03-23

Address: 74183 Thomas Course, Port Micheal, OK 55446-1529

Phone: +13408645881558

Job: Global Representative

Hobby: Sailing, Vehicle restoration, Rowing, Ghost hunting, Scrapbooking, Rugby, Board sports

Introduction: My name is Geoffrey Lueilwitz, I am a zealous, encouraging, sparkling, enchanting, graceful, faithful, nice person who loves writing and wants to share my knowledge and understanding with you.