Diseases That Affect The Cranial Nerves
The nerves that arise from the brain and which are involved in the functions of smell, vision, eye movements, taste, facial sensations and movements, hearing, swallowing and speaking, tongue and neck movements are called cranial nerves. There are twelve pairs of cranial nerves (one on either side of the body). The table (on the next page) describes the main functions of each cranial nerve. There are also several diseases that can affect cranial nerves and here are three of the most common ones.
1 TRIGEMINAL NEURALGIA (Related To The Trigeminal Nerve)
Trigeminal neuralgia (TN) is characterized by episodes of severe sharp and shooting pain over the face. It usually affects only one side of the face (however, both Sides of face get affected in about 10 per cent of patients). The disease can affect anyone, but it is more common after the age of 50 years. Children are usually not affected and it is slightly more common in females than males.
Patients suffering from TN usually complain of severe, sharp, shooting pain affecting one side of face. Pain is usually located in the middle and lower thirds of the face, and the upper one third is uncommonly affected. Pain may also occur in the lips. gums, teeth. eye, ear, forehead or cheeks. The pain is described as an electric-Shock like semitone.
However, the pain is of short duration, usually lasting only for a few seconds and never more than one-two minutes. The pan also recurs several times in a week and sometimes several times in a day. Patients are often normal in between the pain attaö(s. There may also be relative periods of improvement lasting for a few months. Nevertheless. facial pain gets aggravated by simple activities like brushing the teeth, washing the face, chewing food, shaving, and sometimes, by light breeze/ air from the fan or air conditioner.
The diagnosis can be made on the basis of clinical symptoms. MRI of brain may be required to exclude compression on the trigeminal move by a blood vessel or rarely, a tum, our Trigeminal neuralgia can be treated in most cases with medications such as carbamazepine. However, in so-TE cases. symptoms do not get better with tablets. So these patients can be treated with radiation therapy (radiofrequency ablation) or surgery.
2 OPTIC NEURITIS (Due To The Involvement Of The Optic Nerve)
Optic neuritis (ON) is by sudden painless loss or impairment Of vision in one eye is affected. however, in some casæ, both eyes be affected.
The cause of ON is supposed to be an inflammation of the optic nerve. resulting in damage to the myelin sheath. This process is called demyelination. The commonest demyelinating disease is multiple sclerosis (MS). Ttwetore. an attack of optic neuritis (ON) may suggest a beginning of multiple sclerosis (MS).
Investigations should include MRI of the brain and a detailed eye examination to help determine the future chance of occurrence of MS in the patient. Initial treatment consists of a five-day course of steroid injections, Those believed to have a high risk of developing MS are treated With long-term immunotherapy to prevent future relapses of the disease.
As cranial nerves are involved in many important functions, a systematic approach incorporating a careful history and examination can help with the correct diagnosis of the disease affecting these nerves
3 BELL’S PALSY (Related To The Facial Nerve)
Bell’S palsy refers to paralysis (weakness) of facial muscles, the cause of which is not known. In most cases, it is thought to be caused by a herpes virus infection, Paralysis affects one of the face in most patients. Bell’s palsy can affect people of any age group. inducing children, However, people with diabetes and pregnant women are more prone to this condition.
Patients suffering from Bell’s palsy present with a deviation of the angle of the mouth to one side, which starts all of a sudden, As a result, the taco deviates to one side while talking or smiling. In most patients. there is difficulty in dosing the eyes and watering of the eyes may occur. Patients also find it difficult to suck through a straw. blow a balloon or whistle. In some cases, taste is also impaired.
The diagnosis of Bell’s palsy can be made on basis of symptoms and Signs in most cases. A brain scan may be needed for sorry, to exclucÉ other causes of facial muscle paralysis such as brain stroke, turn our or Infection. The treatment of Bell’S palsy includes medicines (such as steroids and acyclovir) and physiotherapy Physiotherapy involves facial muscle exercises and electrical stimulation of the affected facial nerve. Most patients respond well to the treatment and about 75 per cent of people completely recover in a month’s time.
Conclusions
Cranial nerves are involved in many important functions. Diseases affecting these nerves can present with a variety of ot symptoms Therefore, a systematic approach incorporating a careful history and examination can help with the correct diagnosis, in most cases. And once diagnosed and promptly treated, patients make a fast and significant recovery.