The brain stem serves as a “highway” that connects the rest of the brain to the spinal cord and through the spinal cord, to the rest of the body. The brain stem helps regulate breathing, digestion, heart function, sexual function and physical growth. Multiple sclerosis, or MS, is a disease that affects the brain and spinal cord by damaging the myelin that protects nerve cells and as a result, messages from brain to body can be impeded or completely blocked, which causes the symptoms of MS, notes Medline Plus. When MS results in lesions or damage, to the brain stem, a variety of symptoms can manifest.
Diplopia
Diplopia, or double vision, is caused by MS lesions in the brain stem, where the nerves that innervate the eye muscles are located, according to All About Multiple Sclerosis. Sixth nerve palsy, or abducens nerve palsy, is the most common cause of MS double vision, and because it affects the eye muscles that move the eye from side to side, double vision occurs when looking to the side, normally just to one side and not the other, notes All About Multiple Sclerosis. The sixth cranial nerve is located on a part of the brain stem called the pons, which is a favored site for MS lesions to occur, explains All About Multiple Sclerosis.
Vertigo
Vertigo is a dizzy sensation where the world spins uncontrollably, and is often accompanied by nausea and vomiting. In MS, vertigo is often accompanied by a loss of balance, and is most severe when a person has her eyes closed, explains All About Multiple Sclerosis, and is, therefore, often worse when lying in bed at night. It is caused by damage to the pons where the acoustic cranial nerve, or the eighth cranial nerve, is located, which is responsible for balance, notes All About Multiple Sclerosis. Severe vertigo in MS usually remits slowly over a few weeks and rarely persists long term; however, it often does result in a chronic dizzy sensation and a sensitivity to travel sickness.
Urinary Problems
Urinary problems like hesitancy of incontinence are also associated with MS lesions to the brain stem, notes All About Multiple Sclerosis. In particularly, the pons is a major relay center between the brain and the bladder. Urinary hesitancy is difficulty starting or maintaining a urinary stream, and it normally presents itself gradually and can go unnoticed until urinary retention, or the complete inability to urinate, results in bladder distension and discomfort, notes Medline Plus. Urinary incontinence is the loss of bladder control that can range from slight leaking to complete wetting.
Paralysis
Hemiplegia, paralysis of one side of the body, is another symptom of MS lesions on the brain stem, reports All About Multiple Sclerosis. Hemiplegia involves the arm, the leg, and, sometimes, the face of the affected side, which is usually opposite to the side with the brain lesion, notes MD Guidelines. Interestingly, lesions in the medulla, also part of the brain stem, can cause paralysis of other parts of the body, including "crossed paralyses," which refers to paralysis of the arm on one side of the body and the leg on the other, notes MD Guidelines, and are typical of brain stem lesions.
