Optic atrophy

Optic atrophy is the result of the fibres of optic nerve failing to transmit the visual information to the brain due to the damaged optic nerve which may result in problems with vision. Optic atrophy refers to the loss or damage of the fibres of the optic nerve. Optic nerve is responsible for carrying images from the eye to the brain. Optic atrophy presents itself with pale appearance of the optic nerve head at the back of the eye; hence this condition is also referred to as optic nerve head pallor. Although optic atrophy affects one eye, bilateral optic atrophy can also occur when the illness damages the nerves of the both eyes.

What causes optic atrophy ?

Optic atrophy is a serious eye disorder that is caused by a underlying disease or condition. Few of the diseases originating in the eye and the nervous system that lead to optic Atrophy are given below.

• Compression of the optic nerve.
  
• Glaucoma or high pressure within the eye.
  
• Infection
  
• Multiple sclerosis
  
• Inflammation of the optic nerve called optic neuritis.
  
• Interruption in blood circulation to the optic nerve in the form of decreased blood supply (ischemia) or oxygen supply (hypoxia).
  
• Tumors on the visual pathway
  
• Trauma
  
• Optic atrophy can even be inherited from parents.
  
• Nutritional deficiencies (especially B12), certain medications and exposure to certain toxins also lead to optic atrophy.
  

Symptoms of optic atrophy

If you face any of these symptoms seek medical attention immediately as any progression of optic atrophy leads to vision loss. Though the occurrence of these symptoms does not necessarily mean optic atrophy, it is always better to rule out this severe eye condition. Ophthalmologist will examine the eyes with an ophthalmoscope and the doctor may recommend few more tests, if he suspects optic atrophy. Tests such as tonometry, pupil light reflex, color vision and visual acuity are conducted.

• Blurred vision
  
• Poor visual function such as low clarity of vision or visual acuity.
  
• Distorted peripheral vision.
  
• Problems in color vision
  
• Decreased brightness in the affected eye. Diminished reaction of the pupil to the light.
  
• Change in the optic disc

Treatment of optic atrophy

Currently there is no sure shot and effective treatment or therapy available for optic atrophy. However ophthalmologist diagnose the underlying condition or disorder that is causing optic atrophy and treat them. This will avoid the further damage of the optic nerve and preserve the existing vision.

Werdnig Hoffmann Disease

Spinal Muscular Atrophy or Werdnig-Hoffmann disease is also called as SMA1 or spinal muscular atrophy 1. This condition is inherited in an autosomal recessive manner. Degeneration of the nerve cells in the lowest region of the brain and degeneration of specific motor neurons (nerve cells that transmit nerve impulses from brain or spinal cord to the muscles) in the spine lead to muscle weakness. Slowly chewing and breathing also become a challenge. The lower limbs are generally weaker when compared to the upper limbs. These motor neurons are associated with activities such as crawling, walking, sitting up and controlling head movement.

As this condition leads to muscle weakness, kids born with this syndrome are unable to sit up without external support. Amongst the different types of spinal muscular atrophy, Werdnig-Hoffmann disease is the most severe. SMA1 is classified into 3 subgroups depending on the clinical signs and the period of onset.

Type I: Severe weakness since birth, head control is never achieved. Such children are mostly unable to support their head or sit unassisted. Choking and gagging occurs while breathing and swallowing.

Type II: Onset of weakness within 2 months from birth, head control is not achieved.

Type III: Onset of weakness after neonatal period however head control is achieved. A few children may be able to sit up with the help of external support.

Type IV: This type of spinal muscular atrophy occurs after the age of 30. There might be muscle weakness and tremors. In most cases, only the proximal muscles or those closest to the center of the body are affected. There might be involuntary muscle contractions, limb cramps and protrusion of abdomen.

There is no cure for Werdnig-Hoffmann disease and it is a fatal type disorder. The management of this condition could include support from speech therapy, occupational therapy, physiotherapy, palliative medical care and respiratory medicine.

Multiple System Atrophy

Multiple system atrophy (MSA) is an alarming neurological disease that can cause adverse effects on the body. The primary targets for this condition are the involuntary muscles. MSA is a rare form of neurological disorder. It damages the control and co-ordination of muscle related physiology. This degenerative disease has no underlying etiology. The damage is predominantly in the striatonigral and olivopontocerebellar regions of the brain.

This disease was also known as Shy Drager syndrome. Due to its association with Parkinsons-like symptoms and also partly with amyotrophic lateral sclerosis (ALS), it has been categorized as Multiple System Atrophy to specify the symptoms. This has enabled medical centers to evaluate and diagnose the disorder in an effective manner. Studies indicate that the populations that are affected by the MSA are often elderly groups.

Classification and clinical manifestations

Multiple system atrophy is classified into two types for definitive diagnosis during the evaluation of the patient based on the symptoms.

The Parkinsonian category: In this form of MSA, the symptoms associated are very closely related to the Parkinson's pattern. It is also called MSA-P. Muscle rigidity is observed along with slow movements of the muscles, which are also referred to as Bradykinesia. Muscle cell degeneration predominantly occurs in the striatonigral region leading to tremors, lack of balance and postural impairment.

Cerebellar category: This form of MSA is called MSA-C, which is associated with the ataxia of cerebellar region. Loss of balance and prominent gait are the noticeable symptoms. The onset of dysarthria affects the vocal muscles and the patient's voice slows down and sometimes becomes inaudible. This is followed by difficulty in swallowing as the muscles lose their control sustenance from the cerebral region. In addition to this, blurred vision and dizziness have been reported in MSA-C.

Other associated symptoms of Multiple System Atrophy are urinary incontinence, orthostatic hypotension, erectile dysfunction, urinary retention, constipation and uncontrolled bowel movements. Patients experience light-headedness, dizziness and also low blood pressure because of the slow responses associated with the autonomic nervous system. The reflex arc and its respective functions are also impaired especially in Parkinsonian category.

Autonomic function tests are done to detect the onset of MSA-P and MSA-C at an earlier stage. Research affirms that although MSA is a rare form of neurological disorders, the occurrence in elderly people is slowly increasing. This is because of the lifestyle patterns and also underlying medical conditions such as diabetic neuropathy and Alzheimer's. Statistics indicate that the MSA occurs in 4 in every 100,000 people.

In most cases, diagnosis is done through a complete study of the muscle physiology and skeletal muscle responses after a certain age. In males, prostrate related carcinomas and myelomas can also aggregate this disorder in a larger way as it deteriorates the muscle tissue causing abnormal rise of non-functional proteins in the body.

Diagnosis and Treatment

MSA is diagnosed by evaluating the history of the patient and through physical examination. Tests such as muscle extension, flexion, and response to stimuli, vocal tone strength and posture are done to evaluate the muscle dexterity and functionality. Laboratory diagnosis of blood samples are done to evaluate liver and kidney function tests. In men prostrate examination is also done to study the urological coherence to the respective disease. Urology tests such as uroflowmetry and urinary control is investigated to study the extent of atomic nervous system and cerebellar functionality. Cardiac evaluations are performed to study hypotension and arrhythmia associated with it. Radiological examinations such as CT, PET and MRI are done to understand the involvement of central nervous control damage.

Therapeutic treatments are most often used with MSA. In many cases physical, occupational and speech therapies are done to increase the muscle movements and response of the patient. For Parkinsonian related MSA, L-Dopa, amantadines are administered for better results. Other drugs include Fludrocortisone, Midodrine, Oxybutinin, and Trospium chloride and botulinum toxin incase of dystonia.