What Are The Most Common CNS Disorders & What Are It’s Symptoms?
CNS refers to the central nervous system of the body and it consists of the brain and the spinal cord, which together control the major functions of the body. Any lesion caused in the brain and spinal cord can lead to some dangerous and deadly disorders. Some of these common CNS disorders and their symptoms are:
CNS Disorder #1: Seizures and Epilepsy
A seizure is one of the commonest CNS disorder and is described as a sudden event due to abnormal excessive or synchronous neuronal activity in the brain. Depending on the distribution of discharges, this abnormal brain activity can have various manifestations. About 5-10% of the population will have at least one seizure with the highest incidence occurring in early childhood and late adulthood. Dramatic convulsive activities occur leading to experiential phenomena not readily discernible by the observers.
CNS Disorder #2: Cerebrovascular Diseases & Their Symptoms
These include a group of CNS disorders which consist of: Small artery stroke, large vessels ischemia, carotid atherosclerosis, ischemic shock etc. Cerebrovascular diseases include some of the most common and devastating CNS disorders: ischemic stroke and hemorrhagic stroke. Stroke is the second leading cause of death worldwide. Strokes cause 200,000 deaths each year in the United States and are a major cause of disability.
Cerebral ischemia is caused by a reduction in blood flow that lasts longer than several seconds. Neurologic symptoms are manifested within seconds because neurons lack glycogen and so the energy failure is rapid. If the cessation, that is stoppage of flow, lasts for less than three minutes then tissue death occurs.
Symptoms of Stroke Include:
The most common small-vessel stroke syndromes are the following:
- Pure motor hemiparesis from an infarct in the posterior limb of the internal capsule or the pons; and face, arm, and leg are almost always involved;
- Pure sensory stroke from an infarct in the ventral thalamus;
- Ataxic hemiparesis from an infarct in the ventral pons or internal capsule;
- And dysarthria and a clumsy hand or arm due to infarction in the ventral pons or in the genu of the internal capsule.
Other Symptoms of Stroke include: Loss of consciousness, shock, cold and clammy skin, dehydration, general fatigue, weakness, lethargy and it can also be mortal.
Transient symptoms (small-vessel TIAs) may herald a small-vessel infarct; they may occur several times a day and last only a few minutes. Recovery from small-vessel strokes tends to be more rapid and complete than recovery from large-vessel strokes; in some cases. However, there is severe permanent disability.
A large-vessel source (either thrombosis or embolism) may manifest initially as a small-vessel infarction. Therefore, for embolic sources (carotid and heart) should not be completely abandoned in the evaluation of these patients. Secondary prevention of small-vessel stroke involves risk factor modification, specifically reduction in blood pressure.
CNS Disorder #3: Migraine
Migraine is the second most common cause of a headache and the most common headache-related and indeed the CNS cause of disability in the world. It afflicts approximately 15% of women and 6% of men over a year period.
A migraine can often be recognized by its activators referred to as triggers. The symptom of this CNS disorder is sensitivity to environmental and sensory stimuli; migraine-prone patients do not habituate easily to sensory stimuli. This sensitivity is amplified in females during the menstrual cycle.
Common Signs & Symptoms of Migraine Include: Nausea, photophobia, lightheadedness, scalp tenderness, vomiting, visual disturbances, parenthesis, vertigo, photopsia, alteration of consciousness, diarrhea, fortification spectra, syncope, seizure and confusion.
CNS Disorder #4: Alzheimer's Disease
Approximately 10% of all persons over the age of 70 years have significant memory loss and in more than half of them, the cause is the Alzheimer's disease, which is a CNS disorder. It is estimated that the median annual total cost of caring for a single patient with advanced Alzheimer's disease is >$50,000 while the emotional toll for family members and caregivers is immeasurable. Alzheimer's disease can manifest as young as in the third decade and it is the most common cause of dementia in the elderly.
Patients most often present with an insidious loss of episodic memory followed by a slowly progressive dementia that evolves over years. A typical amnestic brain imaging reveals atrophy that begins in the medial temporal lobes before spreading to lateral and medial parietal and temporal lobes and lateral frontal cortex. Microscopically, there are neuritic plaques containing amyloid beta Alzheimer's disease neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau filaments and Alzheimer's disease accumulation of in blood vessel walls in cortex and leptomeninges. The identification of causative mutations and susceptibility genes for Alzheimer's disease has provided a foundation for rapid progress in understanding the biological basis of the disorder.
Symptoms of Alzheimer's Disease Include:
The cognitive changes of Alzheimer's disease tend to follow a characteristic pattern beginning with:
- Memory impairment (it is not present in 20% of the cases as the patients are able to memorize things well) and progressing to language and visuospatial deficits.
- Upstream visual processing dysfunction (referred to as posterior cortical atrophy syndrome).
- In the early stages of typical amnestic Alzheimer's disease, the memory loss may go unrecognized or be ascribed to benign forgetfulness of ageing.
- New evidence suggests that partial and sometimes generalized seizures proclaim Alzheimer's disease and can occur even prior to dementia onset.
- Eventually, with AD, the cognitive problems begin to interfere with daily activities, such as keeping track of finances, following instructions on the job, driving, shopping and housekeeping.
- Some Alzheimer patients are unaware of these difficulties (anosognosia), but most remain acutely attuned to their deficits. Changes in the environment (travel, relocation, hospitalization) tend to destabilize the patient. Over time patients become lost on walks or while driving.
- Social graces, routine behavior and superficial conversation may be surprisingly intact, and even into the later stages of the illness.
- In the late stages, some Alzheimer patients remain ambulatory, wandering aimlessly. Loss of judgment and reasoning is inevitable. Delusions are common, usually simple, with common themes of theft, infidelity, or misidentification.
CNS Disorder #5: Parkinson's Disease & Other Related CNS Disorders
Parkinson's disease (PD) is the second commonest neurodegenerative disease, exceeded only by Alzheimer's disease. The cardinal clinical features of this CNS disorder were first described by the English physician James Parkinson in 1817. It is noteworthy that James Parkinson was a general physician who captured the essence of this CNS disorder based on a visual inspection of a mere handful of patients. It is estimated that approximately 1 million persons in the United States, 1 million in Western Europe and 5 million worldwide suffer from this disorder. Parkinson’s Disease affects men and women of all races all occupations and all countries. The mean age of onset of this CNS disorder is about 60 years. The frequency of Parkinson’s Disease increases with aging, but cases can be seen in patients in their 20s and even younger. Based on the aging of the population and projected demographics, it is estimated that the prevalence of this CNS disorder will dramatically increase in the next several decades.
Common Signs & Symptoms of Parkinson’s Disease Include:
- Cardinal Motor Features include: Bradykinesia, rest tremor, rigidity, gait disturbance or postural instability.
- Other Motor Features include: Micrographia, masked facies (hypomimia), reduced eye blinking, soft voice (hypophonia), dysphagia and freezing.
- Non-motor Features include: Anosmia, sensory disturbances (pain), mood disorders (e.g. depression), sleep disturbances (e.g. rbd), autonomic disturbances, orthostatic hypotension, gastrointestinal disturbances, genitourinary disturbances, sexual dysfunction, cognitive impairment and dementia.
CNS Disorder #6: Dystonia
Dystonia is a CNS disorder, which is characterized by sustained (> 100 ms) or repetitive involuntary muscle contractions frequently associated with twisting and abnormal postures.
Symptoms of dystonia can range from minor contractions in an individual muscle group to severe and disabling involvement of multiple muscle groups. The frequency is estimated to be 300000 cases in the United States, but is likely to be much higher because many cases are not recognized. Dystonia is often brought on by voluntary movements (action dystonia) and can extend to involve muscle groups and body regions not required for a given action (overflow). It can be aggravated by stress and fatigue and attenuated by relaxation and sensory tricks such as touching the affected body part (geste antagoniste). Dystonia can be classified according to age of onset (childhood vs adult), distribution (focal, multifocal, segmental or generalized), or etiology (primary or secondary).
CNS Disorder #7: Restless Legs Syndrome
Restless legs syndrome (RLS) is a CNS disorder that affects approximately 10% of the adult population (it is rare in Asians) and can cause significant morbidity in some. This CNS disorder was first described in the seventeenth century by an English physician (Thomas Willis), but has only recently been recognized as being a bonafide movement disorder.
The four core symptoms required for diagnosis of this CNS disorder are as follows:
- An urge to move the legs usually caused or accompanied by an unpleasant sensation in the legs; symptoms that begin or worsen with rest;
- Partial or complete relief by movement; and worsening during the evening or night.
- Symptoms most commonly begin in the legs, but can spread to or even begin in the upper limbs.
- The unpleasant sensation is often described as a creepy-crawly feeling，paresthesia， or burning. In about 80% of patients, RLS is associated with periodic leg movements (PLMs) during sleep and occasionally while awake. These involuntary movements are usually brief lasting no more than a few seconds and recur every 5-10 seconds. The restlessness and PLMs are a major cause of sleep disturbance in patients leading to poor-quality sleep and day time sleepiness.