Lightheadedness and vertigo


 * Associate Editor-In-Chief:

Overview
Lightheadedness is a common and often unpleasant sensation of dizziness and/or feeling that one may be about to faint, which may be transient, recurrent, or occasionally chronic. In some cases, the individual may feel as though his or her head is weightless. It can be simply an indication of a temporary shortage of blood or oxygen to the brain, low blood pressure, low blood sugar, or anemia. It can also be a symptom of many other conditions, some of them serious, such as heart disease, stroke, or bleeding.

Vertigo, a specific type of dizziness, is a major symptom of a balance disorder. It is the sensation of spinning or swaying while the body is stationary with respect to the earth or surroundings. There are two types of vertigo: subjective and objective. Subjective vertigo is when a person feels a false sensation of movement. Objective vertigo is when the surroundings will appear to move past a person's field of vision.

The effects of vertigo may be slight. It can cause nausea and vomiting and, if severe, may give rise to difficulty with standing and walking.

The word "vertigo" comes from the Latin "vertere", to turn + the suffix "-igo", a condition = a condition of turning about.

Pathophysiology of vertigo
Vertigo is usually associated with a problem in the inner ear balance mechanisms (vestibular system), in the brain, or with the nerve connections between these two organs.

The most common cause of vertigo is benign paroxysmal positional vertigo, or BPPV. Vertigo can be a symptom of an inner ear infection. Vertigo can be a symptom of an underlying harmless cause, such as in BPPV or it can suggest more serious problems. These include drug toxicities (specifically gentamicin), strokes or tumors (though these are much less common than BPPV), syphilis.

Vertigo can also be brought on suddenly through various actions or incidents, such as skull fractures or brain trauma, sudden changes of blood pressure, or as a symptom of motion sickness while sailing, riding amusement rides, airplanes or in a motor vehicle. Vertigo can also be caused by Carbon Monoxide poisoning. It is also one of the more common symptoms of superior canal dehiscence syndrome and Meniere's Disease.

Vertigo-like symptoms may also appear as paraneoplastic syndrome (PNS) in the form of opsoclonus myoclonus syndrome, a multi-faceted neurological disorder associated with many forms of incipient cancer lesions or virus. If conventional therapies fail, consult with a neuro-oncologist familiar with PNS.

Classification
Vertigo is typically classified into one of two categories depending on the location of the damaged vestibular pathway. These are peripheral or central vertigo. Each category has a distinct set of characteristics and associated findings.

Vertigo can also occur after long flights or boat journeys where the mind gets used to turbulence, resulting in a person feeling as if they are moving up and down. This usually subsides after a few days.

Neurochemistry of vertigo
The neurochemistry of vertigo includes 6 primary neurotransmitters that have been identified between the 3-neuron arc that drives the vestibulo-ocular reflex (VOR). Many others play more minor roles.

Three neurotransmitters that work peripherally and centrally include glutamate, acetylcholine, and GABA.

Glutamate maintains the resting discharge of the central vestibular neurons, and may modulate synaptic transmission in all 3 neurons of the VOR arc. Acetylcholine appears to function as an excitatory neurotransmitter in both the peripheral and central synapses. GABA is thought to be inhibitory for the commissures of the medial vestibular nucleus, the connections between the cerebellar Purkinje cells and the lateral vestibular nucleus, and the vertical VOR.

Three other neurotransmitters work centrally. Dopamine may accelerate vestibular compensation. Norepinephrine modulates the intensity of central reactions to vestibular stimulation and facilitates compensation. Histamine is present only centrally, but its role is unclear. It is known that centrally acting antihistamines modulate the symptoms of motion sickness.

The neurochemistry of emesis overlaps with the neurochemistry of motion sickness and vertigo. Acetylcholine, histamine, and dopamine are excitatory neurotransmitters, working centrally on the control of emesis. GABA inhibits central emesis reflexes. Serotonin is involved in central and peripheral control of emesis but has little influence on vertigo and motion sickness.

Differential Diagnosis
In alphabetical order
 * Acoustic neuroma
 * Acute cochleo-vestibular dysfunction
 * Acute labyrinthitis
 * Aging
 * Alcoholism
 * Anemia
 * Anticonvulsants
 * Antihypertensives
 * Anxiety
 * Aortic stenosis
 * Arrhythmia
 * Arteriosclerosis
 * Atrial Fibrillation
 * Aura of epileptic attack
 * Autoimmune disease
 * Autoimmune inner ear disease
 * Bacterial labyrinthitis
 * Basil meningitis
 * Basilar migraine
 * Benign paroxysmal positional vertigo
 * Brain stem injury
 * Car sickness
 * Cardiac dysrhythmia
 * Cardiac valve stenosis
 * Carotid sinus pressure
 * Cerebrovascular accident (CVA)
 * Cervical spondylosis
 * Cervicogenic vertigo
 * Cholesteatoma
 * Chronic otitis media
 * Circulation-caused vertigo
 * Congestive Heart Failure (CHF)
 * Dehydration
 * Diabetes Mellitus
 * Diuretics
 * Drugs, toxins
 * Ependymoma
 * Epidemic vertigo
 * Epilepsy
 * Friedrich's Ataxia
 * Heart failure
 * Height vertigo
 * Hyperglobulia
 * Hypertension
 * Hypertrophic cardiomyopathy
 * Hyperventilation
 * Hypotension
 * Hypoxia
 * Hypoxemia
 * Inflammation
 * Intoxications
 * Kinetosis
 * Labyrinth apoplexy
 * Labyrinthine concussion
 * Labyrinthine trauma]]
 * Labyrinthitis
 * Lateral medullary syndrome
 * Mastoiditis
 * Measles
 * Meniere's Disease
 * Metabolic disorders
 * Metastasis
 * Migraine
 * Multiple Sclerosis
 * Neuritis vestibularis
 * Ocular vertigo
 * Otitis externa
 * Ototoxic drugs
 * Perilymphatic fistula
 * Phobic vertigo
 * Postural hypotension
 * Psychogenic
 * Sedatives
 * Serous labyrinthitis
 * Serous otitis
 * Seizure
 * Shy-Drager Syndrome
 * Spondylosis cervicalis
 * Subclavian-Steal Syndrome
 * Syncope
 * Syphilis
 * Syringobulbia
 * Tabes dorsalis
 * Temporal bone fracture
 * Tertiary syphilis
 * Transient ischemic attack (TIA)
 * Tumor
 * Typhoid Fever
 * Uremia
 * Vasovagal response
 * Vertebro-basilar insufficiency and thromboembolism
 * Vestibular neuronitis
 * Vigilance impairment
 * Viral labyrinthitis
 * Vitamin B12 Deficiency
 * Visual deficit
 * Von Hippel-Lindau Syndrome
 * Wallenberg's Syndrome

Characteristics of Vertigo

 * Vertigo is characterized by spatial disorientation
 * The most common cause of vertigo is an underlying inner ear pathology
 * True vertigo is experienced as a tilting or sloping of the environment
 * Characteristics of vertigo:
 * Ataxia
 * Nausea
 * Nystagmus
 * Vomiting

Diagnosis
Tests of vestibular system (balance) function include electronystagmography (ENG), rotation tests, Caloric reflex test, and Computerized Dynamic Posturography (CDP). Tests of auditory system (hearing) function include pure-tone audiometry, speech audiometry, acoustic-reflex, electrocochleography (ECoG), otoacoustic emissions (OAE), and auditory brainstem response test (ABR; also known as BER, BSER, or BAER). Other diagnostic tests include magnetic resonance imaging (MRI) and computerized axial tomography (CAT, or CT).

History and Symptoms

 * Signs of dehydration
 * History of heart disease
 * Excessive pressure on neck
 * Headaches
 * Cardiac auscultation
 * Hearing loss
 * Neurologic exams
 * Complete ears, nose, throat (ENT) exam
 * Blood pressure

Laboratory Findings

 * Calcium
 * Glucose
 * Complete blood count (CBC)
 * Erythrocyte sedimentation rate (ESR)
 * Blood urea nitrogen (BUN)/creatinine
 * B-type natriuretic peptide (BNP)
 * Stool occult blood testing
 * Arterial blood gases
 * Carbon monoxide level]
 * Pulse oximetry
 * Eosinophil count

Electrolyte and Biomarker Studies

 * Electrolytes

Electrocardiogram

 * ECG and 24-hour ECG monitoring may be indicated

MRI and CT

 * CT scan and MRI of head and or labyrinth may be necessary

Echocardiography or Ultrasound

 * Echocardiogram may be indicated

Other Imaging Findings

 * Electronystagmography may be indicated
 * Electroencephalogram (EEG) may also be indicated

Other Diagnostic Studies

 * Carotid doppler (presence of TIAs)
 * Dix-Hallpike maneuver
 * Barany maneuver (less specific than Dix-Hallpike)
 * Evaluation of hearing

Treatment

 * Reassurance and time important for treatment of vertigo
 * Specific treatment required for central causes
 * Vestibular rehabilitation
 * anticholinergics
 * antihistamines
 * benzodiazepines
 * calcium channel antagonists, specifically Verapamil and Nimodipine
 * GABA modulators, specifically gabapentin and baclofen
 * Neurotransmitter reuptake inhibitors such as SSRI's, SNRI's and Tricyclics

Treatment for lightheadedness can include drinking plenty of water or other fluids (unless the lightheadedness is the result of water intoxication in which case drinking water is quite dangerous), eating something sugary, and lying down or sitting and reducing the elevation of the head relative to the body (for example by positioning the head between the knees).

Acute Pharmacotherapies

 * Meclizine
 * Diuretics for Meniere's Disease

Surgery and Device Based Therapy

 * For positional symptoms, repositioning maneuvers or a modified Epley is suggested
 * Patients with Meniere's Disease may require surgery