In 1861, eminent French physician Paul Broca discovered the part of the brain that is responsible for speech production. Aptly named Broca’s area, the part of the brain Broca studied came from a patient known as “Tan,” who suffered from aphasia. Tan was unable to produce any meaningful speech by the end of his life, when the only recorded phrase he said to Paul Broca was “tan,” hence his name. Following the death of Tan, Paul Broca examined the aphasics brain and discovered that there was significant damage sustained to the left hemisphere, specifically in Broca’s area. This lead to the eventual characterization of the condition the patient Tan suffered from as Broca’s aphasia .
Overview and Symptoms
Broca’s aphasia is a language disorder characterized by the inability to produce meaningful speech and written language. As Broca’s aphasia is a non-fluent (expressive) aphasia, affected patients are able to understand heard speech, but cannot produce speech or write meaningful language. This pathology is the opposite of what happens in Wernicke’s aphasia (the fluent form of aphasia in which language comprehension is disrupted). The severity of failing to comprehend heard speech varies from a patient to another, although generally an aphasic can comprehend more than 50% of heard words. Besides the loss of meaningful speech production, the physical manifestations of the condition most commonly include patterns of speaking in incoherent, incomplete and short sentences; producing unrecognizable words; failing to understand conversations; and constructing sentences that lack logic .
Typically, Broca’s aphasia is caused by a stroke. Nearly 40% of all stroke patients will experience some form of aphasia after suffering from the incident, and Broca's aphasia accounts for about 12% of those cases . Other relatively common causes of Broca’s aphasia include sustained brain trauma, tumors, cerebral hemorrhages (a type of stroke that results in bleeding due to ruptured blood vessels), and extradural hematoma (brain injury caused by blood buildup). Neurological conditions such as Alzheimer's Disease and epilepsy can produce aphasia in some instances as well.
Broca’s aphasia, or more commonly referred to simply as Broca’s area, is the result of damage in the inferior frontal gyrus. When an injurious event such as a stroke or a tumor develops, the natural function of the brain region is altered, disrupting typical speech and language abilities. The degree to which a patient regains their language abilities is largely dependent upon activation of brain tissue surrounding the area that was damaged. Blood flow to damaged areas is also crucial for proper neuron recovery in such areas.
Figure 1: Image of Broca’s area in the left frontal lobe of the cerebrum .
The methods used to reach a proper diagnosis of Broca’s aphasia vary from patient to patient. Typically, doctors will perform several tests such as the Boston Diagnostic Aphasia Examination (BDAE) and the Western Aphasia Battery (WAP) in order to determine whether or not the symptoms a patient experiences are the result of aphasia. The BDAE tests language abilities through analysis of responses to visual and auditory stimuli. The WAP investigates the degree to which a patient is suffering from aphasia and can be used to classify what type they have. Additionally, physicians may use other diagnostic tools such as MRI scans or assessing the ability of the patient to identify objects and carry out normal conversations without significant difficulty . Dysphagia -trouble swallowing - may also be useful in diagnosing Broca’s aphasia, as it is used as a means to rule out expressive aphasia because throat impairment often results in difficulty with speech production. The Porch Index of Speech Ability can also be employed to further test the categorization of the suspected aphasia.
While there is not an established standard method for treating Broca's aphasia, a variety of methods are used to aid in the recovery process. Speech exercises can be performed to speed up the recovery process to gain back certain language abilities, and can be integrated with other methods such as pharmacotherapy or transcranial magnetic stimulation. During pharmacotherapy, aphasic patients take drugs that act on a number of neurotransmitter systems in the brain. Drugs such as dexamphetamine and methylphenidate act on dopamine (both are dopaminergic psychostimulants), while donepezil and bifemelane act on acetylcholine (both are cholinergic drugs). In transcranial magnetic stimulation, magnetic fields are noninvasively used to stimulate specific brain regions, which can aid in the recovery process. Additionally, patients may undergo treatment therapies such as impairment-based therapies, including melodic intonation therapy, and constraint-induced therapy . Melodic intonation therapy treats patients through the use of singing to improve language ability, whereas constraint-induced therapy focuses on rewiring the brain to regain lost speech abilities.
Advocacy and Awareness
If you would like more information on how to get involved in helping patients with Broca’s aphasia, please contact the National Aphasia Association or visit their website at http://www.aphasia.org/.
Paul Broca - French physician who conducted research that provided the initial evidence of brain function localization
Tan - Patient whose brain damage lead to the discovery of Broca’s aphasia by Paul Broca in 1861
Broca’s area- Brain region responsible for production of meaningful speech that is located in the inferior frontal gyrus
Cerebral hemorrhage - Type of stroke resulting in bleeding from ruptured brain blood vessels
Extradural hematoma - Type of traumatic brain injury characterized by a buildup of blood between the skull and dura mater
Boston Diagnostic Aphasia Examination- Diagnostic battery used to test for aphasia in patients
Western Aphasia Battery - Diagnostic battery used to test the language skills of aphasic patients
Porch Index of Speech Ability - Diagnostic test used to differentiate between types of aphasia
Pharmacotherapy- Treatment of aphasia or other diseases through using prescription drugs
Transcranial magnetic stimulation- Method used to stimulate brain regions with magnetic fields
Dopaminergic psychostimulants - Drugs that act to increase the levels of the neurotransmitter dopamine in the brain
Cholinergic drugs - Drugs that inhibit the activity of the neurotransmitter acetylcholine
Melodic intonation therapy- Therapy intended to improve language ability through singing
Constraint-induced therapy- Therapy aimed at brain rewiring to regain speech abilities
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