Mental Status

Mental – Anatomy

Introduction

The cerebral hemispheres represent the highest and most complex level of neurological function. There is so much integration of cortical function that whatever system is used to clinically “examine” the cerebral hemispheres will be an over simplification and somewhat artificial compartmentalization. Although a lot of mental status reflects integration of cortical function, it can still be divided into parts that correspond to the divisions of the cerebral hemispheres. This anatomy review will be a brief overview of areas of cortical function that can be examined by components of the mental status exam.

Fontal Lobes

The frontal lobes are important for attention, executive function, motivation, and behavior. Tests for frontal lobe function include working memory (digit span, spelling backward), judgment, fund of knowledge, task organization and set generation such as naming lists of things in a certain category.

Temporal Lobes

The temporal lobes are important for emotional response (amygdala and its connections to the hypothalamus and frontal lobes) and memory (hippocampus and limbic connections). Clinically the main tests for temporal lobe function are those of memory, particularly declarative memory.

Language – Temporal and Frontal Lobes

The principle area for receptive language is Wernicke’s area, which is located in the posterior part of the superior temporal gyrus of the dominant temporal lobe. The major region for expressive language is Broca’s area located in posterior part of the inferior frontal gyrus of the dominant hemisphere. Homologous regions of the non-dominant hemisphere are important for the non-verbal contextual and emotional aspects as well as the prosody (rhythm) of language. Tests for written and spoken receptive and expressive language are used to “view” these language centers.

Parietal Lobes

The parietal lobes are important for perception and interpretation of sensory information especially somatosensory information. The non-dominant parietal lobe is particularly important for visual-spatial function. The dominant parietal lobe is important for praxis, which is the formation of the idea of a complex purposeful motor act while the frontal lobes are important for the execution of the act. The Gerstmann syndrome, which consists of the constellation of acalculia, finger agnosia, right-left confusion and agraphia, occurs with damage to the dominant inferior parietal lobe. Clinical tests for parietal lobe function include tests for agnosia (such as inability to identify objects by tactile exploration), apraxia (inability to perform purposeful motor acts on command), constructional apraxia (inability to draw objects which require use of visual spatial organization) and testing for elements of Gerstmann’s syndrome.

Occipital Lobes

The occipital lobes are important for perception of visual information. Areas in the inferior temporal visual association cortex are important for recognition of color and shape as well as the recognition of faces. Projections from the occipital lobe to the superior temporal-parietal area are important for perceiving motion of objects. Tests that are used to examine the occipital lobes and its connections include visual fields (see Cranial Nerve 2), naming of objects, naming of colors and recognition of faces.

Potential Traps

1. There is more variability to the expression of lesions of the cerebral cortex than of structures more caudal in the neuroaxis.
2. Time of day, stress, fatigue, and pain can affect a patient’s performance on the mental status exam.
3. You need to consider the patient’s social and educational background when evaluating the results of the mental status exam.

Clinical Pearls

1. The mental status exam begins with listening and watching the patient during the history part of the examination.
2. The patient must be awake and alert in order to have a “window” to view the cortex. So assessment of the level of alertness and the intactness of the reticular activating system is actually the first step in the mental status assessment.

Mental – Normal Exam

Orientation, Memory

Asking questions about month, date, day of week and place tests orientation, which involves not only memory but also attention and language. Three-word recall tests recent memory for which the temporal lobe is important. Remote memory tasks such as naming Presidents, tests not only the temporal lobes but also heteromodal association cortices.

Attention – Working memory

Digit span, spelling backwards and naming months of the year backward test attention and working memory which are frontal lobe functions.

Judgement – Abstract reasoning

These frontal lobe functions can be tested by using problem solving, verbal similarities and proverbs.

Set generation

This is a test of verbal fluency and the ability to generate a set of items which are frontal lobe functions. Most individuals can give 10 or more words in a minute.

Receptive language

Asking the patient to follow commands demonstrates that they understand the meaning of what they have heard or read. It is important to test reception of both spoken and written language.

Expressive language

In assessing expressive language it is important to note fluency and correctness of content and grammar. This can be accomplished by tasks that require spontaneous speech and writing, naming objects, repetition of sentences, and reading comprehension.

Praxis

The patient is asked to perform skilled motor tasks without any nonverbal prompting. Skills tested for should involve the face then the limbs. In order to test for praxis the patient must have normal comprehension and intact voluntary movement. Apraxia is typically seen in lesions of the dominant inferior parietal lobe.

Gnosis

Gnosis is the ability to recognize objects perceived by the senses especially somatosensory sensation. Having the patient (with their eyes closed) identify objects placed in their hand (stereognosis) and numbers written on their hand (graphesthesia) tests parietal lobe sensory perception.

Dominant parietal lobe function

Tests for dominant inferior parietal lobe function includes right-left orientation, naming fingers, and calculations.

Non-dominant parietal lobe function

The non-dominant parietal lobe is important for visual spatial sensory tasks such as attending to the contralateral side of the body and space as well as constructional tasks such as drawing a face, clock or geometric figures.

Visual recognition

Recognition of colors and faces tests visual association cortex (inferior occiptotemporal area). Achromatopsia (inability to distinguish colors), visual agnosia (inability to name or point to a color) and prosopagnosia (inability to identify a familiar faces) result from lesions in this area.

Mental – Abnormal

Orientation, Memory

This patient has difficulty with orientation questions. The day of the week is correct but he misses the month and date. He is oriented to place. Orientation mistakes are not localizing but can be due to problems with memory, language, judgement, attention or concentration. The patient has good recent memory (declarative memory) as evidenced by the recall of three objects but has difficulty with long term memory as evidenced by the difficulty recalling the current and past presidents.

Attention – Working memory

The patient has difficulty with digit span backwards, spelling backwards and giving the names of the months in reverse order. This indicates a problem with working memory and maintaining attention, both of which are frontal lobe functions.

Judgement – Abstract reasoning

The patient gives the correct answer for a house on fire and his answers for similarities are also good. He has problems with proverb interpretation. His answers are concrete and consist of rephrasing the proverb or giving a simple consequence of the action in the proverb. Problems with judgement, abstract reasoning, and executive function can be seen in patients with frontal lobe dysfunction.

Set generation

Set generation tests word fluency and frontal lobe function. The patient starts well but abruptly stops after only four words. Most individuals can give more then 10 words in one minute.

Receptive language

Patients with a receptive aphasia (Wernicke’s) cannot comprehend language. Their speech output is fluent but is devoid of meaning and contains nonsense syllables or words (neologisms). Their sentences are usually lacking nouns and there are paraphasias (one word substituted for another). The patient is usually unaware of their language deficit and prognosis for recovery is poor.

This patient’s speech is fluent and some of her sentences even make sense but she also has nonsense sentences, made up of words and parts of words. She can’t name objects (anomia). She doesn’t have a pure or complete receptive aphasia but pure receptive aphasias are rare.

Expressive language

This patient with expressive aphasia has normal comprehension but her expression of language is impaired. Her speech output is nonfluent and often limited to just a few words or phases. Grammatical words such as prepositions are left out and her speech is telegraphic. She has trouble saying “no ifs , ands or buts”. Her ability to write is also effected.

Patients with expressive aphasia are aware of their language deficit and are often frustrated by it. Recovery can occur but is often incomplete with their speech consisting of short phrases or sentences containing mainy nouns and verbs.

Praxis

The patient does well on most of the tests of praxis. At the very end when he is asked to show how to cut with scissors he uses his fingers as the blades of the scissors instead of acting like he is holding onto the handles of the scissors and cutting. This can be an early finding of inferior parietal lobe dysfunction.

Gnosis

With his right hand the patient has more difficulty identifying objects then with his left hand. One must be careful in interpreting the results of this test because of the patient’s motor deficits but there does seem to be astereognosis on the right, which would indicate left parietal lobe dysfunction. This is confirmed with graphesthesia where he definitely has more problems identifying numbers written on the right hand then the left (agraphesthesia of the right hand).

Dominant parietal lobe function

This patient has right-left confusion and difficulty with simple arithmetic. These are elements of the Gertsmann syndrome, which is seen in lesions of the dominant parietal lobe. The full syndrome consists of right-left confusion, finger agnosia, agraphia and acalculia.

Non-dominant parietal lobe function

The patient’s drawing of a clock demonstrates a problem with visuospatial construction tasks, which reflects parietal lobe dysfunction. He doesn’t neglect the left side of space but he lists the numbers of the clock in two columns and then draws a line between the 8 and the 3 for 8:15.

Visual recognition

Colors are correctly identified but the patient has difficulty correctly identifying the face of a president that he is familiar with. Further testing would be necessary to make sure this is prosopagnosia rather then a problem with attention or long term memory.