Table 1. Clinical Characteristics of the Three Principal Frontal Lobe Syndromes

Orbitofrontal syndrome (disinhibited)

Disinhibited, impulsive behavior (pseudopsychopathic)
Inappropriate jocular affect, euphoria
Emotional lability
Poor judgment and insight
Distractibility

Frontal convexity syndrome (apathetic)

Apathy (occasional brief angry or aggressive outbursts common)

Indifference

Psychomotor retardation

Motor perseveration and impersistence

Loss of self

Stimulus-bound behavior

Discrepant motor and verbal behavior

Motor programming deficits

• Three-step hand sequence
  Alternating programs
  Reciprocal programs
  Rhythm tapping
  Multiple loops

Poor word list generation
Poor abstraction and categorization
Segmented approach to visuospatial analysis

Medial frontal syndrome (akinetic)

Paucity of spontaneous movement and gesture

Sparse verbal output (repetition may be preserved)

Lower extremity weakness and loss of sensation

Incontinence

In some patients, paroxysmal behavior disorders are recorded. These tend to be short-lived, and may include episodes of confusion and, occasionally, hallucinations. They are thought to reflect transient disturbances of the frontolimbic connections. Following massive frontal lobe lesions, the so-called apathetico-akinetico-abulic syndrome may occur. Patients lie around, passive, unaroused, and unable to complete tasks or obey commands.

Further clinical signs associated with frontal lobe damage include sensory inattention in the contralateral sensory field, abnormalities of visual searching, echo phenomena, such as echolalia and echopraxia, confabulation, hyperphagia, and various changes of cognitive function. Lhermitte (13,14) has described utilization behavior and imitation behavior, variants of environmental dependency syndromes. These syndromes are elicited by offering patients objects of everyday use and observing that, without instruction, they will use them appropriately, but often out of context (for example, putting on a second pair of spectacles when one pair is already in place). They will also, without instruction, imitate an examiner's gestures, no matter how ridiculous.

EPILEPSY

The importance of making an accurate seizure diagnosis in patients with epilepsy has been accelerated in recent years by the use of advanced monitoring techniques such as videotelemetry. The more recent classification schemes of the International League Against Epilepsy recognize a major distinction between partial and generalized seizures (20) and between localization-related and generalized epilepsies. (21) In the latest classification (22) the localization-related epilepsies include frontal lobe epilepsies, in several different patterns. The general characteristics of these are shown in Table 2 and their subcategories in Table 3.

Table 2. International Classification of Epilepsies and Epileptic Syndromes

1. Localization-related (focal, local, partial) epilepsies and syndromes.

• 1.1 Idiopathic (with age-related onset)
  1.2 Symptomatic
  1.3 Cryptogenic
  

2. Generalized epilepsies and syndromes

• 2.1 Idiopathic (with age-related onset--listed in order of age)
  2.2 Cryptogenic or symptomatic (in order of age)
  2.3 Symptomatic
  

3. Epilepsies and syndromes undetermined as to whether they are focal or generalized.