Hereditodegenerative Disorders

Degenerative dementias

Alzheimer's disease

33

Pick's disease

Corticobasal ganglionic degeneration

Movement disorders

Goricobasal ganglionic degeneration

34

NEUROVASCULAR DISORDERS

Ischemic/hemorrhagic infarction

45

Arteriovenous malformation

NEOPLASTIC DISORDERS

Primary neurological tumors

Astrocytoma/glioblastoma/oligodendroglioma/meningioma

46

Metastatic neoplasms and paraneoplastic syndromes

Metastatic disease

47

TRAUMATIC DISORDERS

Blunt or penetrating CNS trauma

51

of movements involved in gestures, including emblems and pantomimes. Two forms of ideomotor apraxia can be identified. A posterior form can be induced by left parietal cortex (angular or supramarginal gyrus) lesions, while an anterior form can occur following lesions anterior to the supramarginal gyrus that disconnect the visual kinesthetic motor engrams from the premotor and motor areas. Patients with posterior IMA have difficulty performing in response to command and imitation and do not discriminate well between poorly and well-performed acts. Patients with the anterior type of IMA also perform poorly to command or imitation but can comprehend and discriminate pantomimes (see T§ble..,..4.-1).

When performing skilled acts, patients with IMA make primarily spatial and temporal production errors (see T.ab!e.,.4.-2 ). Spatial errors can be divided into postural (or internal configuration), spatial orientation, and spatial movement subtypes. Postural errors are seen in patients with apraxia when they are asked to pantomime a skilled motor task and use a body part as a tool rather than acting as if they were using the particular implement. y For example, when certain patients with IMA are asked to pantomime the use of a pair of scissors, they may use their fingers for the blades. Although many normal subjects can make similar errors, it is important to instruct the patient specifically not to use a body part as a tool. Unlike normal subjects, patients with IMA continue to use their body parts as tools despite these instructions.1«]

Also unlike normal subjects, who, when asked to use a tool, orient that tool to an imaginary target of the tool's action, patients with IMA often fail to orient their forelimbs to the imaginary target. These are errors of spatial orientation. As an example, when asked to pantomime cutting a piece of paper with scissors, rather than keeping the scissors oriented in the sagittal plane, IMA patients may either orient the scissors laterally, y or they may not maintain any consistent plane.

When patients with IMA attempt to make a learned skilled movement, they often make the correct core movement (e.g., twisting, pounding, cutting), but their limb moves through space incorrectly. y , y These spatial movement errors are caused by incorrect joint movements. Apraxic patients often stabilize a joint that they should be moving and move joints that should not be moving. For example, when pantomiming the use of a screwdriver, the patient with IMA may rotate his arm at the shoulder and fix his elbow. Shoulder rotation moves the hand in arcs when the hand should be rotating on a fixed axis. When multiple joint movements must be coordinated, the patient with apraxia may be unable to coordinate these actions to achieve the desired spatial trajectory. For example, when asked to pantomime slicing bread with a knife, both the shoulder and elbow joints must be alternately flexed and extended. However, when the shoulder flexes, the elbow should extend. When the joint movements are not well coordinated, patients may make primarily chopping or stabbing movements.

Patients with IMA may also make timing errors, including long delays before initiating a movement and brief multiple stops (stuttering movements), especially when changing direction.^ In addition, when normal subjects make a curved movement, they reduce the speed of the

movement, and when they move in a straight line, they increase the speed. Patients with IMA, however, do not demonstrate a smooth sinusoidal hand speed when performing cyclical movements such as cutting with a knife.

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