Spontaneous remission of papilledema and sixth nerve palsy in acute lymphoblastic leukemia

Color vision predicts processing modes of goal activation during action cascading

One of the most important functions of cognitive control is action cascading: the ability to cope with multiple response options when confronted with various task goals. A recent study implicates a key role for dopamine (DA) in this process, suggesting higher D1 efficiency shifts the action cascading strategy toward a more serial processing mode, whereas higher D2 efficiency promotes a shift in the opposite direction by inducing a more parallel processing mode (Stock, Arning, Epplen, & Beste, 2014). Given that DA is found in high concentration in the retina and modulation of retinal DA release displays characteristics of D2-receptors (Peters, Schweibold, Przuntek, & Müller, 2000), color vision discrimination might serve as an index of D2 efficiency. We used color discrimination, assessed with the Lanthony Desaturated Panel D-15 test, to predict individual differences (N = 85) in a stop-change paradigm that provides a well-established measure of action cascading. In this task it is possible to calculate an individual slope value for each participant that estimates the degree of overlap in task goal activation. When the stopping process of a previous task goal has not finished at the time the change process toward a new task goal is initiated (parallel processing), the slope value becomes steeper. In case of less overlap (more serial processing), the slope value becomes flatter. As expected, participants showing better color vision were more prone to activate goals in a parallel manner as indicated by a steeper slope. Our findings suggest that color vision might represent a predictor of D2 efficiency and the predisposed processing mode of goal activation during action cascading.

Unusual causes of papilledema: Two illustrative cases

Background:

Neurosurgeons are frequently among the first physicians asked to evaluate patients with papilledema, and the patient is often referred with the implication that they may require shunting. After an initial evaluation to exclude potential neurosurgical emergencies, the physician should carefully consider various etiologies of papilledema to prevent unnecessary neurosurgical operations.

Case Description:

The authors report two illustrative cases of unusual causes of papilledema: Anemia and leukemic infiltration of the central nervous system. In each case, a complete blood count provided clues for the diagnosis. A review of the literature is also included.

Conclusions:

Both patients responded to medical management/treatment of the underlying disease and did not require neurosurgical operative intervention. Papilledema may be caused by other etiologies besides increased intracranial pressure. The authors present two unusual cases leading to papilledema and provide an outline for the workup of these conditions.

Acquired colour deficiency in patients with Parkinson's disease

The blue cone pathway is reported to be affected early in Parkinson's disease (PD) and acquired type three (tritan) defects may occur. Sixty-one patients attending a treatment and rehabilitation centre for PD were examined with clinical colour vision tests. Seven of 13 patients, for whom the diagnosis of PD was equivocal or who had other medical conditions, were identified as having tritan colour deficiency. Results for the remaining 44 PD patients were compared with 40 age matched controls. Ten PD patients (22.7%) had tritan defects. Tritan defects were not found in the control group but performance on some tests was age related. We conclude that clinical tests for tritan colour deficiency are unlikely to be helpful in identifying PD.

Colour discrimination thresholds in Parkinson's disease: results obtained with a rapid computer-controlled colour vision test

A dysfunction of dopaminergic retinal neurons is thought to occur in Parkinson's disease, manifesting itself in impaired performance on various visual discrimination tasks. We have investigated whether differences in colour discrimination could readily be detected between a normal group and a Parkinsonian group, using a computer-controlled test of colour vision. Although some individual Parkinsonian patients showed an abnormal elevation of colour discrimination thresholds, there was no significant difference between the normal group and the Parkinsonian group.