[SANDO].

Movement disorders or basal ganglia injury have not been reported as complications of the ketogenic diet, an alternative treatment for intractable epilepsy. We report on a novel complication of the ketogenic diet manifesting as a severe extrapyramidal movement disorder and bilateral putaminal lesions. A single case is described. A video demonstrating the movement disorder is included. A 5-year-old girl with a cryptogenic epileptic encephalopathy developed focal dystonia, diffuse chorea, and ataxia after starting the ketogenic diet. Cranial magnetic resonance imaging (MRI) demonstrated bilateral putaminal lesions that were not present before starting the diet. MR spectroscopy showed a lactate peak in the basal ganglia, suggesting a failure of mitochondrial energy metabolism as the mechanism of cerebral injury. The radiographic abnormalities resolved after stopping the diet, although the movement disorder persisted. Basal ganglia injury and extrapyramidal movement abnormalities are potential complications of the ketogenic diet. Concomitant use of valproate or a latent inborn error of metabolism may be risk factors for these rare complications.

Ataxia↗

PubMed2003

A coupled oscillator model of disordered interlimb coordination in patients with Parkinson's disease.

Coordination between the left and right limbs during cyclic movements, which can be characterized by the amplitude of each limb's oscillatory movement and relative phase, is impaired in patients with Parkinson's disease (PD). A pedaling exercise on an ergometer in a recent clinical study revealed several types of coordination disorder in PD patients. These include an irregular and burst-like amplitude modulation with intermittent changes in its relative phase, a typical sign of chaotic behavior in nonlinear dynamical systems. This clinical observation leads us to hypothesize that emergence of the rhythmic motor behaviors might be concerned with nonlinearity of an underlying dynamical system. In order to gain insight into this hypothesis, we consider a simple hard-wired central pattern generator model consisting of two identical oscillators connected by reciprocal inhibition. In the model, each oscillator acts as a neural half-center controlling movement of a single limb, either left or right, and receives a control input modeling a flow of descending signals from higher motor centers. When these two control inputs are tonic-constant and identical, the model has left-right symmetry and basically exhibits ordered coordination with an alternating periodic oscillation. We show that, depending on the intensities of these two control inputs and on the difference between them that introduces asymmetry into the model, the model can reproduce several behaviors observed in the clinical study. Bifurcation analysis of the model clarifies two possible mechanisms for the generation of disordered coordination in the model: one is the spontaneous symmetry-breaking bifurcation in the model with the left-right symmetry. The other is related to the degree of asymmetry reflecting the difference between the two control inputs. Finally, clinical implications by the model's dynamics are briefly discussed.

Ataxia↗