====== Apraxia of lid opening ======

Apraxia of [[lid opening]] (ALO) is an inability to initiate voluntary [[eyelid]] opening following a period of eyelid closure, with normal function at other times. Manual lifting of the eyelid often resolves the problem and the lid is able to stay open.

Involuntary [[eyelid closure]] (IEC) may occur after [[subthalamic nucleus deep brain stimulation]] of the in [[Parkinson's disease]] (PD) and is often categorised as [[apraxia]] of lid opening (ALO), albeit the appropriateness of this term is under debate. To gain insight into the hitherto undefined pathophysiology of IEC after STN-DBS, Weiss et al., performed a comprehensive clinical and electrophysiological characterisation of lid function in a total of six PD patients.

The study was carried out in six PD patients who developed IEC after STN-DBS. They underwent neurological examination and electromyography recording of activity in the orbicularis oculi muscle (OO) upon varying stimulation patterns. Intraoperative studies were performed in one patient.

Increasing STN-DBS intensity induced IEC in four patients, whereas it improved the condition in two. Needle EMG showed tonic hyperactivity of the OO in STN-DBS induced IEC, while variable patterns of OO activity (irregular and tonic) were seen in patients with STN-DBS-relieved IEC. Intraoperative analysis in one patient showed evidence for IEC being induced by activation of corticobulbar fibres.

They identified two groups of IEC after STN-DBS based on clinical and EMG patterns: (1) STN-DBS induced IEC associated with tonic OO overactivity and (2) STN-DBS relieved IEC presenting with variable EMG patterns. The findings provide relevant information on pathophysiology of STN-DBS related IEC and implications for its therapeutic management
((Weiss D, Wächter T, Breit S, Jacob SN, Pomper JK, Asmus F, Valls-Solé J,
Plewnia C, Gasser T, Gharabaghi A, Krüger R. Involuntary eyelid closure after
STN-DBS: evidence for different pathophysiological entities. J Neurol Neurosurg
Psychiatry. 2010 Sep;81(9):1002-7. doi: 10.1136/jnnp.2009.196691. Epub 2010 Jun
20. PubMed PMID: 20562465.
)). 

Goto et al.,reported that globus pallidus internus deep brain stimulation on the right side markedly alleviates ALO as well as gait freezing in a patient with Parkinson's disease
((Goto S, Kihara K, Hamasaki T, Nishikawa S, Hirata Y, Ushio Y. Apraxia of lid
opening is alleviated by pallidal stimulation in a patient with Parkinson's
disease. Eur J Neurol. 2000 May;7(3):337-40. PubMed PMID: 10886319.
)).