Benedikt syndrome

Benedikt syndrome, also called Benedikt's syndrome or paramedian midbrain syndrome, is a rare type of posterior circulation stroke of the brain, with a range of neurological symptoms affecting the midbrain, cerebellum and other related structures.

Signs and symptoms
It is characterized by the presence of
 * Ipsilateral Oculomotor nerve (CN III) palsy
 * Contralateral hemiparesis
 * Contralateral Cerebellar ataxia including tremor and involuntary choreoathetotic movements.

Neuroanatomical structures affected include the oculomotor nucleus, red nucleus, corticospinal tracts and superior cerebellar peduncle decussation. It has a similar cause, morphology, signs and symptoms to Weber's syndrome; the main difference between the two being that Weber's is more associated with hemiplegia (i.e. paralysis), and Benedikt's with ataxia (i.e. disturbed coordination of movements).

While both Benedikt's and Claude's syndrome share some similarities, they can be differentiated based on the type of movement impairment they cause. Benedikt's syndrome is characterized by more prominent tremors and involuntary, writhing movements (choreoathetosis), whereas Claude's syndrome is primarily marked by difficulties with coordination and balance (ataxia).

Causes
Benedikt syndrome is caused by a lesion (infarction, hemorrhage, tumor, or tuberculosis) in the tegmentum of the midbrain and cerebellum. Specifically, the median zone is impaired. It can result from occlusion of the posterior cerebral artery or paramedian penetrating branches of the basilar artery.

Diagnosis

 * Oculomotor nerve palsy: eyeball gazing downward and outward position, diplopia, miosis, mydriasis, and loss of accommodation reflex.
 * Contralateral loss of proprioception and vibration sensations.
 * Cerebellar ataxia: involuntary movements.

Treatment
Deep brain stimulation may provide relief from some symptoms of Benedikt syndrome, particularly the tremors associated with the disorder.