Closure of the PICA

PICA is the abbreviation for the lower posterior cerebellar artery with the Latin name Arteria inferior posterior cerebelli. It originates from the basilar artery, which is formed by the fusion of the two vertebral arteries. The PICA supplies the lower (caudal) part of the cerebellum, where it releases two smaller branches for blood supply.

If the blood supply in this area is disrupted, whether by arterial occlusion or bleeding, the functions of the cerebellum are also impaired there. Since the nerves‘ pathways are very close together, it is not possible to predict exactly what symptoms will occur. However, the most likely symptoms of PICA occlusion are disturbances of balance and the resulting problems in coordinating movements on the affected side (hemiataxy). Hoarseness and speech difficulties may also occur. Dysdiadochokinesis (see symptoms) occurs on the same side.

Symptoms

A cerebellar infarction can cause various symptoms that are characteristic of a functional failure of this area of the brain. Thus many cerebellar infarctions can be distinguished from strokes in the cerebrum. Since the planning and coordination of movements are controlled by the cerebellum, a so-called cerebellar ataxia (disorder in the cerebellum) develops.

Patients have an unsteady gait, seeming almost drunk. This can go so far that even sitting upright becomes impossible due to the swaying. The eyes and the sense of balance are strongly linked in the brain.

The cerebellum is also part of this network. In the event of a failure, the so-called nystagmus, a gaze stabilization disorder, occurs. Those affected describe the symptom as restlessness or trembling of the eyes.

The reason for this is the brain‘s attempt to adapt the eye movement to the incorrectly perceived body movement. However, the body does not actually move – the disturbance of the sense of balance gives the brain a false state. Another symptom of a cerebellar infarction can be intention tremor.Tremor describes the rhythmic movement of a body part.

Intention means that the tremor is intensified especially at the end of a movement. If a patient suffering from intention tremor taps his nose with his eyes closed, the movement becomes more and more random the closer he gets to the nose. The so-called dysdiadochokinesis is also a result of the disturbed movement coordination.

This means that opposing movements can no longer be performed smoothly. If you ask an affected person to pretend, for example, that he/she wants to screw in a light bulb, the movement appears very choppy and becomes less and less effective through multiple repetitions. In addition to these symptoms, speech problems can also occur – choppy (chanting) speech and impaired articulation (dysarthria), muscle weakness (muscle hypotonia), but also excessive (hypermetry) or too short movements (hypometry) (collectively referred to as dysmetry/mismotion).

Due to the proximity of the cerebellum to the cerebrospinal fluid (CSF = cerebrospinal fluid), an extensive cerebellar infarction can lead to a narrowing or closure of the system (especially of the 4th ventricle). A ventricular dislocation leads to increased intracranial pressure and hydrocephalus (a disturbance in the drainage of nerve water). Dizziness can be part of the clinical manifestation of a cerebellar infarction.

Since the cerebellum coordinates movements, the eye creates a connection to the environment and the organ of balance in the ear mediates the position of the body, these three systems are closely connected. Numerous nerve fibers form links so that movements can be executed in such a way that the person remains in balance. Only this complex system enables us, for example, to walk upright or to perform targeted movements at all.

In the case of a cerebellar infarction, these very pathways that connect the cerebellum with the control center of the vestibular nucleus can be affected. In the case of unilateral damage, the opposite organ of equilibrium may be activated excessively, as if the vestibular nerve had been damaged. No more stimuli or information is emitted from the damaged side. The body does not know in which position the affected side is located and the vestibular system goes crazy – the patient becomes dizzy.