Anatomy-Lexicon

Cerebellar bridge angle

Anatomy of the cerebellopontine angle

The cerebellar bridge angle (angulus pontocerebellaris) is the name of a specific anatomical structure of the brain. It lies between the brain stem (consisting of midbrain = mesencephalon, hindbrain = rhombencephalon and bridge = pons) and the cerebellum (cerebellum) and temporal bone.
It is located in the posterior fossa. The cerebellopontine angle represents a niche through which important cranial nerves pass in a narrow space.
The intermediate nerve and the facial nerve (together form the 7th cranial nerve) as well as the vestibulicochlear nerve (the 8th cranial nerve) arise here from the brain structure and move to their supply areas.
Further information on this topic can be found on our website Cranial nerves.

In addition, the inferior cerebellar anterior and posterior cerebellar arteries pass through the cerebellopontine angle.
Cerebral veins belonging to the sinus petrosi also pass through. The cerebellar bridge angle is so well known because tumors can often occur in this region, which quickly become symptomatic (cranial nerve failure) due to the narrow anatomical situation.

Tumors in the cerebellopontine angle

Masses in the cerebellopontine angle are evident from early symptoms. The diagnosis of choice is an MRI. Often the tumors are benign. But due to the anatomical tightness in the cerebellopontine angle, their growth presses on the cranial nerves running along there and thus leads to cranial nerve failure.
To understand the symptoms of failure, one has to know what functions the cranial nerves have.

The 7thCranial nerve, the facial nerve innervates the muscles in the face with its motor fibers. If this fails, the patient has facial nerve palsy (one half of the face is drooping). The 8th cranial nerve, the vestibulocachlear nerve, is responsible for hearing and balance. If it is affected, the patient has a hearing loss and possibly tinnitus and dizziness. There are various tumors that can cause symptoms of space occupation.
The most common are acoustic neuromas (vestibular schwannoma), but also meningiomas, epidermoids, glomus jugulare tumors and brain metastases. The acoustic neuroma is a benign tumor of the Schwann cells of the 8th cranial nerve. It can also be located in the internal auditory canal, which is more common than its location in the cerebellopontine angle.
The patients complain of a hearing loss, often associated with dizziness and tinnitus.
Further information on this topic can be found on our website Acute neuroma and Meningioma.

If the tumor has a certain size, it can press on the 7th cranial nerve and trigger facial paralysis. The 5th cranial nerve, the trigeminal nerve, which can also be in close proximity to the tumor, can also be affected. This can lead to a sensitization disorder in the face, up to and including trigeminal neuralgia. If the tumor is advanced, brain stem compression is possible. There is increased intracranial pressure, which manifests itself as headache, vomiting and impaired consciousness.
The first choice therapy is surgery. The aim is to maintain the cranial nerve function, so an operation should be carried out in good time, as long as the nerves have not yet suffered permanent damage from the pressure. The operation can be performed from the posterior fossa or the auditory canal (the location of the tumor is ultimately decisive here). Such an operation takes a few hours. If the risk of surgery is too high for old, unstable patients, radiosurgery can be performed

Read more on this topic at: Facial palsy

More brief information on the other tumor types

Meningiomas are tumors that originate from the meninges.
Epidermoids are congenital, rare tumors.
Glomus jugular tumors originate from the paraganglia in the pit of the temporal bone (fossa jugularis).
Brain metastases are daughter tumors, the primary tumors are often lung cancer, breast cancer, kidney cell cancer and black skin cancer.

Read more on the topic at: Brain Cancer and Brain Cancer Signs

Cerebellar bridge angle syndrome

The cerebellar bridge angle syndrome is a combination of symptoms that can occur with tumors in the cerebellar bridge angle (see cerebellar bridge angle tumors).
The symptoms can be derived from the anatomy of the cerebellopontine angle.
Symptoms include: hearing loss, tinnitus, dizziness, unsteady gait (8th cranial nerve = vestibulocochlear nerve), unilateral facial paralysis, i.e. facial muscle paralysis (7th cranial nerve = facial nerve). Parasitic sensations through to trigeminal neuralgia, i.e. facial pain (5th cranial nerve = tirgeminus nerve) usually only occur with larger tumors.
The 6th cranial nerve (abducens nerve) can also be affected, which leads to eye muscle paralysis.
If the findings are pronounced, brainstem compression (nausea, vomiting and impaired consciousness) and cerebellar symptoms (cerebellar gait insecurity) can occur. The intracranial pressure increases progressively.

Additional information

Further information on the subject can be found at: