Extradural abscess: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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Extradural abscess is an accumulation of pus between the dura mater and the bones of the skull.
The pathogenesis of the extradural abscess
Extradural abscess occurs as a result of the spread of the inflammatory process from the mastoid process and the tympanic cavity to the cranial cavity and is localized in the posterior or in the middle cranial fossa. Extradural abscess can develop both with acute otitis and with exacerbation of chronic purulent otitis media. In such cases, during radical surgery on the ear, cholesteatoma, pus in the tympanic cavity, often the destruction of the roof of the tympanic cavity is almost always observed, and in the localization of the extradural abscess in the posterior cranial fossa, the purulent labyrinthitis.
Symptoms of extradural abscess
The symptomatology of the extradural abscess is poor, and it is often diagnosed only during surgery. Extradural abscess, which occurs with acute purulent otitis, is often combined with the symptoms of mastoiditis. The general symptoms are not very pronounced. The main symptom of the extradural abscess is copious suppuration from the ear.
A constant symptom of the ectradural abscess is not a very intense headache. Headache is localized with a perisinus abscess in the occipital and frontal areas, with an abscess of the middle cranial fossa in the region of scales of the temporal bone, in the tail area and in the region of the tragus. With a deeper location of the abscess, with the involvement of the gasser node or its branches in the process, the occurrence of trigeminal pain in the facial region is possible. With extradural abscess and posterior cranial fossa, the pains are localized in the neck region. Sometimes with this localization of the abscess due to pain and dizziness develops torticollis.
Headache in some patients is accompanied by nausea, vomiting, drowsiness. The general condition can be either satisfactory or severe.
Diagnosis of extradural abscess
Physical examination
Body temperature is usually normal or subfebrile even if there is a perisinus abscess. A sharp rise in temperature almost always indicates the development of meningitis or sinustrombosis. The pulse frequency, as a rule, corresponds to the temperature, the bradycardia is rarely observed.
In the physical examination of the patient, it is possible to detect meningeal symptoms: mild rigidity of the occipital muscles, Kernig symptom, more often expressed on the side of the abscess.
Seldom have focal symptoms. When localized in the middle cranial fossa, they are in the form of paresis of opposite extremities, a violation of sensitivity in them, focal epileptic seizures. Two-sided paresis usually indicates the involvement of the soft dura mater in the process. When localizing the extradural abscess in the posterior cranial fossa, nystagmus is noted, coordination disorders in the homolateral limbs, and a low muscular tone in them. With a deep location of the abscess, which descends to the base, a paresis of the abducent nerve is observed on the side of the abscess.
Laboratory research
Blood tests without abnormalities. ESR is not increased. Changes in blood are observed only with extensive pachymeningitis. The composition of cerebrospinal fluid, as a rule, is not changed.
Instrumental research
The most effective diagnostic methods for extradural abscess are CT, MRI. In the absence of these methods, craniography,
Craniographic diagnosis of extradural abscesses is based on the identification of indirect radiographic signs, primarily the displacement of the calcified pineal gland. It is determined on the craniograms in a direct projection, as in the norm it is located along the middle line.
In cerebral angiography, the reliable signs of extradural abscesses are the displacement of medially, together with the dura mater, the vessels located on the convex surface of the cerebral hemisphere, from the inner surface of the skull to the formation of an avascular zone.
In CT and MRI, extradural abscesses are diagnosed as a biconvex, flat concave or crescent zone of a changed density (for CT) and an MP signal (for MRI) adjacent to the bones of the skull. In this case, the pathogenic signs of the extradural abscess are revealed: displacement of the dura mater from the bones of the skull. At CT, extradurate abscesses, as a rule, have an increased density within 60-65 HU.
Differential diagnostics
During the surgical treatment of the extradural abscess, differential diagnosis with intracerebral and subdural abscesses is necessary.
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