Biomedical subjects
J A de Groot
Publications and source records attributed to J A de Groot.
Dehiscence of the jugular bulb in Crouzon's disease.
Patients with Crouzon's disease have a distorted nasopharynx, which frequently leads to retained middle ear secretions and necessitates myringotomy. A review of the computed tomographic (CT) scans of 21 ears in 11 patients with Crouzon's disease found that 12 jugular bulbs were protruding or dehiscent. The relationship between the jugular bulb and the middle ear space was normal bilaterally in only 2 of the 11 patients. Consequently, patients with Crouzon's disease are at risk for inadvertent puncture of the jugular bulb during myringotomy. CT scans obtained prior to myringotomy can be helpful in detecting dehiscent or protruding jugular bulbs.
Chemotherapy with doxorubicin and CCNU in advanced undifferentiated carcinoma of the nasopharynx. A retrospective report on five patients.
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[Feasibility of high resolution CT in the demonstration of the vestibular aqueduct (Ménière) and otospongiosis of the labyrinth].
Ever since the introduction of temporal bone imaging by means of high-resolution CT, it appears that the combination of high spatial resolution, high density resolution and the freedom of patient positioning for scanning of optimal otological planes may play a unique role in the diagnosis and follow-up of a number of otological disorders. Two examples are described here. The first is the possibility of determining whether the vestibular aqueduct in idiopathic Ménière's disease is obliterated or not, and if so, whether it is a bony or a fibrous obliteration. Although the results are preliminary, there are indications that all three cathegories occur and that the efficacy of drainage of the endolymphatic sac can be evaluated prior to surgery. The second example is the possibility of outlining and quantifying the bone mineral loss in cases of labyrinthine otospongiosis. Preliminary studies have outlined that there is a relationship between the degree of decalcification and the severity of sensorineural hearing loss. These examples show high-resolution, thin-section multiplanar CT to have great potential in the diagnosis and treatment of otological disorders. This will become evident as the techniques that were used here are worked out in more detail and become more widely known.
CT of cochlear otosclerosis (otospongiosis).
High-resolution CT is the method of choice in determining the extent of demineralization in otospongiosis. By comparing the maximum and minimum densities, this examination has become of clinical importance in the diagnostic approach to otosclerosis and in the follow-up of fluorine therapy.
The value of the direct semi-longitudinal CT-plane (Zonneveld) in the preoperative evaluation of petrous bone pathology. A new otological approach.
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The value of the direct semi-longitudinal CT-plane in the preoperative evaluation of petrous bone pathology.
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Densitometry of the cochlear capsule and correlation between bone density loss and bone conduction hearing loss in otosclerosis.
Radiodensity of the bony cochlear capsule was investigated by CT-scanning in 134 ears with otosclerosis and 35 normal control ears. A technique of densitometry of the cochlea was developed comprising the measurement of maximum and minimum density together with mapping of the cochlea and measurement of the density at six predefined points in the cochlear capsule. Bone density in the normal cochlea showed very little interindividual variation. In the otosclerosis patients, minimum density was decreased in 58% of the ears, indicating the presence of a focus. At visual examination, foci were only detectable when density loss exceeded 200 Hounsfield. A positive correlation was found between bone density loss and bone conduction hearing loss with a maximum at 2,000 Hz and the medioventral point of the cochlear wall. The method appears to be useful for the follow-up during fluoride treatment, as is demonstrated by a case report.
Labyrinthine otosclerosis studied with a new computed tomography technique.
Forty-two patients (84 ears) with surgically confirmed otosclerosis were examined with a computerized tomographic scanner (Philips Tomoscan 310) equipped with a table swivel mechanism. All ears were scanned in the horizontal and a new semilongitudinal plane. In patients with an unimpaired bone conduction threshold, a normal labyrinthine capsule was found in all ears except two. Normal bone conduction does not exclude extensive labyrinthine otospongiosis. In cases with bone conduction impairment, the bony labyrinth appeared normal in about half the ears. In the other half, areas of bone resorption were present and a positive correlation was found between the degree of bone loss and the amount of bone conduction threshold loss.