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Biomedical subjects

M Gjuric

Publications and source records attributed to M Gjuric.

At least 19 recordsLinked to original sources
PubMed2001

[Metastasis of a spinal myxopapillary ependymoma to the inner auditory canal].

Ependymomas are usually benign tumors of the central nervous system that derive from the ependymal cells lining liquor-filled spaces. Myxopapillary ependymomas are a variant occurring almost exclusively in the region of the cauda equina. Histologically, these tumors are benign (WHO grade I). The following case describes the first reported spread of a spinal myxopapillary ependymoma into the internal auditory canal. The symptoms and diagnostic results are similar to other tumors of this location. There are no typical findings in the diagnostic imaging (CT, MRI). The extended middle cranial fossa approach was chosen for surgical treatment. Adjuvant radiotherapy is indicated in cases of incomplete resection or recurrence.

Adult↗
PubMed2000

Cavernous hemangioma of the internal auditory canal arising from the inferior vestibular nerve: case report and review of the literature.

OBJECTIVE: To describe a case of cavernous hemangioma arising from the inferior vestibular nerve, limited to the internal auditory canal. STUDY DESIGN: Retrospective case review and review of literature. SETTING: A tertiary referral clinic. INTERVENTIONS: Extended middle cranial fossa surgery. RESULTS: The hemangioma was completely resected through the extended middle cranial fossa approach. No serious complications occurred, and the hearing and the facial nerve function were preserved. CONCLUSIONS: Originating from the capillary plexus surrounding Scarpa's ganglion, this hemangioma has to be differentiated from intratemporal hemangioma at the geniculate ganglion. Because of extrinsic growth pattern, the potential for preservation of the facial nerve function is high if surgery is performed early. Complete resection through the extended middle fossa approach is the treatment of choice for cavernous hemangioma with limited extension into the cerebellopontine angle. It remains difficult to distinguish preoperatively from the more common tumors, and surgery is usually planned on assumption of vestibular schwannoma.

Adult↗
PubMed2000

[Diagnosis of glomus jugulare tumor recurrence with dynamic contrast medium flow in MRI].

PURPOSE: To evaluate the ability of dynamic MRI to differentiate residual tumor from scar after glomus jugulare (GJ) surgery. METHODS: 26 patients after GJ surgery were examined with dynamic contrast medium MRI on a 1.5 T Philips-Gyro-Scan NT. A T1-weighted TFE sequence was performed to localise the 5 slices for the dynamic study. Subsequently, a T1-weighted TFE sequence was used for the dynamic contrast medium study. We started contrast medium administration and TFE sequence at the same time. The time until acquisition of the first image was 7.4 s, and the interval between two images 7 s (total time 2.24 min). Intensity versus time studies were performed in the region of interest. RESULTS: 2 typical intensity versus time graphs were observed: residual tumors showed a rapid increase in signal intensity, followed by a "wash-out" phase, and a plateau phase in the later course. Scar showed a moderate increase in signal intensity, followed by a plateau phase on a low intensity level. In 9 patients, in whom tumor removal was subtotal, we saw the typical graph of a GJ tumor. 4 of 17 patients with complete tumor removal showed a typical graph like that of residual tumor, 13 of 17 patients showed the typical graph of a scar. CONCLUSION: With dynamic contrast medium MRI studies, differentiation between residual tumor and scar is possible in patients with prior GJ surgery.

Cicatrix↗
PubMed2000

Extended middle fossa surgery for meningiomas within or at the internal auditory canal.

OBJECTIVE: To show the clinical outcome in patients with meningioma within or at the internal auditory canal (IAC) operated on by the extended middle cranial fossa approach. STUDY DESIGN: Retrospective case review. SETTING: A tertiary referral center. PATIENTS: Twelve patients, 9 women and 3 men, whose ages ranged from 37 to 70 years (mean 57 years). One tumor was entirely intracanalicular, 5 had an intra-extracanalicular growth, 3 were centered at the posterior porus lip, and 3 tumors were localized in the midpetrosal region with spread into the IAC. INTERVENTION: Extended middle cranial fossa approach. MAIN OUTCOME MEASURES: Magnetic resonance imaging and computed tomography were used for follow-up and reevaluation of the operative sites. Facial nerve function and hearing were examined. RESULTS: Complete resection was achieved in 10 (83%) of 12 patients. The retrosigmoid approach was necessary to complete tumor resection in one patient, and in another, partial resection was done because of the en plaque type of tumor growth. There was one unexpected recurrence. All patients retained normal or near-normal facial nerve function postoperatively. Three patients were deaf before surgery, and preoperative hearing level was preserved in 42%. CONCLUSIONS: Attempted hearing preservation surgery is justified in patients with small tumors and preserved hearing, because tumor exposure and safety of resection are comparable with that of hearing-destructive procedures. Lateral extension of the tumor to the fundus does not prevent complete resection with preservation of function, and elective bone resections beyond the visible tumor margins seem not to substantially influence the tumor recurrence rates.

Adult↗
PubMed1998

The value of methylprednisolone in the treatment of an experimental sensorineural hearing loss following drill-induced ossicular chain injury: a randomized, blinded study in guinea-pigs.

In a previously established animal model a standardized drill-induced injury to the body of the incus was applied, and the effects on hearing were characterized by electrocochleography. In a placebo-controlled, randomized, blinded study methylprednisolone showed no protective effect in reducing or improving the auditory threshold shifts, which occurred within seconds after drilling and remained stable throughout the 5-week observation period. Therefore the otologic surgeon must pay close attention to avoiding any contact of a rotating burr with an ossicle in an intact ossicular chain.

Animals↗
PubMed1998

Effects of transforming growth factor-beta1 and basic fibroblast growth factor on proliferation of cell cultures derived from human vestibular nerve schwannoma.

The influence of transforming growth factor-beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) on growth of cell cultures derived from unilateral vestibular nerve schwannomas was investigated. Cell cultures were initiated from 9 schwannomas and characterized immunocytochemically with antibodies against S-100 and type IV collagen. The effects of TGF-beta1 and bFGF on DNA synthesis in chemically defined serum-free medium were assessed by measuring the incorporation of 5-bromo-2'-deoxy-uridine (BRDU) into cellular DNA. Cell proliferation was evaluated with an electronic cell counter. Reverse transcription polymerase chain reaction (RT-PCR) was performed using oligonucleotide primers specific for TGF-beta1 and TGF-beta2. TGF-beta1 stimulated DNA synthesis in a dose dependent manner. Maximal stimulation was observed at a concentration of 1 ng/ml, which induced a nearly 2-fold increase in DNA content. This effect was not seen when TGF-beta1 was added in the presence of neutralizing antibodies. In addition, antibodies against TGF-beta1 significantly reduced DNA synthesis in control cultures without supplemented exogenous growth factors. bFGF alone had no significant effects on DNA synthesis. In contrast, when TGF-beta1 and bFGF were added together, the mitogenic response was much greater than produced by TGF-beta1 alone. RT-PCR showed that the cultured cells expressed mRNA for both TGF-beta1 and TGF-beta2. We hypothesize that TGF-beta1 is an autocrine growth factor for human vestibular nerve schwannomas in culture. A similar mechanism might be involved in the growth of these tumors in situ.

Adult↗
PubMed1998

Gold prostheses for ossiculoplasty.

OBJECTIVE: To review the results of ossicular chain reconstruction with partial and total ossicular replacement prostheses made of gold. STUDY DESIGN: Retrospective case review. SETTING: A tertiary referral center. PATIENTS: Fifty-nine patients underwent surgery between November 1993 and February 1996 and underwent follow-up for at least 12 months. Tympanoplasty was performed because of cholesteatoma, chronic otitis media, adhesive otitis media, and trauma. INTERVENTION: Tympanoplasty and ossiculoplasty with partial or total replacement gold prostheses. MAIN OUTCOME MEASURE: The clinical and hearing results of ossiculoplasty. RESULTS: In 62% of the patients in whom partial ossicular replacement prostheses were used, the residual air-bone gap could be reduced to < or =20 dB. In cases with total ossicular replacement prostheses, the air-bone gap could be closed to < or =20 dB in 42%. Extrusion of the prosthesis occurred in 11 cases (19%) between 7 and 21 months after tympanoplasty. In most extrusion cases (55%), this was combined with a significant retraction of the tympanic membrane. Primary and staged procedures showed different extrusion rates. CONCLUSIONS: Hearing results in the current study are comparable to results described by other authors for synthetic middle ear prostheses. Implant rejection was never encountered, with the gold implants exhibiting a high biocompatibility. Nevertheless, prosthesis extrusion occurred rather often in the course of tympanic membrane retraction. Staging the surgery or different shaping of the prosthesis may be helpful to prevent prosthesis extrusion.

Adolescent↗
PubMed1997

[Function preserving surgery of glomus jugulare tumors. An achievable goal?].

In this retrospective study, oncologic and functional results of 24 patients treated for glomus jugulare tumor stages C and D are reported. The surgical approach used was a combined transmastoid-transcervical approach, which was modified according to individual tumor growth. As needed, this was combined with a transtemporal or retrosigmoid approach. Complete tumor removal resulted in a cure rate of 100%. Surgically induced cranial nerve palsies developed in 38% of the patients. In 54% of cases it was possible to retain middle ear function. Seven patients had incomplete tumor removal requiring postoperative irradiation, with tumor progression occurring in 2 patients. Radical tumor removal was modified by efforts to reduce mutilating resections. These results show that individually tailored and combined multidirectional surgical approaches can allow total tumor removal to be performed with lower morbidity.

Adult↗
PubMed1997

Prognostic Factors Including Proliferation Markers Ki-67, bax, and bcl-2 in Temporal Bone Paraganglioma.

Valuable criteria with which to predict the clinical behavior of the temporal bone paraganglioma or the response to treatment are lacking. The analysis of markers of cell proliferation is a possibility to estimate the prognosis. Extensive patient data on 40 temporal bone paragangliomas were gathered over the years and correlated with the data obtained by staining histologic sections with bcl-2, bax, and MIB I markers of cellular proliferation. The immunohistochemistry was in all cases negative for bcl-2, positive for bax, and for Ki-67 positive in 20% of tumors. The scores for Ki-67 did not correlate with the majority of clinical parameters, except for treatment modality, preoperative hearing loss, and cranial nerve involvement. The tendency toward poorer hearing and a higher incidence of preoperative lower cranial nerve palsies was demonstrated in patients with higher Ki-67 scores. Furthermore, the higher rate of subtotal tumor removals in these patients reveals technical difficulties in accomplishing a radical removal, although the incidence of residual tumors was thus not affected. In view of the present information obtained with proliferation markers, the site of tumor origin still remains the most predictive variable for the course of the disease.

Journal Article↗
PubMed1997

Experimental sensorineural hearing loss following drill-induced ossicular chain injury.

In a guinea pig model, a standardized drill-induced injury to the body of the incus was applied, and the effects on hearing were characterized by electrocochleography. Drilling resulted in a threshold shift within seconds, and after 15 min it averaged 35.7 dB for clicks, 35 dB nHL for 4 kHz bursts, 36.7 dB nHL for 6 kHz bursts and 39 dB nHL for 8 kHz bursts. The deterioration of the threshold shift remained stable throughout the 5-week post-operative observation period. In five animals a disarticulation of the incudostapedial joint was performed prior to drilling, but this did not reduce the threshold shift. Caution is mandatory during drilling around an intact ossicular chain to avoid a permanent sensorineural hearing loss, and disarticulation of the incudostapedial joint prior to drilling has no protective value.

Animals↗
PubMed1996

[Juvenile xanthogranuloma of the auricle].

BACKGROUND: Juvenile xanthogranulomas are rare benign tumors of histiocytic origin with cutaneous manifestation predominantly in the head and neck. A case of a 12-month-old girl is presented. CASE REPORT: A tumor of the inferior crus of the left auricle had been noticed three weeks after birth. It was of yellowish color, bosselated and firm, and not mobile. During operation the tumor seemed lipomatoid and affected both cutis and subcutis. Histologically cutaneous structures were regular. Subcutaneously, cell-rich connective tissue with foamy histiocytes and Touton giant cells were observed as characteristic features of a juvenile xanthogranuloma. DISCUSSION: The pathogenesis of this tumor is unclear. The definite diagnosis is established by histological examination. Histological differentiation should include malignant tumors of histiocytic origin (dermatofibro-sarcoma protuberans, histiocytoma, atypical fibrous histiocytoma, fibro-xanthosarcoma) and malignant melanoma. Surgery is the treatment of choice only in cases in which the clinical diagnosis is doubtful, since juvenile xanthogranulomas usually heal spontaneously.

Diagnosis, Differential↗
PubMed1996

Long-term results of surgery for temporal bone paraganglioma.

The only way to resolve the dispute about the effectiveness of surgery versus radiation therapy for glomus tympanicum and jugulare tumors is adequate long-term studies. In a retrospective study with an average follow-up period of 15 years (range 11 to 23 years) we reassessed 11 patients with glomus tympanicum tumors and 11 patients with glomus jugulare tumors. Ten of 11 patients with glomus tympanicum tumor were tumor-free after surgery. A temporary facial palsy and an external meatal wall defect were the only surgical complications. The air-bone gap postoperatively closed to within 10 dB in three patients, to within 20 dB in six patients, and to more than 30 dB in one patient. Nine of 10 patients with glomus jugulare tumor receiving complete resection were tumor-free. Less than half the patients experienced new-onset cranial nerve function loss, and all made satisfactory recovery, eliminating the need for tracheostomy or gastrostomy. In two patients, the hearing could be preserved on the preoperative level, but the majority already presented with deafness. In the long-term, surgery remains a treatment of choice for glomus tympanicum tumors. It is also an extremely effective treatment with low morbidity for glomus jugulare tumors, including those with intracranial extension.

Journal Article↗
PubMed1996

Cyclic nucleotide-gated channels in identified human olfactory receptor neurons.

Patch-clamp recordings revealed the presence of a non-desensitizing cyclic nucleotide-gated channel on human olfactory receptor neurons and a fast-desensitizing non-specific cation channel activated by nucleotides on human supporting cells. Cyclic nucleotide-gated channels on olfactory receptor neurons showed selective channel activation by cAMP (K1/2 = 5 microM) and cGMP (K1/2 = 2 microM), a unitary conductance of approximately 20 pS, a reversal potential of single-channel currents close to 0 mV, a linear current-voltage relationship over the range of -80 to 80 mV and a strong extracellular but a weaker intracellular blocking effect of Ca2+. The channel activity outlasted the cyclic nucleotide pulses for hundreds of milliseconds when higher agonist concentrations (> 50 microM cAMP) were applied. The duration of the response was longer than in cyclic nucleotide-gated channels from other species studied so far. The plateau duration and the decay remained constant for pulses with a length of 50-150 ms, whereas pulses shorter than 50 ms successively reduced the time required by shortening the plateau phase. A larger difference for the K1/2 values of cAMP (K1/2 = 22 microM) and cGMP (K1/2 = 2.5 microM) were found for a small group (n = 3) of cyclic nucleotide-gated channels, pointing to the selective expression of the alpha-subunit in a small subgroup of olfactory receptor neurons.

Biomarkers↗
PubMed1996

Endonasal endoscopic closure of cerebrospinal fluid fistulas at the anterior cranial base.

This study reports our indications and limits for endonasal endoscopic closure of dural defects with a cerebrospinal fluid (CSF) leak at the anterior cranial base, and demonstrates our surgical technique. Fifty-three patients with CSF rhinorrhea were reassessed for the success rate of closure of the CSF leak. Surgery was successful in 98%, and 68% of fistulas were closed endoscopically. A free graft of autogenous mucoperiosteum of the inferior turbinate was the most frequently used tissue for defect closure. The endonasal endoscopic route proved relatively safe for the closure of dural tears, irrespective of the cause, up to about 10 x 10 mm. It is characterized by minimal morbidity because of the preservation of sinus ventilation and bony structures, supraorbital nerves, and olfactory fibers. Defects larger in size, predominantly of traumatic origin, were closed via the transfacial approach. The decision on the surgical approach was additionally based on the extent of the facial soft tissue injuries and the localization of the leak.

Cerebrospinal Fluid Rhinorrhea↗