No abstract

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With the use of this technique, the surgeon can precisely identify the position of the surgical instrument without losing his or her way, thereby significantly reducing the rate of complications.

In a previous investigation the relationship between head size and main parameters of ABR, i.e. waves absolute latencies and interwave delays, was studied in 55 subjects (1). Significant and positive correlation coefficients were found between I-V I.P.I. and the sum of head circumference, nasion-inion, and intertragal distances in the age range 7 to 11 years only and not in adult age. The purpose of the present study was to verify whether in 11 adults a correlation could be demonstrated between ABR parameters and two axial measures of brainstem length, calculated on MRI views. A positive and significant coefficient was found to exist between these measures and I-V I.P.I. and wave V absolute latency.

The findings of the present study can be summed up in the following points: (1) brainstem auditory evoked potentials (BAEP), as compared with magnetic resonance imaging (MRI), has a greater capacity and a lower cost in disclosing brainstem plaques both in MS patients with symptoms or signs of actual brainstem involvement and in clinically silent ones. This makes BAEP a useful technique for the neurologist, who can confirm the clinical suspicion of a brainstem lesion and follow the evolution of the disease in the patient. (2) The sensitivity of BAEP is lower than that of MRI as far as the anterior lesions of the brainstem are concerned. (3) MRI is more specific than BAEP, inasmuch as several types of injuries can alter the BAEP, while the demyelinating plaque has a specific image and can only be confused with little lacunar infarcts. (4) Plaques that produced symptoms or signs in the past can eventually disappear and be no longer detected by a subsequent MRI.