A self-adjusting head holder without ear-bars for guinea pigs

Abstract

A self-adjusting head holder is designed to allow stable fixation and precise positioning (anterior-posterior, pitch, and roll) of guinea pig head in stereotaxic devices. These are achieved with no use of ear-bars. It is thus easy to use, preferable for studies of the auditory system, and for avoiding tissue damage of the ear in general. This head holder can accommodate various head sizes and is thus adapted for males and females of a large range of body weights, as confirmed for guinea pigs of 360-940 g. Moreover, this head holder is easy and cost-effective to manufacture, making it accessible for any lab. Here, we present background and mechanical rationale, the technical specifications, and step-by-step manufacturing instructions for the stainless-steel and the plastic MRI-compatible versions of our self-adjusting head holder.

A Novel 3D-Printed Head Holder for Guinea Pig Ear Surgery

“…The current design overcomes limitations of many commercially available stereotaxic head holders for small animal surgery by permitting simultaneous access of the ear and the snout. Other head holder designs rely on fixation using the hard palate, incisors, masticators, or the back of the nose, which all block the nose and mouth from receiving inhaled anesthesia via nose cone (1–5). Fried et al used a U-shaped head holder design with 4 pairs of bolts applied to side of mouse skull, without ear bars or nose clamp, to allow for rostral and unimpeded ear access; however, their design used a mouth bar preventing simultaneous nose cone anesthesia (1).…”

“…Guinea pigs and other small laboratory animals often require immobilization and precise positioning of the head during otologic and neurological surgeries while under anesthesia. Existing commercial head holders typically secure the head through the use of ear bars, nose clamps, or mouthpieces (1)(2)(3)(4)(5). Ear bars prevent surgical access to the external acoustic meatus, thereby preventing audiological testing and surgical access to the ear.…”

“…Ear bars prevent surgical access to the external acoustic meatus, thereby preventing audiological testing and surgical access to the ear. Nose clamps and mouthpieces are affixed to the nasal cavity and the hard palate and teeth respectively, which impede the use of nose cone anesthesia (2)(3)(4)(5). Furthermore, these commercial frames are expensive and cumbersome within most experimental setups.…”