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100 Section II: Intracranial Procedures

Despite the multiple tasks of the frontal lobe, “silent” areas Transfrontal craniotomy is limited by the anatomy of the area,
have been identified experimentally in the frontal lobes of ani­ extent of the tumor, and exposure provided by the surgical
mals. “Silent” areas of the cerebral cortex can be stimulated approach: a good exposure provided by an adequate surgical
mechanically, chemically, or electrically without producing an approach is important for the success of the technique and avoids
obvious motor or sensory response. Lesions produced experimen­ postsurgical complications. Transfrontal craniotomy in veterinary
tally in frontal lobe areas are reported to cause no signs, seizures, medicine was described in dogs in 1972 by Parker and
or behavior changes such as uncontrolled rage or apathy [8]. Cunningham [11], by DeWet et al. in 1982 [12], and by Kostolich
Generalized seizures commonly precede abnormalities in the and Dulisch in 1987 [10]. These approaches combined a rostro‐
neurological examination when the lesion is localized on the fron­ tentorial approach with a transfrontal approach and proximal
tal lobe. Slow‐growing or small tumors have traditionally been transfrontal sinus approach with destruction of the cribriform
regarded as the cause of this observation, although prefrontal plate. Clear visualization with adequate exposure was limited by
location has been proposed to result in seizures without neuro­ these surgical approaches. Moreover, severe postoperative com­
logical deficits in dogs [9]. Consequently, the absence of neuro­ plications were recorded [10]. In 2000, Glass et al. [13] proposed a
logical deficits on initial examination appears to be an unlikely modified bilateral transfrontal sinus approach in five dogs, and in
predictor of space‐occupying masses in the rostral cerebrum. 2011 Uriarte et al. [14] described a bilateral and unilateral trans­
Therefore, it is not uncommon for the neurosurgeon to encounter frontal sinus approach in seven dogs with frontal meningiomas.
large tumors in this area. Transfrontal craniotomies in dogs have Both papers demonstrated a satisfactory exposure of the frontal
been related to severe postsurgical complications such as general lobe without major postsurgical complications.
seizures and postoperative surgical infection in the first described
frontal craniotomies [10–12].

Indications
Sagittal crest
Interparietal process Transfrontal craniotomies/craniectomies are indicated for exposure
Parietal bone Frontal bone of the dorsal frontal cortices (approximately the cruciate sulci),
olfactory bulbs, and ethmoidal areas. The types of lesions with indi­
cations for surgery include neoplastic, vascular (primary or second­
Frontal sinus
ary hemorrhages), head trauma (depression fracture), infectious
Cribriform plate (abscesses or granulomas), and congenital abnormalities.
Occipital bone Temporal fossae
Neoplastic
Maxilla
The most common surgically approachable pathology found in the
canine frontal lobe is a neoplastic lesion. In a review of tumors
Zygomatic
affecting the rostral cerebrum, meningioma was the most common
tumor type (30%), followed by astrocytoma (16%), nasal neuroen­
Frontal fossae docrine carcinoma (14%), and neuroblastoma (12%) [8]. Excision
of frontal meningiomas by transfrontal craniotomy has been
described successfully in a case series by Glass et al. [13] and by
Uriarte et al. [14]. Bilateral or unilateral transfrontal approaches
Figure 10.3 View from a partially opened skull showing the principal bony allow easy access to tumors located on the olfactory lobe and dorsal
structures. frontal lobe (Figures 10.5 and 10.6).

Figure 10.4 Three skulls from brachycephalic, mesocephalic, and dolichocephalic dogs with their related frontal sinuses.