Richard Chavez (Worker) was injured on April 13,1989, when the truck he was driving rolled over. As a result of the accident, Worker sustained a laceration to his head and a torn rotator cuff. The injury to his rotator cuff left Worker with a permanent physical impairment of thirty percent of the right upper extremity at or above the shoulder. Based on this physical impairment, the Workers’ Compensation Judge (WCJ) determined that Worker was forty-eight percent permanently partially disabled. The WCJ also found that Worker suffered from a psychological condition known as Ganser’s Syndrome. The WCJ found the mental condition causally related to the same motor vehicle accident that caused the shoulder injury, but not within the statutory definitions of either primary or secondary mental impairment, contained in NMSA 1978, Sections 52-1-24(B) and (C) (Repl.Pamp.1991). Based on the plain meaning of the statutory language, we affirm.
I. STATUTORY REQUIREMENTS FOR MENTAL IMPAIRMENT
Under the 1987 version of the Workers’ Compensation Act, NMSA 1978, Sections 52-1-1 to -70 (Repl.Pamp.1987), recovery for mental impairment was governed by Section 52-1-24.1 Subsection B of that statute defined primary mental impairment in the following terms:
B. “primary mental impairment” means a mental illness arising from an accidental injury arising out of and in the course of employment when the accidental injury involves no physical injury and consists of a psychologically traumatic event that is generally outside of a worker’s usual experience and would evoke significant symptoms of distress in a worker in similar circumstances, but is not an event in connection with disciplinary, corrective or job evaluation action or cessation of the worker’s employment.
Secondary mental impairment was defined by Section 52-l-24(C), which provided:
*794C. “secondary mental impairment” means a mental illness resulting from a physical impairment caused by an accidental injury arising out of and in the course of employment.
II. THE DECISION OF THE WCJ
The WCJ took the somewhat unusual step of filing a memorandum opinion in this case. As we find the factual basis of the WCJ’s opinion significant and the logic compelling, we quote from it liberally. The WCJ set forth the factual foundation of his decision as follows:
Ganser’s Syndrome is a psychological condition by which a person behaves as if there were severe cognitive malfunctions. Ganser’s Syndrome is a psychological condition, and is not related to a physical malady such as dementia or organic brain injury.
In this case it is my determination, based on the evidence presented at trial, that Worker suffers from Ganser’s Syndrome. Worker is rendered totally disabled by reason of Ganser’s Syndrome. The Ganser’s Syndrome is causally related to the work accident of April 13, 1989. In that same accident Worker suffered a laceration to his head, and a torn rotator cuff to his right shoulder.
In this case Worker suffered a head laceration which fully resolved. In addition, Worker suffered a torn rotator cuff to his right shoulder which has left him with a 30% permanent physical impairment to the right upper extremity as determined by his physicians. Worker has been rendered partially disabled by reason of this shoulder injury.
The WCJ also considered the statutory definitions of primary and secondary impairment, as well as their application to a psychological disability caused by the accident but unrelated to any physical injuries resulting from the accident:
The Workers’ Compensation Act defines primary mental impairment as a mental illness arising from an accidental injury arising out of and in the course of employment, where there is no physical injury and the accident consists of a psychologically traumatic event that would evoke significant symptoms of distress in a Worker in similar circumstances. Secondary mental impairment is defined as a mental illness resulting from a physical impairment caused by an accidental injury arising out of and in the course of employment. The Ganser’s Syndrome in this case did not derive from a psychologically traumatic event outside of the Worker’s usual experience. Nor, can it properly claimed [sic] that the accident would evoke significant symptoms of distress in a Worker in similar circumstances. The Ganser’s Syndrome does not derive from a physical impairment caused by an accidental injury, but is rather directly related to the accident of April 13,1989. It can therefore be seen that Ganser’s Syndrome fits neither the definition of primary mental impairment, nor the definition of secondary mental impairment so as to render it a compensable condition under the New Mexico Workers’ Compensation Act. While Worker is disabled as a result of the Ganser’s Syndrome, the fact that the condition is non-eompensable means that the Worker cannot receive compensation as a result of that condition.
The WCJ made several findings of fact relevant to his decision on mental impairment:
16. As a direct and proximate result of the accident of April 13, 1989, to a reasonable medical probability, Worker suffered an injury to the head and right shoulder. The nature of the injury is laceration of the head and torn rotator cuff of the right shoulder. Worker also suffers from Ganser’s Syndrome.
17. Ganser’s Syndrome is causally related to the April 13, 1989 accident, but is not a primary mental impairment within the Act, nor is it secondary to a physical injury.
*79530. Worker’s disability from Ganser’s Syndrome is causally related to the accident of April 13, 1989.
31. Worker is unable to return to his former job.
32. Worker would not likely benefit from vocational rehabilitation. This is because of the Ganser’s Syndrome.
At least one of the WCJ’s conclusions of law also relates to the nature of the disability caused by the Ganser’s Syndrome:
16. Worker is not entitled to weekly benefits based on Ganser’s Syndrome, as that condition fits neither primary, nor secondary impairment definitions so as to render it compensable.
Under Section 52-l-24(B), a worker can' recover for primary mental impairment only “when the accidental injury involves no physical injury.” The present ease clearly involved a physical injury, for which compensation benefits were awarded. Worker’s injury therefore does not fall within the definition of primary mental impairment. Moreover, the WCJ expressly recognized that the accidental injury “in this case did not derive from a psychologically traumatic event outside of the Worker’s usual experience.” There is also no evidence in the record to show that Worker was predisposed to such a psychological disorder or that such an accident “would evoke significant symptoms of distress in a worker in similar circumstances.” Section 52-l-24(B). These factors provide a second basis for the WCJ’s conclusion that Worker’s Ganser’s Syndrome is not within the statutory definition of a primary mental impairment.
In order to recover for a secondary mental impairment the mental illness must be the result of a physical impairment. We agree with Worker that it was not necessary for him to prove the Ganser’s Syndrome was caused by a physical injury to the brain. Under the clear language of Section 52-1-24(C), however, Worker was required to prove that the Ganser’s Syndrome resulted from a physical impairment of some nature. After reviewing the evidence, the WCJ concluded, “[t]he Ganser’s Syndrome does not derive from a physical impairment caused by an accidental injury, but is rather directly related to the accident of April 13, 1989.” Worker does not argue that there is not substantial evidence to support the WCJ’s decision but rather that there was evidence from which the WCJ could have concluded that the Ganser’s Syndrome was the result of a physical impairment caused by the accident. However, the fact that there is other evidence upon which a lower court could have reached a different conclusion does not make its decision erroneous. Jay Walton Enters, v. Rio Grande Oil Co., 106 N.M. 55, 60, 738 P.2d 927, 932 (Ct.App.), cert. denied, 106 N.M. 7, 738 P.2d 125 (1987). Here, there is substantial evidence that Worker’s injury was not the result of a physical impairment and thus is not within the definition of a secondary mental impairment under Section 52-l-24(C).
“The chief aim of statutory construction is to give effect to the intent of the legislature.” Roth v. Thompson, 113 N.M. 331, 332, 825 P.2d 1241, 1242 (1992). This standard “ordinarily requires [the court] to determine the legislative intent primarily from the language used in the statute as a whole. When the words of the statute are free from ambiguity and doubt, resort should not be undertaken to any other means of interpretation.” State ex rel. Stratton v. Roswell Indep. Sch., 111 N.M. 495, 500, 806 P.2d 1085, 1090 (Ct.App.1991) (citation omitted). “Section 52-1-24 restricts the rights to recover for work-related ‘mental impairment’ to those types of impairment expressly specified in the statute.” Douglass v. State, Regulation & Licensing Dep’t, 112 N.M. 183, 186, 812 P.2d 1331, 1334 (Ct.App.), cert. denied, 112 N.M. 77, 811 P.2d 575 (1991). In the present case the definitions of mental impairment are clear, so we do not look to *796any other source to determine legislative intent.2
The decision of the WCJ is affirmed.
IT IS SO ORDERED.
FLORES, J., concurs.
DONNELLY, J., files dissenting opinion.