As you're already aware, I cannot offer a diagnosis in a forum such as this.
That said, I would be hesitant to characterize your husband's behavior as symptomatic of Intermittent Explosive Disorder. This condition is characterized, from the DSM-IV, by "several discrete episodes of failure to resist aggressive impulses that result in serious assaultive acts or destruction of property" and "the degree of aggressiveness expressed during the episodes is grossly out of proportion to any precipitating psychosocial stressors." I don't see evidence, in your report, of several similar episodes which would negate this as a diagnosis. Also, the behavior must result in serious physical injury or major property damage. Again, that didn't happen in this case. It was certainly a frightening and shocking display of rage, but does not rise to the level required by this diagnosis. Intermittent Explosive Disorder had in the past been considered to be the result of a neurological disorder, but is now widely treated with serotonergic medications such as Prozac.
I would be much more inclined to look into the bipolar
disorders, given that you report he has mood swings. An individual in a manic or hypomanic state can display this sort of aggressive behavior. Yet, even that diagnosis may be too strong for him.
First, your husband needs to be evaluated by another medical professional. What strikes me is that this behavior has not been, per your report, a consistent pattern, but a rather sporadic one. I'm wondering if it is not influenced by an underlying medical condition.
Second, I would have him visit a psychiatrist for a complete evaluation. I suspect that whatever his diagnosis, it may be best treated with medication.
Third, if he is in therapy, I would encourage his therapist to work with your husband on anger management skills training, cognitive restructuring, and improving coping skills. These would best be provided by a qualified cognitive-behavioral therapist in your area.
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